Method and communication device for determining separation between user plane network elements

Abstract

In order to determine whether the user plane network elements are separated in a control and user plane separation scenario, a method and a communication device for determining separation between user plane network elements are provided. The method can be implemented by using the following steps: a first control plane network element obtains a first node identifier of the first user plane network element and a second node identifier of the second user plane network element, the first control plane network element includes a serving gateway for the control plane, a data network gateway for the control plane, a session management function, or an intermediate session management function, and the first user plane network element is a user plane anchor. The first control plane network element determines whether the first user plane network element is separated from the second user plane network element based on the first node identifier and the second node identifier.

Description

[Technical field]

[0001] TECHNICAL FIELD Embodiments of the present application relate to the field of communication technologies, and in particular to a method and a communication device for determining isolation between user plane network elements. [Background technology]

[0002] The user plane and the control plane can be deployed centrally or separately. In a control and user plane separation scenario, for example, most of the control plane network elements are deployed centrally in state capitals or regional centers, and the user plane network elements are deployed in cities close to the users. In this deployment scenario, a moving terminal device is likely to cross the areas managed by the user plane service network elements. However, during the movement of the terminal device, the user plane network elements are usually anchored and do not change. For example, in an evolved packet core (EPC) scenario or when a 5th generation (5G) terminal device activates a session and service continuity (SSC) mode 1 (Mode 1) protocol data unit (PDU) session, in the 3rd generation partnership project (3GPP) protocol, the user plane network providing data services to the terminal device must be anchored and unchanged during the movement of the terminal device. In this case, the two user plane network elements may be separated, resulting in traffic diversion.

[0003] In view of this, it needs to be determined whether the user plane network element is separated in the control and user plane split scenario, and further measures need to be taken to avoid traffic diversion. Therefore, how to determine whether the user plane network element is separated in the control and user plane split scenario is a problem to be solved. Summary of the Invention

[0004] The embodiments of the present application provide a method and a communication device for determining separation between user plane network elements, to determine whether the user plane network elements are separated in a control and user plane separation scenario.

[0005] According to a first aspect, a method for determining separation between user plane network elements is provided. The method may be applied to a control and user plane separation scenario, or the method may be applied to a control and user plane separation communication system. The method may be executed by a first control plane network element, or may be executed by a component of the first control plane network element. For example, the method is executed by the first control plane network element. The method may be implemented by using the following steps: the first control plane network element obtains a first node identifier of the first user plane network element and a second node identifier of the second user plane network element, and the first control plane network element includes a serving gateway SGW-C for control plane (which may be denoted as first SGW-C), a data network PDN gateway PGW-C for control plane (which may be denoted as first PGW-C), a session management function network element SMF, or an intermediate session management function network element I-SMF. The first user plane network element is a user plane anchor. The first control plane network element determines whether the first user plane network element is isolated from the second user plane network element based on the first node identifier and the second node identifier. The first control plane network element compares the node identifiers of the two user plane network elements to determine whether the user plane network elements are isolated, so that whether the user plane gateways are isolated can be determined in a control and user plane isolation scenario, and the efficiency and accuracy of determining isolation between the user plane gateways can be improved, so that measures can be taken in a timely manner when the user plane gateways are isolated to avoid traffic diversion.

[0006] The following description is based on a kind of first control plane network element.

[0007] When the first control plane network element is a first SGW-C or a first PGW-C, the following possible designs may be provided.

[0008] According to the first aspect, the method may be implemented by using the following steps: a first control plane network element obtains a node identifier of a first PGW-U and a node identifier of a first SGW-U. The first control plane network element determines whether a user plane gateway is separated based on the node identifier of the first PGW-U and the node identifier of the first SGW-U, and the user plane gateway determines whether a user plane gateway is separated based on the node identifier of the first PGW-U and the node identifier of the first SGW-U. No. 1 The first control plane network element includes an SGW-U and a PGW-U, which are denoted as PGW-U. That is, the first control plane network element determines whether the first SGW-U is detached from the first PGW-U based on the node identifier of the first PGW-U and the node identifier of the first SGW-U. The first PGW-U is a user plane anchor for a terminal device to access the PDN. The first control plane network element may be a first SGW-C or a first PGW-C. The first control plane network element determines whether the first SGW-U is detached from the first PGW-U based on the node identifier of the first PGW-U and the node identifier of the first SGW-U, so that whether the user plane network element is detached can be determined in a CUPS scenario, and the efficiency and accuracy of determining the detachment between the user plane network elements can be improved, so that measures can be taken timely when the user plane network element is detached to avoid traffic diversion.

[0009] In a possible design, the first control plane network element is an SGW-C. The first control plane network element may obtain a node identifier of the first PGW-U in the following manner: the SGW-C obtains the node identifier of the first PGW-U from the PGW-C, and the PGW-C is a control plane anchor for the terminal device to access the PDN.

[0010] When the SGW-C and the PGW-C are located in the same control plane gateway node, the SGW-C can obtain the node identifier of the first PGW-U from the local PGW-C, i.e., obtain the node identifier of the first PGW-U by using an internal message, which can reduce signaling overhead and does not require changes to the signaling of existing protocols.

[0011] When the SGW-C and the PGW-C are located in different control plane gateway nodes, the PGW-C can obtain the node identifier of the first PGW-U by exchanging messages with the SGW-C. For example, the SGW-C receives a Modify Bearer Response message from the PGW-C, and the Modify Bearer Response message carries the node identifier of the first PGW-U. In this way, the node identifier can be carried in existing signaling to determine the separation between the user plane network elements.

[0012] In a possible design, the first control plane network element is a PGW-C, which is a control plane anchor for a terminal device to access the PDN. The first control plane network element may obtain a node identifier of the first SGW-U in the following manner: The PGW-C obtains a node identifier of the first SGW-U from the SGW-C.

[0013] When the SGW-C and the PGW-C are located in the same control plane gateway node, the PGW-C can obtain the node identifier of the first SGW-U from the local SGW-C, that is, the PGW-C can obtain the node identifier of the first SGW-U by using an internal message, which can reduce signaling overhead and does not require changes to the signaling of existing protocols.

[0014] When the SGW-C and the PGW-C are located in different control plane gateway nodes, the SGW-C performs the first SGWFor example, the PGW-C receives a Modify Bearer Request message from the SGW-C, and the Modify Bearer Request message carries the node identifier of the first SGW-U. In this way, the node identifier can be carried in existing signaling to determine the separation between user plane network elements.

[0015] In the following design of the determination method for determining whether the first SGW-U is detached from the first PGW-U, the node identifier of the first SGW-U and the node identifier of the first PGW-U may be expressed by using a first node identifier and a second node identifier, respectively.

[0016] In a possible design, the first control plane network element determining whether the first SGW-U is disassociated from the first PGW-U based on the first node identifier and the second node identifier may include the following method: if the first node identifier is the same as the second node identifier, determine that the first SGW-U is not disassociated from the first PGW-U, or if the first node identifier is different from the second node identifier, determine that the first SGW-U is disassociated from the first PGW-U. This determination method is strict and accurate. Using the determination method to determine disassociation between user plane network elements may help to improve the determination accuracy. Furthermore, in this determination method, the node identifiers do not need to be named in a structured manner. If the node identifier is currently set in the on-net device, the on-net device does not need to change the node identifier.

[0017] In a possible design, the first control plane network element determining whether the first SGW-U is detached from the first PGW-U based on the first node identifier and the second node identifier may further include the following method: if the first information in the first node identifier is the same as the second information in the second node identifier, determine that the first SGW-U is not detached from the first PGW-U; or if the first information in the first node identifier is different from the second information in the second node identifier, determine that the first SGW-U is detached from the first PGW-U, where the first information indicates the area where the first SGW-U is located and the second information indicates the area where the first PGW-U is located. When the two user plane network elements are not in the same node but in the same area, the path transmission redundancy is not so large and the requirement of PDN re-establishment is not so high. In this determination method, whether the user plane network element is detached can be flexibly determined. Compared with the method of determining that a user plane network element is separated across user plane network elements, in this determination method, the user plane network element is determined to be separated only when an area spans between the user plane network elements, and an operation, for example, PDN re-establishment, is further performed after separation, thereby avoiding signaling consumption caused by unnecessary PDN re-establishment.

[0018] In a possible design, the first control plane network element determining whether the first SGW-U is detached from the first PGW-U based on the first node identifier and the second node identifier may further include the following method: if the first node identifier and the second node identifier are in the same group, determine that the first SGW-U is not detached from the first PGW-U; or if the first node identifier and the second node identifier are not in the same group, determine that the first SGW-U is detached from the first PGW-U, and the SGW-U and PGW-U in the group are located in the same area. When the two user plane network elements are not in the same node but in the same area, the path transmission redundancy is not so large and the requirement of PDN re-establishment is not so high. In this determination method, whether the user plane network element is detached can be flexibly determined. Compared with the method of determining that a user plane network element is separated across user plane network elements, in this determination method, the user plane network element is determined to be separated only when an area spans between the user plane network elements, and an operation, for example, PDN re-establishment, is further performed after the separation. This can avoid signaling consumption caused by unnecessary PDN re-establishment. Furthermore, in this determination method, the node identifier does not need to be named in a structured manner. If the node identifier is currently configured in the on-net device, the on-net device does not need to change the node identifier.

[0019] In a possible design, when the first control plane network element determines that the first SGW-U has separated from the first PGW-U, the first control plane network element initiates re-establishment of a PDN connection to the terminal device.

[0020] Based on when the first control plane network element determines that the first SGW-U is disassociated from the first PGW-U, the first control plane network element initiates re-establishment of a PDN connection to the terminal device. Optionally, if the first control plane network element is an SGW-C, the SGW-C may initiate re-establishment of a PDN connection to the terminal device when the S1 connection to the terminal device is released. Furthermore, optionally, the SGW-C may start a timer when the S1 connection to the terminal device is released, and initiate re-establishment of a PDN connection to the terminal device after the timer has elapsed. It should be noted that the SGW-C may initiate re-establishment of some or all of the PDN connections to the terminal device. Since the timer is started when the S1 connection to the terminal device is released, impact on ongoing data and voice services can be avoided.

[0021] Based on when the first control plane network element determines that the first SGW-U is disassociated from the first PGW-U, the first control plane network element initiates re-establishment of a PDN connection to the terminal device. Optionally, when the first control plane network element is a PGW-C, the PGW-C may initiate re-establishment of a PDN connection to the terminal device when the terminal device has no traffic within a specified time. In this way, impact on ongoing data and voice services can be avoided.

[0022] In a possible design, when initiating re-establishment of a PDN connection to the terminal device, the first control plane network element may send a delete bearer request to the MME, where the delete bearer request carries information about a deletion cause, and the information about the deletion cause indicates that reactivation is requested. The terminal device can be reactivated by carrying the information about the deletion cause. In the activation process, the first control plane network element selects a combined SGW-U / PGW-U for the terminal device, so that the user plane network elements can be combined and the path for forwarding data or voice traffic is better.

[0023] When the first control plane network element is an SMF or an I-SMF, the following possible designs may be provided.

[0024] According to the first aspect, the method may be implemented by using the following steps: a first control plane network element obtains a node identifier of a first PSA-UPF and a node identifier of a first I-UPF. The first control plane network element determines whether a user plane network element is disjoint based on the node identifier of the first I-UPF and the node identifier of the first PSA-UPF, the user plane network element including an I-UPF and a PSA-UPF, denoted as the first I-UPF and the first PSA-UPF. That is, the first control plane network element determines whether the first I-UPF is disjoint from the first PSA-UPF based on the node identifier of the I-UPF and the node identifier of the PSA-UPF. The first PSA-UPF is a user plane anchor for the terminal device.

[0025] In a possible design, the first control plane network element is an I-SMF. The first control plane network element may obtain a node identifier of the first PSA-UPF in the following manner: The I-SMF obtains the node identifier of the first PSA-UPF from the SMF.

[0026] When the I-SMF is inserted, the I-SMF may obtain a node identifier of the first PSA-UPF by exchanging messages with the SMF. Optionally, the SMF may send a PDU Session Create Response (Nsmf_PDUSession_Create Response) message to the I-SMF, where the PDU Session Create Response message carries the node identifier of the first PSA-UPF. The I-SMF receives the PDU Session Create Response message from the SMF, where the I-SMF obtains the node identifier of the first PSA-UPF from the PDU Session Create Response message. In this way, the node identifier can be carried in existing signaling to determine separation between user plane network elements.

[0027] In a possible design, the first control plane network element is an SMF. The first control plane network element may obtain a node identifier of the first I-UPF in the following manner.

[0028] When the I-SMF is inserted, the SMF may obtain a node identifier of the first I-UPF by exchanging messages with the I-SMF. Optionally, the I-SMF may send a PDU Session Create Request (Nsmf_PDUSession_Create Request) message to the SMF, and the PDU Session Create Request message may carry the node identifier of the first I-UPF. The SMF receives the PDU Session Create Request message from the I-SMF and obtains the node identifier of the first I-UPF from the PDU Session Create Request message. In this way, the node identifier can be carried in existing signaling to determine the separation between user plane network elements.

[0029] In the following design of the decision method for determining whether the first I-UPF is separated from the first PSA-UPF, the node identifier of the first I-UPF and the node identifier of the first PSA-UPF may be represented by a first node identifier and a second node identifier, respectively.

[0030] In a possible design, the first control plane network element determining whether the first I-UPF is disjoint from the first PSA-UPF based on the first node identifier and the second node identifier may include the following method: if the first node identifier is the same as the second node identifier, determine that the first I-UPF is not disjoint from the first PSA-UPF, or if the first node identifier is different from the second node identifier, determine that the first I-UPF is disjoint from the first PSA-UPF. This determination method is rigorous and accurate. Using the determination method to determine disjoint between user plane network elements may help improve the determination accuracy.

[0031] In a possible design, the first control plane network element determining whether the first I-UPF is separated from the first PSA-UPF based on the first node identifier and the second node identifier may further include the following method: determining that the first I-UPF is not separated from the first PSA-UPF if the first information in the first node identifier is the same as the second information in the second node identifier, or determining that the first I-UPF is separated from the first PSA-UPF if the first information in the first node identifier is different from the second information in the second node identifier, the first information indicating the area in which the first I-UPF is located, and the second information indicating the area in which the first PSA-UPF is located. When the two user plane network elements are not in the same node but in the same area, the path transmission redundancy is not so large and the requirement of PDU session re-establishment is not so high. In this determining method, whether the user plane network elements are separated can be flexibly determined. Only when there is an area span between the user plane network elements, it is determined that the user plane network elements are separated, and an action, e.g., PDU session re-establishment, is further performed after the separation, thereby avoiding signaling consumption caused by unnecessary PDU session re-establishment.

[0032] In a possible design, the first control plane network element determining whether the first I-UPF is disjoint from the first PSA-UPF based on the first node identifier and the second node identifier may further include the following method: if the first node identifier and the second node identifier are in the same group, determine that the first I-UPF is not disjoint from the first PSA-UPF; or if the first node identifier and the second node identifier are not in the same group, determine that the first I-UPF is disjoint from the first PSA-UPF, and the I-UPF and PSA-UPF in the group are located in the same area. When the two user plane network elements are not in the same node but in the same area, the path transmission redundancy is not so large and the requirement of PDU session re-establishment is not so high. In this determination method, whether the user plane network elements are disjoint can be flexibly determined. Only when the areas span between the user plane network elements, it is determined that the user plane network elements are disjoint, and an operation, for example, PDU session re-establishment, is further performed after the disjoint. This avoids signaling consumption caused by unnecessary PDU session re-establishment.

[0033] In a possible design, when the first control plane network element determines that the first I-UPF has separated from the first PSA-UPF, the first control plane network element initiates re-establishment of a PDU session to the terminal device.

[0034] When the first control plane network element determines that the first I-UPF is separated from the first PSA-UPF, the first control plane network element PDU SessionsOptionally, if the first control plane network element is an I-SMF, the I-SMF may initiate re-establishment of a PDU session to the terminal device when the N1 / N2 connection to the terminal device is released. Furthermore, optionally, the I-SMF may start a timer when the N1 / N2 connection to the terminal device is released, and start re-establishment of the PDU session of the terminal device after the timer has elapsed. It should be noted that the I-SMF may initiate re-establishment of some or all of the PDU sessions to the terminal device. Since the timer is started when the N1 / N2 connection to the terminal device is released, any impact on ongoing data and voice services can be avoided.

[0035] When the first control plane network element determines that the first I-UPF is dissociated from the first PSA-UPF, the first control plane network element initiates re-establishment of a PDU session to the terminal device, and optionally, when the first control plane network element is an SMF, the SMF may initiate re-establishment of a PDU session of the terminal device when the PDU session / terminal device has no traffic within a specified time. In this way, impact on ongoing data and voice services can be avoided.

[0036] In a possible design, when initiating re-establishment of a PDU session of a terminal device, the first control plane network element may send a delete bearer request to the AMF, where the delete bearer request carries information about a deletion cause, and the information about the deletion cause indicates that reactivation is requested. The terminal device may be reactivated by carrying the information about the deletion cause. In the activation process, the first control plane network element selects a nearby PSA-UPF for the terminal device to avoid I-UPF insertion, so that a path for forwarding data or voice traffic is better.

[0037] According to a second aspect, a method for determining disassociation between user plane network elements is provided. The method may be performed by a serving gateway for control plane SGW-C, or may be performed by a component of the serving gateway for control plane SGW-C. For example, the method is performed by the serving gateway for control plane SGW-C. The method may be implemented by using the following steps: the SGW-C obtains an address of a first PGW-C; the SGW-C determines whether a serving gateway for user plane SGW-U is disassociated from the first PGW-U based on the address of the first PGW-C and a preset address, or the SGW-C determines whether a PDN connection of a terminal device should be re-established based on the address of the first PGW-C and the preset address, the preset address including an address of one or more PGW-C located in the same area as the SGW-C, the first PGW-U is a user plane anchor for the terminal device to access the PDN, and the first PGW-C is a control plane anchor for the terminal device to access the PDN. The SGW-C determines whether the user plane network element is separated based on the address of the control plane gateway, and determines that the user plane network element is separated when it determines that the control plane gateway is separated (i.e., the address of the first PGW-C is not in the preset address) by presetting the control plane gateway group based on the area. The preset address is the address of the PGW-C in the same area as the SGW-C. In this way, the area can be divided based on the service requirements, and the preset address is set so that the separation between the user plane network elements is more flexibly determined to satisfy the service requirements. Furthermore, since the gateway nodes do not need to be named in a normative and structured manner and the decision granularity is large, the decision result of the separation between the user planes can be reduced, and the actions taken after determining that the user plane is separated, such as PDN re-establishment, can be further reduced to reduce the signaling overhead.

[0038] In a possible design, the control plane serving gateway SGW-C and the first control plane data network PDN gateway PGW-C are located in different control plane gateway nodes. In general, when the SGW-C and the first PGW-C are located in different control plane gateway nodes, i.e., when the control plane gateways are separated, the user plane network elements are considered to be separated by default. In the solution of the second aspect, when the SGW-C and the first PGW-C are located in different control plane gateway nodes, whether the user plane network elements are separated needs to be further determined based on the address and the preset address of the first PGW-C. Based on the service requirements, the operator considers the SGW-U and the PGW-U to be separated only when a wide area range needs to be crossed between the SGW-U and the PGW-U. The solution of the second aspect is applicable to such service requirements of the operator.

[0039] In a possible design, the SGW-C may determine whether the serving gateway for user plane SGW-U has detached from the first PGW-U based on the address of the first PGW-C and the preset address in the following manner: if the preset address includes the address of the first PGW-C, the SGW-C determines that the SGW-U has not detached from the first PGW-U, or if the preset address does not include the address of the first PGW-C, the SGW-C determines that the SGW-U has detached from the first PGW-U.

[0040] In a possible design, when the SGW-C determines that the SGW-U has detached from the first PGW-U, the SGW-C initiates re-establishment of a PDN connection to the terminal device.

[0041] Based on when the SGW-C determines that the SGW-U is detached from the first PGW-U, the SGW-C initiates re-establishment of a PDN connection to the terminal device: optionally, the SGW-C initiates re-establishment of a PDN connection to the terminal device when the S1 connection to the terminal device is released. In this way, impact on ongoing data and voice services can be avoided. Furthermore, optionally, the SGW-C may start a timer when the S1 connection to the terminal device is released, and initiate re-establishment of a PDN connection to the terminal device after the timer has elapsed. Since the timer is started when the S1 connection to the terminal device is released, impact on ongoing data and voice services can be avoided.

[0042] In a possible design, when initiating re-establishment of a PDN connection to a terminal device, the SGW-C may send a delete bearer request to the MME, where the delete bearer request carries information about the delete cause, and the information about the delete cause indicates that reactivation is requested. The terminal device can be reactivated by carrying the information about the delete cause. In the activation process, the SGW-C selects a combined SGW-U / PGW-U for the terminal device, so that the user plane network elements can be combined and the path for forwarding data or voice traffic is better.

[0043] According to a third aspect, there is provided a method for determining disjoint between user plane network elements. The method may be executed by a first control plane network element, or may be executed by a component of the first control plane network element, and the first control plane network element may be a PGW-C. For example, the method is executed by the PGW-C. The method may be implemented by using the following steps: the PGW-C obtains an address of a first SGW-C. The PGW-C determines whether a PGW-U is disjoint from a first SGW-U based on the address of the first SGW-C and a preset address, the preset address including addresses of one or more SGW-C located in the same area as the PGW-C, the PGW-U being a user plane anchor for a terminal device to access a PDN, and the PGW-C being a control plane anchor for a terminal device to access a PDN. The PGW-C determines whether the user plane network element is separated based on the address of the control plane gateway, and determines that the user plane network element is separated when it determines that the control plane gateway is separated (i.e., the address of the first SGW-C is not in the preset address) by presetting the control plane gateway group based on the area. The preset address is the address of the SGW-C in the same area as the PGW-C. In this way, the area can be divided based on the service requirements, and the preset address is set so that the separation between the user plane network elements is more flexibly determined to satisfy the service requirements. Furthermore, since the gateway nodes do not need to be named in a normative and structured manner, and the granularity of the decision is large, the decision result of the separation between the user planes can be reduced, and the actions taken after the user plane is determined to be separated, such as PDN re-establishment, can be further reduced to reduce the signaling overhead.

[0044] In a possible design, the PGW-C and the first SGW-C are located in different control plane gateway nodes. PGW-C and 1 SGW - When C is located in a different control plane gateway node, i.e., when the control plane gateways are separate, the user plane network elements are considered to be separate by default. PGW -C and 1 SGW -When C are located in different control plane gateway nodes, whether the user plane network elements are separated is further determined by the first SGW The address of the SGW-U and the PGW-U must be determined based on the address of the SGW-U and the preset address. Based on the service requirements, the operator considers the SGW-U and the PGW-U to be separate only when a wide area range needs to be crossed between the SGW-U and the PGW-U. The solution in the third aspect is applicable to such service requirements of the operator.

[0045] In a possible design, the PGW-C may determine whether the PGW-U has detached from the first user plane serving gateway SGW-U based on the address of the first SGW-C and the preset address in the following manner: if the preset address includes the address of the first SGW-C, the PGW-C determines that the PGW-U has not detached from the first SGW-U, or if the preset address does not include the address of the first SGW-C, the PGW-C determines that the PGW-U has detached from the first SGW-U.

[0046] In a possible design, when the PGW-C determines that the PGW-U has detached from the first SGW-U, the PGW-C initiates re-establishment of a PDN connection to the terminal device.

[0047] When the PGW-C determines that the PGW-U is detached from the first SGW-U, the PGW-C initiates re-establishment of a PDN connection to the terminal device, optionally, when the terminal device has no traffic within a specified time, the PGW-C initiates re-establishment of a PDN connection to the terminal device. In this way, the impact on ongoing data and voice services can be avoided.

[0048] In a possible design, when initiating re-establishment of a PDN connection to the terminal device, the PGW-C may send a delete bearer request to the MME, where the delete bearer request carries information about the delete cause, and the information about the delete cause indicates that reactivation is requested. The terminal device can be reactivated by carrying the information about the delete cause. In the activation process, the PGW-C selects a combined SGW-U / PGW-U for the terminal device, so that the user plane network elements can be combined and the path for forwarding data or voice traffic is better.

[0049] According to a fourth aspect, a method for determining disassociation between user plane network elements is provided. The method may be performed by a first control plane network element or may be performed by a component of the first control plane network element. The first control plane network element may be an I-SMF. For example, the method is performed by the I-SMF. The method may be implemented by using the following steps: the I-SMF obtains an address of the first SMF, and the I-SMF determines whether the I-UPF is disassociated from the first PSA-UPF or whether to initiate re-establishment of a PDU session of a terminal device based on the address of the first SMF and the preset address.

[0050] The preset address includes the addresses of one or more SMFs located in the same area as the I-SMF, where the first PSA-UPF is a user plane anchor for the terminal device, and the first SMF is a control plane anchor for the terminal device.

[0051] In a possible design, when the I-SMF determines that the I-UPF has separated from the first PSA-UPF based on the address of the first SMF and the preset address, the I-SMF may trigger re-establishment of a PDU session of the terminal device.

[0052] In a possible design, the I-SMF may determine whether the I-UPF has separated from the first PSA-UPF based on the address of the first SMF and the preset address in the following manner: if the preset address includes the address of the first SMF, the I-SMF determines that the I-UPF has not separated from the first PSA-UPF, or if the preset address does not include the address of the first SMF, the I-SMF determines that the I-UPF has separated from the first PSA-UPF.

[0053] When the I-SMF determines that the I-UPF is dissociated from the first PSA-UPF based on the address of the first SMF and the preset address, the I-SMF triggers the re-establishment of the PDU session of the terminal device, optionally, the I-SMF initiates the re-establishment of the PDU session of the terminal device when the N1 / N2 connection to the terminal device is released. In this way, the impact on ongoing data and voice services can be avoided. Furthermore, optionally, the I-SMF may start a timer when the N1 / N2 connection to the terminal device is released, and initiate the re-establishment of the PDU session of the terminal device after the timer has elapsed. Since the timer is started when the N1 / N2 connection to the terminal device is released, the impact on ongoing data and voice services can be avoided.

[0054] According to a fifth aspect, there is provided a method for determining disassociation between user plane network elements. The method may be executed by a first control plane network element or may be executed by a component of the first control plane network element. The first control plane network element may be an SMF. For example, the method is executed by the SMF. The method may be implemented by using the following steps: the SMF obtains an address of a first I-SMF, the SMF determines whether the PSA-UPF has disassociated from the first I-UPF or whether to initiate a re-establishment of a PDU session of the terminal device based on the address of the first I-SMF and a preset address, the preset address includes an address of one or more I-SMFs located in the same area as the SMF, the PSA-UPF may be a user plane anchor of the terminal device, and the SMF may be a control plane anchor of the terminal device.

[0055] In a possible design, the SMF may determine whether the PSA-UPF has separated from the 1I-UPF based on the address of the 1I-SMF and the preset address in the following manner: if the preset address includes the address of the 1I-SMF, the SMF determines that the PSA-UPF has not separated from the 1I-UPF, or if the preset address does not include the address of the 1I-SMF, the SMF determines that the PSA-UPF has separated from the 1I-UPF.

[0056] In a possible design, when the SMF determines that the PSA-UPF has separated from the first I-UPF, the SMF initiates re-establishment of a PDU session of the terminal device.

[0057] When the SMF determines that the PSA-UPF is separated from the first I-UPF, the SMF initiates re-establishment of the PDU session of the terminal device, optionally, when the terminal device has no traffic within a specified time, the SMF initiates re-establishment of the PDU session of the terminal device. In this way, the impact on ongoing data and voice services can be avoided.

[0058] According to a sixth aspect, there is provided a communication apparatus. The apparatus may be a first control plane network element or a component (e.g., a chip, a chip system, or a circuit) of the first control plane network element. The first control plane network element includes a serving gateway for control plane SGW-C (which may be denoted as first SGW-C), a data network PDN gateway for control plane PGW-C (which may be denoted as first PGW-C), a session management function network element SMF, or an intermediate session management function network element I-SMF. The apparatus comprises functionality for performing a method according to the first aspect or any one of the possible designs of the first aspect. The functionality may be implemented by hardware or by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above functionality. In the design, the apparatus may include an obtaining unit and a determining unit. For example, the obtaining unit is configured to obtain a first node identifier of the first user plane network element and a second node identifier of the second user plane network element. The first user plane network element is a user plane anchor. The determining unit is configured to determine whether the first user plane network element is isolated from the second user plane network element based on the first node identifier and the second node identifier.

[0059] In a possible design, when acquiring the first node identifier of the first user plane network element, the acquiring unit is configured to acquire the first node identifier of the first user plane network element from a second control plane network element, where the device is an SGW-C and the first user plane network element is a data network PDN gateway for a first user plane PGW-U, or the device is a PGW-C and the first user plane network element is a serving gateway for a first user plane SGW-U, or the device is an SMF and the first user plane network element is an intermediate user plane management function I-UPF, or the device is an I-SMF and the first user plane network element is a protocol data unit session anchor user plane management function PSA-UPF.

[0060] In a possible design, when determining whether the first user plane network element is detached from the second user plane network element based on the first node identifier and the second node identifier, the determination unit is configured to: determine that the first user plane network element is not detached from the second user plane network element if the first node identifier is the same as the second node identifier, or determine that the first user plane network element is detached from the second user plane network element if the first node identifier is different from the second node identifier.

[0061] In a possible design, when determining whether the first user plane network element is separated from the second user plane network element based on the first node identifier and the second node identifier, the determination unit is configured to determine that the first user plane network element is not separated from the second user plane network element if the first information in the first node identifier is the same as the second information in the second node identifier, or to determine that the first user plane network element is separated from the second user plane network element if the first information in the first node identifier is different from the second information in the second node identifier, where the first information indicates an area in which the first user plane network element is located and the second information indicates an area in which the second user plane network element is located.

[0062] In a possible design, when determining whether the first user plane network element is detached from the second user plane network element based on the first node identifier and the second node identifier, the determination unit is configured to determine that the first user plane network element is not detached from the second user plane network element if the first node identifier and the second node identifier are in the same group, or to determine that the first user plane network element is detached from the second user plane network element if the first node identifier and the second node identifier are not in the same group.

[0063] In a possible design, the apparatus further includes a re-establishment unit configured to initiate re-establishment of a data transmission path of the terminal device when the determination unit determines that the first user plane network element is separated from the second user plane network element.

[0064] In a possible design, the apparatus is an SGW-C. When initiating re-establishment of a data transmission path of the terminal device, the re-establishment unit is configured to initiate re-establishment of a packet data network PDN connection to the terminal device when an S1 connection to the terminal device is released.

[0065] In a possible design, the device is an I-SMF. When initiating re-establishment of a data transmission path of the terminal device, the re-establishment unit is configured to initiate re-establishment of a protocol data unit PDU session of the terminal device when the N1 / N2 connection to the terminal device is released.

[0066] In a possible design, the device is a PGW-C or an SMF. When initiating re-establishment of a data transmission path of a terminal device, the re-establishment unit is configured to initiate re-establishment of the data transmission path of the terminal device when the terminal device has no traffic within a specified time.

[0067] For the advantageous effects of the sixth aspect and possible designs, please refer to the description of the first aspect and possible designs. The details will not be described again here.

[0068] According to a seventh aspect, a communication apparatus is provided. The apparatus may be a serving gateway for control plane SGW-C or may be a component of a serving gateway for control plane SGW-C. The serving gateway for control plane SGW-C and the first data network PDN gateway for control plane PGW-C are located in different control plane gateway nodes. The apparatus comprises functionality for implementing a method according to the second aspect or any one of the possible designs of the second aspect. The functionality may be implemented by hardware or by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above functionality. In a design, the apparatus may include an obtaining unit and a determining unit.

[0069] For example, the acquisition unit is configured to acquire an address of a first PGW-C, and the determination unit is configured to determine whether a serving gateway for user plane SGW-U has disassociated from the first PGW-U based on the address of the first PGW-C and the preset address, or the determination unit is configured to determine whether a PDN connection of the terminal device should be re-established based on the address of the first PGW-C and the preset address, where the preset address includes addresses of one or more PGW-C located in the same area as the SGW-C, the first PGW-U is a user plane anchor for the terminal device to access the PDN, and the first PGW-C is a control plane anchor for the terminal device to access the PDN.

[0070] In a possible design, when the determination unit determines whether the serving gateway for user plane SGW-U has detached from the first PGW-U based on the address of the first PGW-C and the preset address, the determination unit is particularly configured to determine, for the SGW-C, that the SGW-U has not detached from the first PGW-U if the preset address includes the address of the first PGW-C, or to determine, for the SGW-C, that the SGW-U has detached from the first PGW-U if the preset address does not include the address of the first PGW-C.

[0071] In a possible design, the apparatus further includes a re-establishment unit configured to initiate re-establishment of a PDN connection to the terminal device when the determination unit determines that the SGW-U is detached from the first PGW-U.

[0072] Optionally, the re-establishment unit is further configured to initiate re-establishment of a PDN connection to the terminal device when the S1 connection to the terminal device is released.

[0073] Optionally, the re-establishment unit may be further configured to start a timer when the S1 connection to the terminal device is released, and to initiate re-establishment of a PDN connection to the terminal device after the timer has elapsed.

[0074] For the advantageous effects of the seventh aspect and possible designs, please refer to the second aspect and possible designs description, and the details will not be described again here.

[0075] According to an eighth aspect, there is provided a communication apparatus. The apparatus may be a PGW-C or may be a component of a PGW-C. A serving gateway for control plane SGW-C and a first data network PDN gateway for control plane PGW-C are located in different control plane gateway nodes. The apparatus comprises functionality for implementing a method according to the third aspect or any one of the possible designs of the third aspect. The functionality may be implemented by hardware or by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above functions. In a design, the apparatus may include an obtaining unit and a determining unit. For example, the acquisition unit is configured to acquire an address of a first SGW-C, and the determination unit is configured to determine whether the PGW-U is separated from a first serving gateway for user plane SGW-U based on the address of the first SGW-C and the preset address, where the preset address includes addresses of one or more SGW-C located in the same area as the PGW-C, the PGW-U is a user plane anchor for terminal devices to access the PDN, and the PGW-C is a control plane anchor for terminal devices to access the PDN.

[0076] In a possible design, when determining whether the PGW-U has detached from the first user plane serving gateway SGW-U based on the address of the first SGW-C and the preset address, the determination unit is particularly configured to determine, for the PGW-C, that the PGW-U has not detached from the first SGW-U if the preset address includes the address of the first SGW-C, or to determine, for the PGW-C, that the PGW-U has detached from the first SGW-U if the preset address does not include the address of the first SGW-C.

[0077] In a possible design, the apparatus further includes a re-establishment unit configured to initiate re-establishment of a PDN connection to the terminal device when the determination unit determines that the PGW-U is detached from the first SGW-U.

[0078] Optionally, the re-establishment unit may be further configured to initiate a re-establishment of a PDN connection to the terminal device when the terminal device has no traffic within a specified time.

[0079] For the advantageous effects of the eighth aspect and possible designs, please refer to the third aspect and possible designs description, and the details will not be described again here.

[0080] According to a ninth aspect, a communication device is provided. The device may be an I-SMF or a component of an I-SMF. The device comprises a function for implementing a method according to the fourth aspect or any one of the possible designs of the fourth aspect. The function may be implemented by hardware or by executing corresponding software by the hardware. The hardware or software includes one or more modules corresponding to the above functions. In a design, the device may include an acquisition unit and a determination unit. For example, the acquisition unit is configured to acquire an address of a first SMF, and the determination unit is configured to determine whether the I-UPF has dissociated from the first PSA-UPF or whether to initiate a re-establishment of a PDU session of the terminal device based on the address of the first SMF and the preset address. The preset address includes addresses of one or more SMFs located in the same area as the I-SMF, the first PSA-UPF being a user plane anchor of the terminal device, and the first SMF being a control plane anchor of the terminal device.

[0081] In a possible design, the apparatus further includes a re-establishment unit, which is configured to trigger re-establishment of a PDU session of the terminal device when the determination unit determines, based on the address of the first SMF and the preset address, that the I-UPF is separated from the first PSA-UPF.

[0082] In a possible design, when determining whether the I-UPF is separated from the first PSA-UPF based on the address of the first SMF and the preset address, the determination unit is particularly configured to determine, for the I-SMF, that the I-UPF is not separated from the first PSA-UPF if the preset address includes the address of the first SMF, or to determine, for the I-SMF, that the I-UPF is separated from the first PSA-UPF if the preset address does not include the address of the first SMF.

[0083] When the determining unit determines, based on the address of the first SMF and the preset address, that the I-UPF is dissociated from the first PSA-UPF, the re-establishing unit triggers the re-establishment of the PDU session of the terminal device. Optionally, the re-establishing unit may be configured to initiate the re-establishment of the PDU session of the terminal device when the N1 / N2 connection to the terminal device is released. In this way, the impact on ongoing data and voice services can be avoided. Furthermore, optionally, the re-establishing unit may be further configured to start a timer when the N1 / N2 connection to the terminal device is released, and to start the re-establishment of the PDU session of the terminal device after the timer has elapsed. Since the timer is started when the N1 / N2 connection to the terminal device is released, the impact on ongoing data and voice services can be avoided.

[0084] According to a tenth aspect, a communication device is provided. The device may be an SMF or a component of an SMF. The device comprises a function for implementing a method according to the fifth aspect or any one of the possible designs of the fifth aspect. The function may be implemented by hardware or by executing corresponding software by the hardware. The hardware or software includes one or more modules corresponding to the above functions. In a design, the device may include an acquisition unit and a determination unit. For example, the acquisition unit is configured to acquire an address of a first I-SMF, and the determination unit is configured to determine whether the PSA-UPF has dissociated from the first I-UPF or whether to initiate a re-establishment of a PDU session of the terminal device based on the address of the first I-SMF and a preset address, the preset address including addresses of one or more I-SMFs located in the same area as the SMF, the PSA-UPF may be a user plane anchor of the terminal device, and the SMF may be a control plane anchor of the terminal device.

[0085] In a possible design, when determining whether the PSA-UPF is separated from the 1I-UPF based on the address of the 1I-SMF and the preset address, the determination unit is specifically configured to determine that the PSA-UPF is not separated from the 1I-UPF if the preset address includes the address of the 1I-SMF, or to determine that, for an SMF, the PSA-UPF is separated from the 1I-UPF if the preset address does not include the address of the 1I-SMF.

[0086] In a possible design, the apparatus further includes a re-establishment unit configured to initiate re-establishment of a PDU session of the terminal device when the determination unit determines that the PSA-UPF is separated from the first I-UPF.

[0087] When the determining unit determines that the PSA-UPF is separated from the first I-UPF, the re-establishing unit initiates re-establishment of the PDU session of the terminal device, and optionally, the re-establishing unit may be further configured to initiate re-establishment of the PDU session of the terminal device when the terminal device has no traffic within a specified time. In this way, the impact on ongoing data and voice services can be avoided.

[0088] According to an eleventh aspect, an embodiment of the present application provides a communication device. The communication device includes an interface circuit and a processor, the processor and the interface circuit being coupled to each other. The processor is configured to perform the method described in the above aspects and possible designs of the aspects by using logic circuits or executing code instructions. The interface circuit is configured to receive a signal from a communication device other than the communication device and send the signal to the processor or send a signal from the processor to the communication device other than the communication device. The interface circuit may be a transceiver or an input / output interface.

[0089] Optionally, the communication device may further include a memory configured to store instructions to be executed by the processor, or to store input data required for execution of the instructions by the processor, or to store data generated after the processor executes the instructions. The memory may be a physically separate unit or may be coupled to the processor, or the processor may include the memory.

[0090] According to a twelfth aspect, an embodiment of the present application provides a computer readable storage medium storing a computer program or readable instructions, which, when executed by a communication device, performs a method of any of the above aspects or possible designs of the aspects.

[0091] According to a thirteenth aspect, an embodiment of the present application provides a chip system. The chip system includes a processor and may further include a memory. The memory is configured to store a program, instruction, or code. The processor is configured to execute the program, instruction, or code stored in the memory to perform the method of the above aspect or the possible design of the jobber aspect. The chip system may include a chip, or may include a chip and other discrete components.

[0092] According to a fourteenth aspect there is provided a computer program product comprising instructions, when the computer program product is executed by a communications device a method of the above aspect or possible designs of the above aspect is performed.

[0093] According to a fifteenth aspect there is provided a communication system, the system including a first control plane network element, a first user plane network element and a second user plane network element, the first control plane network element configured to perform a method of any of the above aspects or possible designs of the above aspects.

[0094] In a possible design, the system includes a second control plane network element, which may be configured to perform operations performed by the second control plane network element in the above aspect or a possible design of the above aspect. [Brief description of the drawings]

[0095] [Figure 1a] FIG. 1 is a schematic diagram of a CUPS EPC network architecture according to an embodiment of the present application. [Figure 1b] FIG. 1 is a schematic diagram of the architecture of a communication system according to an embodiment of the present application; [Figure 2a] 1 is a schematic flowchart 1 of a method for determining isolation between user plane network elements according to an embodiment of the present application; [Figure 2b] 2 is a schematic flowchart 2 of a method for determining isolation between user plane network elements according to an embodiment of the present application; [Figure 2c] 3 is a schematic flowchart 3 of a method for determining isolation between user plane network elements according to an embodiment of the present application; [Diagram 3] FIG. 1 is a schematic diagram of determining separation between user plane network elements according to an embodiment of the present application; [Figure 4] FIG. 2 is a schematic diagram of determining separation between user plane network elements according to an embodiment of the present application; [Diagram 5] 1 is a schematic flowchart 1 of PDN re-establishment according to an embodiment of the present application. [Figure 6] 2 is a schematic flowchart 2 of PDN re-establishment according to an embodiment of the present application. [Figure 7] 3 is a schematic flowchart 3 of PDN re-establishment according to an embodiment of the present application. [Figure 8] 4 is a schematic flowchart 4 of a method for determining isolation between user plane network elements according to an embodiment of the present application; [Figure 9] FIG. 3 is a schematic diagram of determining separation between user plane network elements according to an embodiment of the present application; [Figure 10] 5 is a schematic flowchart 5 of a method for determining isolation between user plane network elements according to an embodiment of the present application; [Figure 11] 1 is a schematic flowchart 1 of a method for determining separation between user plane network elements in a 5G communication system according to an embodiment of the present application; [Figure 12] 2 is a schematic flowchart 2 of a method for determining separation between user plane network elements in a 5G communication system according to an embodiment of the present application. [Figure 13] FIG. 1 is a schematic diagram of an operation procedure performed after a user plane network element is separated according to an embodiment of the present application; [Figure 14] FIG. 2 is a schematic diagram of an operation procedure performed after a user plane network element is separated according to an embodiment of the present application; [Figure 15] FIG. 3 is a schematic diagram of an operation procedure performed after a user plane network element is separated according to an embodiment of the present application; [Figure 16] 6 is a schematic flowchart 6 of a method for determining isolation between user plane network elements according to an embodiment of the present application. [Figure 17] 7 is a schematic flowchart 7 of a method for determining isolation between user plane network elements according to an embodiment of the present application; [Figure 18] 1 is a schematic diagram of a structure of a communication device according to an embodiment of the present application; [Figure 19] 1 is a schematic diagram of the structure of a communication device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0096] The embodiments of the present application provide a method and a communication device for determining separation between user plane network elements, to determine whether the user plane network elements are separated in a control and user plane separation scenario. The method and the device are conceived based on the same or similar technical concept. The method and the device have similar principles for solving problems. Therefore, the implementation of the device and the method should be mutually referenced. The repeated details will not be described.

[0097] In describing the embodiments of the present application, the character " / " generally indicates a "logical OR" relationship between related objects. Words such as "first", "second", and "third" are used for distinction and explanation only and cannot be understood as an indication or implication of relative importance or of order.

[0098] The method for determining isolation between user plane network elements provided in the embodiments of the present application may be applied to a 4th generation (4G) communication system, such as a long term evolution (LTE), or may be applied to a 5G communication system, such as a 5G new radio (NR), or may be applied to various future evolved communication systems, such as a 6th generation (6G) communication system or an eia-space-sea integrated communication system.

[0099] The following describes in detail the embodiments of the present application with reference to the accompanying drawings: Figure 1a and Figure 1b respectively show examples of a 4G communication system architecture and a 5G communication system architecture.

[0100] First, the architecture of a 4G communication system is used as an example for explanation.

[0101] 3GPP protocols describe an evolved packet core (EPC) network architecture, and data flow transmission between a terminal device and a server can be implemented based on the network architecture. In general, the EPC network architecture includes a serving gateway (SGW) and a packet data network (PDN) gateway (PGW). 3GPP protocols describe a control and user plane separation (CUPS) case in the EPC network architecture. Figure 1a shows a CUPS EPC network architecture. The method for determining separation between user plane gateways provided in the embodiments of the present application can be applied to the network architecture shown in Figure 1a. CUPS means that gateways are divided into control plane gateways and user plane gateways based on functions. As shown in Figure 1a, the SGW is divided into a serving gateway for user plane (SGW-U) and a serving gateway for control plane (SGW-C). The SGW-U may implement the user plane function of the SGW in a non-CUPS EPC network architecture, and the SGW-C may implement the control plane function of the SGW in a non-CUPS EPC network architecture. Similarly, the PGW is divided into a PDN gateway for user plane (PGW-U) and a PDN gateway for control plane (PGW-C).The PGW-U may implement the user plane functions of a PGW in a non-CUPS EPC network architecture, and the PGW-C may implement the control plane functions of a PGW in a non-CUPS EPC network architecture.

[0102] The EPC network architecture further includes a terminal device, which may also be called user equipment (UE), mobile station (MS), mobile terminal (MT), etc., and may be a device that provides voice or data connectivity to a user, or may be an Internet of Things device. For example, the terminal device may include a handheld device, a vehicle-mounted device, etc., that are equipped with wireless communication capabilities. The terminal device may be a mobile phone, a tablet computer, a notebook computer, a palmtop computer, a mobile internet device (MID), a wearable device (e.g., a smart watch, a smart band, or a pedometer), an in-vehicle device (e.g., an in-vehicle device of a car, a motorcycle, an electric car, an airplane, a ship, a train, or a high-speed rail), a virtual reality (VR) device, an augmented reality (AR) device, a wireless terminal in industrial control, a smart home device (e.g., for a refrigerator, a television, an air conditioner, or an electric meter), an intelligent robot, a workshop device, a wireless terminal in self driving, a wireless terminal in remote medical surgery, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, an aerial device (e.g., an intelligent robot, a hot air balloon, an unmanned aerial vehicle, or an airplane), etc. Alternatively, the terminal device may be another device having a terminal function, for example, a device that functions as a terminal in Internet of Vehicle communication.

[0103] Optionally, the EPC network architecture may further include a mobility management entity (MME) and a home subscriber server (HSS), where the MME is configured to manage a mobile context and a session context of a user equipment (UE). In addition, the EPC network architecture further includes monitoring network elements related to a monitoring function, such as a charging gateway (CG), an online charging system (OCS), and a lawful interception gateway (LIG). The PGW-C may implement monitoring of terminal services, such as charging and lawful interception for terminal services, by using these monitoring network elements.

[0104] In a CUPS session, the control plane network elements include SGW-C and PGW-C, and the user plane network elements include SGW-U and PGW-U. Usually, the control plane network elements (SGW-C and PGW-C) are centrally located in state capitals and regional centers, and the user plane network elements (SGW-U and PGW-U) are located in cities closer to users. This can shorten the service access path, improve the user's service experience, and save the transmission bandwidth on the bearer network.

[0105] How to determine whether user plane network elements are disjoint is a problem that needs to be solved. In a non-CUPS scenario, the MME may determine disjoint between the SGW and the PGW based on the canonical-node-names of the SGW and the PGW. Specifically, when the SGW changes during the movement of a terminal device, the MME selects a new SGW for the terminal. The MME obtains the hostname of the new SGW by querying based on the Tracking Area (TA) in which the terminal device is currently located. The MME extracts the canonical-node-name from the hostname of the new SGW and compares the canonical node name with the locally stored canonical node name of the PGW anchored by the terminal device. If the MME finds that the canonical node names of the SGW and the PGW are different or some fields in the area identified by the canonical node name are different, the MME considers the SGW to be disjoint from the PGW and triggers PDN re-establishment.

[0106] However, the way in which the MME determines the separation between user plane network elements in the non-CUPS scenario is not applicable to the CUPS scenario. In the CUPS scenario, the control plane network elements (SGW-C and PGW-C) and the user plane network elements (SGW-U and PGW-U) are located on different physical nodes. When selecting a gateway, the MME obtains the hostnames of the SGW-C and PGW-C based on the TA and the access point name (APN) by query, respectively, extracts the canonical node names from the hostnames, and finally obtains the interface internet protocol (IP) information of the SGW-C and PGW-C by query. The SGW-U and PGW-U are selected by the SGW-C and PGW-C, respectively, according to a specific rule. It can be seen that in the CUPS scenario, the canonical node names are used by the MME to select the control plane network elements (SGW-C and PGW-C) instead of the user plane network elements (SGW-U and PGW-U). Based on the canonical node names, the MME can only determine whether an SGW-C is detached from a PGW-C, but cannot determine whether an SGW-U is detached from a PGW-U.

[0107] When the same set of control plane network elements are connected to user plane network elements in multiple areas and the terminal device moves between these user plane network elements, the MME cannot accurately determine whether the SGW-U is detached from the PGW-U. For example, in a CUPS scenario, the network deployment principle in most areas is that the SGW-C and PGW-C are centrally deployed in large areas / state capitals, and correspondingly manage the area access across the state and all user plane network elements across the state, and the SGW-U and PGW-U are deployed in cities. In this scenario, when a user moves within a state, the control plane node where the SGW-C is located remains unchanged. The MME cannot determine whether the SGW-U is detached from the PGW-U by using a decision mechanism after the user moves.

[0108] The following describes the architecture of a 5G communication system based on the example of Figure 1b.

[0109] As shown in Figure 1b, the architecture of the communication system may include an access network and a core network. The core network mainly includes the following important logical network elements: an access and mobility management function network element, a session management function network element, a user plane function network element, a policy control function network element, an integrated data management function network element, etc. For example, Figure 1b shows a possible example of the architecture of the communication system, and the network elements or devices in the architecture of the communication system are illustrated by using concrete examples. Specifically, the architecture of the communication system shown in FIG. 1b may include a terminal device (a UE is used as an example), an access and mobility management function (AMF) network element, a session management function (SMF) network element, a user plane function (UPF) network element, a policy control function (PCF) network element, a unified data management function (UDM), an authentication server function (AUSF) network element, a network exposure function (NEF) network element, an application function (AF) network element, a network slice selection function (NSSF) network element, a (radio) access network ((R)AN) device, and a network repository function (NRF) network element.The AMF network element may be connected to the access network element through an N2 interface, the access network device may be connected to the UPF through an N3 interface, the SMF may be connected to the UPF through an N4 interface, and the AMF network element may be connected to the UE through an N1 interface. The interface names are merely examples for explanation. This is not particularly limited in the embodiment of the present application. It should be understood that the embodiment of the present application is not limited to the communication system shown in Figure 1b. The names of the network elements shown in Figure 1b are merely examples for explanation here and are not intended to limit the network elements included in the architecture of the communication system to which the communication method of the present application is applied.

[0110] The following describes in detail the functionality of some network elements or devices in the communication system of FIG. 1b.

[0111] For the description of the terminal device and the access network device, please refer to the description of Fig. 1a, and the details will not be described again here.

[0112] The access and mobility management function network element is mainly responsible for functions such as signaling processing, e.g., access control, mobility management, attachment and detachment, and gateway selection. When the AMF network element provides a service to a session in a terminal device, the AMF network element provides control plane storage resources for the session to store a session identifier, an SMF network element identifier associated with the session identifier, and the like. For example, in 5G, the access and mobility management function network element may be an AMF network element, e.g., as shown in FIG. 1b. In future communications, e.g., in 6G, the access and mobility management function network element may still be an AMF network element or have other names. This is not limited in the present application. When the access and mobility management function network element is an AMF network element, the AMF may provide Namf services.

[0113] The session management function network element is mainly responsible for session management in a mobile network, for example, establishing, modifying, and releasing a session. For example, specific functions include assigning an IP address to a user, selecting a UPF that provides a message forwarding function, etc. For example, in 5G, the session management function network element may be an SMF network element, for example, as shown in FIG. 1b. In future communications, for example, in 6G, the session management function network element may still be an SMF network element or have other names. This is not limited in this application. When the session management function network element is an SMF network element, the SMF may provide Namf services.

[0114] The user plane function network element is responsible for forwarding and receiving user data at the terminal device. The UPF network element may receive user data from the data network and transmit the user data to the terminal device via the access network device. The UPF network element may further receive user data from the terminal device via the access network device and forward the user data to the data network. The transmission resources and scheduling functions used by the UPF network element to provide services to the terminal device are managed and controlled by the SMF network element. For example, in 5G, the user plane function network element may be a UPF network element, for example as shown in FIG. 1b. In future communications, for example in 6G, the user plane function network element may still be a UPF network element or have another name. This is not limited in the present application.

[0115] It should be noted that the architecture of the communication system shown in Fig. 1b is not limited to including only the network elements shown in the figure, and may further include other devices shown in Fig. 1b. Details will not be described one by one here in this application. The distribution form of the network elements is not limited in the embodiment of this application. The distribution form shown in Fig. 1a and Fig. 1b is only an example. This is not limited in this application.

[0116] Each network element in the core network may also be referred to as a functional entity or device, and may be a network element implemented on dedicated hardware, or a software instance running on dedicated hardware, or an instance with functionality virtualized on a suitable platform, for example a virtualization platform may be a class and platform.

[0117] For ease of explanation, the network element shown in Fig. 1b is used as an example for explanation hereinafter in this application, and the XX network element is directly called XX. It should be understood that the names of all network elements in this application are used only as examples, and may be called by other names in future communications, or the network elements in this application may be replaced by other entities or devices having the same functions in future communications. This is not limited in this application. A unified description is given here. Details will not be described again below.

[0118] Based on the communication system shown in FIG. 1b, the control plane network element may be an SMF, and the user plane anchor gateway may be a PDU session anchor UPF (PSA-UPF). When the terminal device goes out of the coverage area of ​​the PSA-UPF, the SMF selects an intermediate UPF (I-UPF) based on the location of the terminal device, and inserts an intermediate UPF between the access network device and the PSA-UPF for relaying to implement end-to-end network communication. The SMF needs to determine whether the PSA-UPF is separated from the I-UPF. When the terminal device goes out of the SMF service range, the AMF network element selects to insert an intermediate SMF (I-) based on the location of the terminal device, and the I-SMF selects the I-UPF for relaying. The I-SMF or the SMF needs to determine whether the PSA-UPF is separated from the I-UPF.

[0119] Based on this, an embodiment of the present application provides a method for determining isolation between user plane network elements in a control and user plane separation scenario, to determine isolation between user plane network elements.

[0120] As shown in FIG. 2a, a specific procedure of the method for determining isolation between user plane network elements provided in an embodiment of the present application is as follows: the method may be performed by a first control plane network element, and the first control plane network element may be an SGW-C, a PGW-C, an SMF, or an I-SMF.

[0121] S201a: A first control plane network element obtains a first node identifier of a first user plane network element and a second node identifier of a second user plane network element.

[0122] The first user plane network element is a user plane anchor.

[0123] S202a: The first control plane network element determines, based on the first node identifier and the second node identifier, whether the user plane network elements are disjoint, i.e., whether the first user plane network element is disjoint from the second user plane network element.

[0124] In the present application, whether a user plane network element is detached may also be understood as determining whether a data transmission path connection to a terminal device should be re-established, or determining whether a traffic forwarding path (or data transmission path) should be optimized, or determining whether a traffic diversion (or data transmission diversion) exists. For example, the first control plane network element may determine whether the first user plane network element is detached from the second user plane network element based on the first node identifier and the second node identifier, and further perform the operation performed after the detachment, for example, re-establishment of a data transmission path connection to the terminal device, when determining that the user plane network element is detached. Alternatively, the first control plane network element may directly determine whether a data transmission path connection to the terminal device should be re-established based on the first node identifier and the second node identifier, and re-establish the data transmission path when the first control plane network element determines that the data transmission path connection to the terminal device is re-established. As another example, the first control plane network element may determine whether a traffic diversion exists based on the first node identifier and the second node identifier, and upon determining that a traffic diversion exists, perform an action, such as re-establishing a data transmission path for the terminal device.

[0125] In the embodiment of FIG. 2a, the first control plane network element determines whether the user plane network elements are separated based on the node identifiers of the two user plane network elements, so that whether the user plane network elements are separated can be determined in a control and user plane separation scenario, and the efficiency and accuracy of determining separation between user plane network elements can be improved, so that measures can be taken in a timely manner when the user plane gateway is separated to avoid traffic diversion.

[0126] Optionally, in S201a, the first control plane network element acquires a first node identifier of the first user plane network element and a second node identifier of the second user plane network element. The first control plane network element may locally acquire the node identifier of one user plane network element and acquire the node identifier of another user plane network element from the second control plane network element. Based on different types of the first control plane network element, the following provides separate descriptions by using examples. For example, the first control plane network element is an SGW-C, and the SGW-C may acquire the node identifier of the first PGW-U from the PGW-C. As another example, the first control plane network element is a PGW-C, and the PGW-C may acquire the node identifier of the first SGW-U from the SGW-C. As another example, the first control plane network element is an SMF, and when the I-SMF is not inserted, the first control plane network element may locally acquire the node identifiers of the two user plane network elements. As another example, the first control plane network element may be an SMF, and the SMF may obtain a node identifier of the first I-UPF from the I-SMF when the I-SMF is inserted. As another example, the first control plane network element may be an I-SMF, and the I-SMF may obtain a node identifier of the first PSA-UPF from the SMF.

[0127] Based on the embodiment of FIG. 2a, the following will separately describe a corresponding method for determining isolation between user plane network elements when the first control plane network element is a different network element.

[0128] As shown in FIG. 2b, when the first control plane network element is an SGW-C or a PGW-C, the procedure of the method for determining separation between user plane network elements is as follows:

[0129] S201b: The first control plane network element obtains a node identifier of the first PGW-U and a node identifier of the first SGW-U.

[0130] The first PGW-U is a user plane anchor through which the terminal device accesses the PDN. 3GPP specifies that the PGW-U cannot be changed during the movement of the terminal device, and the first PGW-U is a user plane anchor of the terminal device, and the first PGW-U cannot be changed during the movement process of the terminal device.

[0131] S202b: The first control plane network element determines, based on the node identifier of the first PGW-U and the node identifier of the first SGW-U, whether the first SGW-U is detached from the first PGW-U.

[0132] In the embodiment of FIG. 2b, the first control plane network element determines whether the first SGW-U is disassociated from the first PGW-U based on the node identifier of the first PGW-U and the node identifier of the first SGW-U, so that whether the user plane network element is disassociated can be determined in a CUPS scenario, and the efficiency and accuracy of determining disassociation between user plane network elements can be improved, so that measures can be taken in a timely manner when the user plane network element is disassociated to avoid traffic diversion.

[0133] As shown in FIG. 2c, when the first control plane network element is an I-SMF or an SMF, the procedure of the method for determining separation between user plane network elements is as follows:

[0134] S201c: The first control plane network element obtains a node identifier of the first PSA-UPF and a node identifier of the first I-UPF.

[0135] The first PSA-UPF is a user plane anchor through which a terminal device accesses a data network (DN). The first PSA-UPF is a user plane anchor for a terminal device.

[0136] S202c: The first control plane network element determines whether the first I-UPF is disassociated from the first PSA-UPF based on the node identifier of the first PSA-UPF and the node identifier of the first I-UPF.

[0137] In the embodiment of Figure 2c, the first control plane network element determines whether the first I-UPF is separated from the first PSA-UPF based on the node identifier of the first PSA-UPF and the node identifier of the first I-UPF, so that whether the user plane network element is separated can be determined in a control and user plane separation scenario, and the efficiency and accuracy of determining separation between user plane network elements can be improved, so that measures can be taken in a timely manner when the user plane network element is separated to avoid traffic diversion.

[0138] The following describes some possible implementations based on the embodiment of FIG. 2b.

[0139] The first control plane network element may be an SGW-C or a PGW-C, and the SGW-C may be an SGW-C reselected by the MME for a terminal device when the terminal device moves. The first SGW-U is an SGW-U reselected by the SGW-C for a terminal device. The PGW-C is a control plane anchor through which the terminal device accesses the PDN. 3GPP protocols specify that the PGW-C cannot be changed during the movement of the terminal device.

[0140] According to the definition of the 3GPP TS 29.244 protocol, when the gateway is deployed in the CUPS, the control plane network element and the user plane network element are interconnected via the Sx interface and identified by node identifiers (Node IDs). That is, during the CUPS deployment, the SGW-C can obtain the node identifier of the SGW-U via the Sx interface, and the PGW-C can obtain the node identifier of the PGW-U via the Sx interface. When the terminal device moves between areas, the MME reselects the SGW-U based on the current location of the terminal device and records the node identifier of the SGW-U where the terminal device is located. The PGW-C and the PGW-U are anchored and unchanged during the movement of the terminal device. It can be seen that the SGW-C knows the second node identifier of the first SGW-U, and the PGW-C knows the first node identifier of the first PGW-U.

[0141] The following describes an optional implementation in which the first control plane network element obtains the first node identifier and the second node identifier in S201b.

[0142] When the first control plane network element is an SGW-C, the SGW-C knows the second node identifier of the first SGW-U (e.g., the SGW-C obtains the second node identifier of the first SGW-U from local storage), and the SGW-C may obtain the first node identifier of the first PGW-U from the PGW-C.

[0143] When the first control plane network element is a PGW-C, the PGW-C knows the first node identifier of the first PGW-U (e.g., the PGW-C obtains the first node identifier of the first PGW-U from local storage), and the PGW-C may obtain the second node identifier of the first SGW-U from the SGW-C.

[0144] The following describes separately an optional implementation in which the first control plane network element acquires a first node identifier when the first control plane network element is an SGW-C, and an optional implementation in which the first control plane network element acquires a second node identifier when the first control plane network element is a PGW-C.

[0145] The SGW-c and the PGW-C may be integrated or separated. The SGW-C and the PGW-C are integrated, meaning that the SGW-C and the PGW-C are located in the same control plane network element node. The SGW-C and the PGW-C are separated, meaning that the SGW-C and the PGW-C are located in different control plane network element nodes. For example, when the SGW-C and the PGW-C are integrated, the node identifiers of the SGW-C and the PGW-C may be the same, and when the SGW-C and the PGW-C are separated, the node identifiers of the SGW-C and the PGW-C may be different. The control plane network element may also be called a physical device, a physical node, or a functional network element. The control plane network element node may be a network element implemented on dedicated hardware, or may be a software instance running on dedicated hardware, or may be an instance with functions virtualized on a suitable platform. For example, the virtualization platform may be a cloud platform. The control plane network element is, for example, a centralized gateway (CGW).

[0146] When the SGW-C and the PGW-C are located in the same control plane network element node, the SGW-C can obtain the first node identifier of the first PGW-U from the local PGW-C, where the local PGW-C is the control plane network element node. The PGW-C can forward the first node identifier to the SGW-C by using the internal signaling of the control plane network element node, and the SGW-C can obtain the first node identifier from the PGW-C by using the internal signaling of the control plane network element node.

[0147] Similarly, when the SGW-C and the PGW-C are located in the same control plane network element node, the PGW-C can obtain the second node identifier of the first SGW-U from the local SGW-C, where the local SGW-C is the control plane network element node. The SGW-C can forward the second node identifier to the PGW-C by using the internal signaling of the control plane network element node, and the PGW-C can obtain the second node identifier from the SGW-C by using the internal signaling of the control plane network element node.

[0148] When the SGW-C and the PGW-C are located in different control plane network element nodes, the PGW-C may obtain the second node identifier of the first SGW-U by exchanging messages with the SGW-C. Optionally, the SGW-C may send a Modify Bearer Request message to the PGW-C, where the Modify Bearer Request message may carry the second node identifier of the first SGW-U. The PGW-C receives the Modify Bearer Request message from the SGW-C and obtains the second node identifier of the first SGW-U from the Modify Bearer Request message.

[0149] Similarly, when the SGW-C and the PGW-C are located in different control plane network element nodes, the SGW-C may obtain the first node identifier of the first PGW-U by exchanging messages with the PGW-C. Optionally, the PGW-C may send a Modify Bearer Response message to the SGW-C, where the Modify Bearer Response message carries the first node identifier of the first PGW-U. The SGW-C receives the Modify Bearer Response message from the PGW-C, and the SGW-C obtains the first node identifier of the first PGW-U from the Modify Bearer Response message. According to the 3GPP 29.274 protocol, when the terminal device moves, the SGW is reselected, and the new SGW-C sends a Modify Bearer Request message to the PGW-C anchored by the terminal device, where the Modify Bearer Request message can be used to update the local IP address and the TEID of the GTP tunnel. The PGW-C returns a modify bearer response message to the SGW-C, and the modify bearer response message carries a local IP address and a tunnel endpoint identifier (TEID) of the GPRS Tunneling Protocol (GTP) tunnel to complete the S5 / S8 path switching. In this embodiment of the present application, when the SGW-C and the PGW-C are located in different control plane network element nodes and the SGW-C obtains the first node identifier, the SGW-C can extend the modify bearer response message in the 3GPP 29.274 protocol, add a first private information element that can indicate the first node identifier of the first PGW-U to the modify bearer response message sent by the PGW-C to the SGW-C, and stuff the first node identifier of the first PGW-U into the first private information element of the modify bearer response message. In this way, the SGW-C obtains the first node identifier of the first PGW-U from the modify bearer response message.When the SGW-C and the PGW-C are located in different control plane network element nodes and the PGW-C obtains the second node identifier, the PGW-C may extend the modify bearer request message in the 3GPP 29.274 protocol, add a second private information element, which may indicate the second node identifier of the first SGW-U, to the modify bearer request message sent by the SGW-C and the PGW-C to the PGW-C, and pack the second node identifier of the first SGW-U into the second private information element of the modify bearer request message. In this way, the PGW-C may obtain the second node identifier of the first SGW-U from the bearer request message.

[0150] The following describes some possible implementations based on the embodiment of FIG. 2c.

[0151] The following describes an optional implementation in which the first control plane network element obtains the node identifier of the first PSA-UPF and the node identifier of the first I-UPF in S201c.

[0152] The first control plane network element may be an SMF or an I-SMF.

[0153] When the first control plane network element is an I-SMF, the I-SMF knows the node identifier of the first I-UPF (e.g., the I-SMF obtains the node identifier of the first I-UPF from local storage), and the I-SMF may obtain the node identifier of the first PSA-UPF from the SMF.

[0154] When the first control plane network element is an SMF, in a scenario where an I-SMF is not inserted, the SMF may locally obtain the node identifier of the first PSA-UPF and the node identifier of the first I-UPF.

[0155] When the first control plane network element is an SMF, in a scenario where an I-SMF is inserted, the SMF knows the node identifier of the first PSA-UPF (e.g., the SMF obtains the node identifier of the first PSA-UPF from local storage), and the SMF may obtain the node identifier of the first I-UPF from the I-SMF.

[0156] The following describes separately an optional implementation in which the first control plane network element acquires a first node identifier when the first control plane network element is an I-SMF and an optional implementation in which the first control plane network element acquires a second node identifier when the first control plane network element is an SMF.

[0157] When the I-SMF is inserted, the SMF may obtain a node identifier of the first I-UPF by exchanging messages with the I-SMF. Optionally, the I-SMF may send a PDU Session Create Request (Nsmf_PDUSession_Create Request) message to the SMF, and the PDU Session Create Request message may carry the node identifier of the first I-UPF. The SMF receives the PDU Session Create Request message from the I-SMF and obtains the node identifier of the first I-UPF from the PDU Session Create Request message.

[0158] When the I-SMF is inserted, the I-SMF may obtain the node identifier of the first PSA-UPF by exchanging messages with the SMF. Optionally, the SMF may send a PDU session create response (Nsmf_PDUSession_Create Response) message to the I-SMF, where the PDU session create response message carries the node identifier of the first PSA-UPF. The I-SMF receives the PDU session create response message from the SMF, and the I-SMF obtains the node identifier of the first PSA-UPF from the PDU session create response message. In this embodiment of the present application, when the I-SMF is inserted and the I-SMF obtains the first node identifier, the I-SMF may extend the PDU session create response message, add a private information element that may indicate the node identifier of the first PSA-UPF to the PDU session create response message sent by the SMF to the I-SMF, and stuff the node identifier of the first PSA-UPF into the private information element of the PDU session create response message. In this way, the I-SMF obtains the node identifier of the first PSA-UPF from the PDU session creation response message. When the I-SMF is inserted and the SMF obtains the node identifier of the first I-UPF, the SMF can extend the PDU session creation request message, add a private information element that may indicate the node identifier of the first I-UPF to the PDU session creation request message sent by the I-SMF to the SMF, and pack the node identifier of the first I-UPF into the private information element of the PDU session creation request message. In this way, the SMF can obtain the node identifier of the first I-UPF from the PDU session creation request message.

[0159] In summary, an optional implementation has been described in which a first control plane network element obtains a first node identifier and a second node identifier. The following describes an optional implementation in which a first control plane network element determines whether a first user plane network element is disjoint from a second user plane network element based on the first node identifier and the second node identifier.

[0160] Determination method 1: Whether the first user plane network element is separated from the second user plane network element is determined by determining whether the first node identifier is the same as the second node identifier.

[0161] For example, if the first node identifier is the same as the second node identifier, the first control plane network element determines that the first user plane network element is not isolated from the second user plane network element, or, if the first node identifier is different from the second node identifier, the first control plane network element determines that the first user plane network element is isolated from the second user plane network element.

[0162] Similar to the control plane network elements, the two user plane network elements SGW-U and PGW-U may also be integrated or separated. The two user plane network elements being integrated means that the two user plane network elements are located in the same user plane network element node. The two user plane network elements being separated means that the two user plane network elements are located in different user plane network element nodes.

[0163] An example in which the user plane network elements are an SGW-U and a PGW-U is used to describe decision method 1 in detail.

[0164] The SGW-U and the PGW-U are integrated means that the SGW-U and the PGW-U are located in the same user plane network element node. The SGW-U and the PGW-U are separated means that the SGW-U and the PGW-U are located in different control plane network element nodes. The user plane network element node may also be called a physical device, a physical node, or a functional network element. The user plane network element node may be a network element implemented on dedicated hardware, or may be a software instance running on dedicated hardware, or may be an instance with virtualized functions on a suitable platform. For example, the virtualization platform may be a cloud platform. The user plane network element node is, for example, a distributed gateway (DGW).

[0165] When the SGW-U and the PGW-U are located in the same user plane network element node, the SGW-U and the PGW-U use the same node identifier, and the respective node identifiers of the SGW-U and the PGW-U may be set to the name of the user plane network element node, the IP address of the user plane network element node, or other identifiers of the user plane network element node. When the first node identifier is different from the second node identifier, the SGW-U and the PGW-U are located in different user plane network element nodes, that is, the SGW-U is separated from the PGW-U. Therefore, in the determination method 1, whether the first SGW-U is separated from the first PGW-U can be determined by determining whether the first node identifier is the same as the second node identifier. This determination method is strict and accurate. Using the determination method 1 to determine the separation between user plane network elements may help improve the determination accuracy.

[0166] Determination method 2:

[0167] If the first information in the first node identifier is the same as the second information in the second node identifier, the first control plane network element determines that the first user plane network element is not isolated from the second user plane network element, or if the first information in the first node identifier is different from the second information in the second node identifier, the first control plane network element determines that the first user plane network element is isolated from the second user plane network element.

[0168] The first information indicates an area in which a first user plane network element is located, and the second information indicates an area in which a second user plane network element is located.

[0169] In this application, an area may be a geographic area or a region agreed upon between network elements or devices. The area may vary based on service requirements. The area may be at the granularity of a state, city, or county. For example, an area is City A in State A. As another example, an area is City B in State B.

[0170] In the determination method 2, whether the first user plane network element is separate from the second user plane network element is determined based on the information included in the node identifier and indicating the area. It can be understood that when the first user plane network element and the second user plane network element are located in different user plane gateway nodes, the first user plane network element and the second user plane network element may be located in the same area. In this case, although the first user plane network element and the second user plane network element are located in different user plane gateway nodes, when the determination method 2 is used, the first control plane network element determines that the first user plane network element is not separate from the second user plane network element.

[0171] When two user plane network elements are not in the same node but in the same area, the path transmission redundancy is not so large, and the demand for PDN re-establishment is not so high. In this determination method, whether a user plane network element is separated can be flexibly determined. Compared with the method of determining that a user plane network element is separated in a manner across user plane network elements, in this determination method, the user plane network element is determined to be separated only when an area spans between the user plane network elements, and further operations are performed after separation. This can avoid signaling consumption caused by unnecessary operations performed after separation.

[0172] For example, the two user plane network elements are SGW-U and PGW-U. In the determination method 2, the first node identifier and the second node identifier need to be named in a structured manner. Some fields, for example, the first information in the first node identifier that identifies the area and the second information in the second node identifier that identifies the area, identify the area.

[0173] Determination method 3:

[0174] If the first node identifier and the second node identifier are in the same group, the first control plane network element determines that the first user plane network element is not isolated from the second user plane network element, or if the first node identifier and the second node identifier are not in the same group, i.e., the first node identifier and the second node identifier are in different groups, the first control plane network element determines that the first user plane network element is isolated from the second user plane network element.

[0175] In this application, a "group" may also be referred to as a set, a list, or a combination. No. 1The user plane network element and the second user plane network element may be located in the same area, and the first control plane network element may pre-configure one or more groups, and the node identifiers of the first user plane network element and the second user plane network element located in the same area are set to the same group.

[0176] In the determination method 3, whether the first user plane network element is isolated from the second user plane network element is determined based on whether the first node identifier and the second node identifier are in the same group. It can be understood that even when the first user plane network element and the second user plane network element are located in different user plane gateway nodes, the node identifiers of the first user plane network element and the second user plane network element may be located in the same group. In this case, although the first user plane network element and the second user plane network element are located in different user plane gateway nodes, when the determination method 3 is used, the first control plane network element determines that the first user plane network element is not isolated from the second user plane network element.

[0177] When two user plane network elements are not in the same node but in the same area, the path transmission redundancy is not so large, and the demand for PDN re-establishment is not so high. In this determination method, whether a user plane network element is separated can be flexibly determined. Compared with the method of determining that a user plane network element is separated in a manner across user plane network elements, in this determination method, the user plane network element is determined to be separated only when an area spans between the user plane network elements, and further operations are performed after separation. This can avoid signaling consumption caused by unnecessary operations performed after separation.

[0178] When the two user plane network elements are SGW-U and PGW-U, the node identifiers do not need to be named in a structured manner in decision method 1 and decision method 3. If the node identifier is currently configured in the on-net device, the on-net device does not need to change the node identifier.

[0179] In summary, any implementation in which a first control plane network element determines whether a first user plane network element is isolated from a second user plane network element based on a first node identifier and a second node identifier is described, including determination method 1, determination method 2, and determination method 3.

[0180] The following describes Decision Method 1, Decision Method 2 and Decision Method 3 by using examples with reference to specific application scenarios.

[0181] Firstly, an application scenario in a 4G communication system is used as an illustrative example.

[0182] 3 shows two scenarios of the movement process of a terminal device. In scenario 1, the terminal device moves from a county in city A to a county in city A. In scenario 2, the terminal device moves from b county in city A to city B.

[0183] In a-county in City A, b-county in City A, and City B, SGW-U and PGW-U are both deployed in the same user plane gateway node. In a-county in City A, SGW-U1 and PGW-U1 are deployed in DGW1. In b-county in City A, SGW-U2 and PGW-U2 are deployed in DGW2. In City B, SGW-U3 and PGW-U3 are deployed in DGW3. a-county in City A, b-county in City A, and City B belong to State A. The control plane network elements are located in State A. SGW-C and PGW-C are deployed in the same control plane gateway node. In State A, SGW-C and PGW-C are deployed in CGW. The same set of control plane network elements is connected to user plane network elements in multiple areas. The SGW-C in State A is connected to SGW-U1, SGW-U2, and SGW-U3, and the PGW-C in State A is connected to PGW-U1, PGW-U2, and PGW-U3. Figure 3 further shows that the SGW-C in State A is connected to the MME.

[0184] From FIG. 3, it can be seen that in scenario 1, when the terminal device moves from a district in A city to b district in A city, SGW-U is reselected and changes from SGW-U1 to SGW-U2, and PGW-U1 is anchored and remains unchanged. Thus, SGW-U2 is located in DGW2, and PGW-U1 is located in DGW1. That is, SGW-U2 and PGW-U1 are located in different user plane gateway nodes. In scenario 2, when the terminal device moves from b district in A city to B city, SGW-U is reselected and changes from SGW-U2 to SGW-U3, and PGW-U2 is anchored and remains unchanged.

[0185] The control plane network element may determine whether the user plane network elements are separated through Determination Method 1 to Determination Method 3. The first control plane network element may be an SGW-C in State A or a PGW-C in State A.

[0186] When the first control plane network element determines whether the user plane network elements are separated in scenario 1 in decision method 1, the first control plane network element may determine whether the node identifier of SGW-U2 is the same as the node identifier of PGW-U1. For example, the node identifier of SGW-U2 is "DGW2" and the node identifier of PGW-U1 is "DGW1". If the first control plane network element determines by comparison that "DGW2" is different from "DGW1" (i.e., DGW2 ≠ DGW1), the first control plane network element considers that the SGW-U is separated from the PGW-U.

[0187] When the first control plane network element determines whether the user plane network element is isolated in scenario 1 in the determination method 2, the first control plane network element may determine whether the first information in the node identifier of the SGW-U2 is the same as the second information in the node identifier of the PGW-U1. If the first information in the node identifier of the SGW-U2 is the same as the second information in the node identifier of the PGW-U1, the user plane network element is not isolated. If the first information in the node identifier of the SGW-U2 is different from the second information in the node identifier of the PGW-U1, the user plane network element is isolated. For example, the node identifier of the SGW-U2 is "DGW2.cityA.provinceA", the first information indicating the area in which the SGW-U2 is located is "cityA.provinceA", the node identifier of the PGW-U1 is "DGW1.cityA.provinceA", and the second information indicating the area in which the PGW-U1 is located is "cityA.provinceA". The first information is the same as the second information. In this case, the first control plane network element determines that the user plane network element is not isolated. It can be seen that the results of determining whether the user plane network element is isolated in scenario 1 by the first control plane network element based on determination method 1 and determination method 2 are different.

[0188] When the first control plane network element determines whether the user plane network element is separated in scenario 2 in the determination method 2, the first control plane network element may determine whether the first information in the node identifier of the SGW-U3 is the same as the second information in the node identifier of the PGW-U2. If the first information in the node identifier of the SGW-U3 is the same as the second information in the node identifier of the PGW-U2, the user plane network element is not separated. If the first information in the node identifier of the SGW-U3 is different from the second information in the node identifier of the PGW-U2, the user plane network element is separated. For example, the node identifier of the SGW-U3 is "DGW3.cityB.provinceA", the first information indicating the area in which the SGW-U3 is located is "cityB.provinceA", the node identifier of the PGW-U2 is "DGW2.cityA.provinceA", and the second information indicating the area in which the PGW-U2 is located is "cityA.provinceA". The first information is different from the second information. In this case, the first control plane network element determines that the user plane network element is isolated.

[0189] When the first control plane network element determines whether the user plane network elements are separated in scenario 1 in the determination method 3, the first control plane network element may determine whether the node identifier of the SGW-U2 and the node identifier of the PGW-U1 are in the same group. If the node identifier of the SGW-U2 and the node identifier of the PGW-U1 are in the same group, the user plane network elements are not separated. If the node identifier of the SGW-U2 and the node identifier of the PGW-U1 are not in the same group, the user plane network elements are separated. The first control plane network element may pre-configure one or more groups. For example, the first control plane network element configures group 1 as {DGW1, DGW2} and group 2 as {DGW3}. The node identifier of the SGW-U2 is "DGW2" and the node identifier of the PGW-U1 is "DGW1". If the first control plane network element determines that the node identifier of the SGW-U2 and the node identifier of the PGW-U1 are in the same group, the first control plane network element determines that the user plane network elements are not separated.

[0190] When the first control plane network element determines whether the user plane network elements are separated in scenario 2 in the determination method 3, the first control plane network element may determine whether the node identifier of the SGW-U3 and the node identifier of the PGW-U2 are in the same group. If the node identifier of the SGW-U3 and the node identifier of the PGW-U2 are in the same group, the user plane network elements are not separated. If the node identifier of the SGW-U3 and the node identifier of the PGW-U2 are not in the same group, the user plane network elements are separated. The first control plane network element may pre-configure one or more groups. For example, the first control plane network element configures group 1 as {DGW1, DGW2} and group 2 as {DGW3}. The node identifier of the SGW-U3 is "DGW3" and the node identifier of the PGW-U2 is "DGW2". If the first control plane network element determines that the node identifier of the SGW-U3 and the node identifier of the PGW-U2 are not in the same group, the first control plane network element determines that the user plane network elements are disjoint.

[0191] In the example shown in Figure 3, the SGW-C and the PGW-C are located in the same control plane network element node. The following uses Figure 4 as an example to describe a communication scenario in which the SGW-C and the PGW-C are located in different control plane network element nodes. It should be noted that the scenario shown in Figure 4 shows a possible deployment case. In practical applications, there may be communication scenarios in which one DGW is connected to multiple CGWs.

[0192] Figure 4 shows two scenarios of the movement process of the terminal device. In scenario 3, the terminal device moves from city B in state A to city C in state A. In scenario 4, the terminal device moves from city C in state A to city D in state B.

[0193] In City B in State A, City C in State A, and City D in State B, both SGW-U and PGW-U are deployed in the same user plane gateway node. In City B in State A, SGW-U2 and PGW-U2 are deployed in DGW2. In City C in State A, SGW-U3 and PGW-U3 are deployed in DGW3. In City C in State B, SGW-U4 and PGW-U4 are deployed in DGW4. PGW-C1 in State A is located in CGW1, and PGW-C1 is connected to PGW-U2; SGW-C2 and PGW-C2 in State A are located in CGW2, and SGW-C2 is connected to SGW-U3, and PGW-C2 is connected to PGW-U3. SGW-C3 and PGW-C3 in State B are located in CGW3, and SGW-C3 is connected to SGW-U4, and PGW-C3 is connected to PGW-U4. Figure 4 shows that MME1 in State A is a CGW 1 and CGW2, and further shows that MME2 in state B is connected to CGW3.

[0194] From Figure 4, we can see that in Scenario 3, when the terminal device moves from City B in State A to City C in State A, MME1 reselects SGW-C based on the location of the terminal device and reselects SGW-C2 from the original SGW-C1. SGW-C2 selects SGW-U3 for the terminal device. Thus, SGW-U is changed from SGW-U2 to SGW-U3. PGW-C1 and PGW-U2 are anchored and remain unchanged. SGW-C2 and PGW-C1 are located in different CGWs.

[0195] The first control plane network element may obtain a node identifier used for comparison by exchanging messages. The first control plane network element may be SGW-C2 or PGW-C1. Messages may be transferred between PGW-C1 and SGW-C2 to exchange node identifiers of user plane network elements. For example, SGW-C2 may send a Modify Bearer Request message to PGW-C1, where the Modify Bearer Request message may carry the node identifier of SGW-U3. PGW-C1 receives the Modify Bearer Request message from SGW-C2 and obtains the node identifier of SGW-U3 from the Modify Bearer Request message. PGW-C1 may send a Modify Bearer Response message to SGW-C2, where the Modify Bearer Response message carries the node identifier of PGW-U2. The SGW-C2 receives the modified bearer response message from the PGW-C1, and the SGW-C2 obtains the node identifier of the PGW-U2 from the modified bearer response message.

[0196] The first control plane network element may determine whether the user plane network element is isolated in scenario 3 using decision methods 1 to 3.

[0197] When the first control plane network element determines whether the user plane network elements are separated in scenario 3 in decision method 1, the first control plane network element may determine whether the node identifier of SGW-U3 is the same as the node identifier of PGW-U2. For example, the node identifier of SGW-U3 is "DGW3" and the node identifier of PGW-U2 is "DGW2". If the first control plane network element determines by comparison that "DGW3" is different from "DGW2" (i.e., DGW3 ≠ DGW2), the first control plane network element considers the user plane network elements to be separated.

[0198] When the first control plane network element determines whether the user plane network element is isolated in scenario 3 in decision method 2, the first control plane network element may determine whether the first information in the node identifier of the SGW-U3 is the same as the second information in the node identifier of the PGW-U2. If the first information in the node identifier of the SGW-U3 is the same as the second information in the node identifier of the PGW-U2, the user plane network element is not isolated. If the first information in the node identifier of the SGW-U3 is different from the second information in the node identifier of the PGW-U2, the user plane network element is isolated. The first information and the second information are information indicating an area. The information indicating an area may be information indicating a state. For example, the node identifier of SGW-U3 is "DGW3.cityC.provinceA", the first information indicating the area in which SGW-U3 is located is "provinceA", the node identifier of PGW-U2 is "DGW2.cityB.provinceA", the second information indicating the area in which PGW-U2 is located is "provinceA". "provinceA" = "provinceA", that is, the first information is the same as the second information. In this case, the first control plane network element determines that the user plane network element is not separated. The information indicating the area may be information indicating a city. For example, the node identifier of SGW-U3 is "DGW3.cityC.provinceA", the first information indicating the area in which SGW-U3 is located is "cityC.provinceA", the node identifier of PGW-U2 is "DGW2.cityB.provinceA", and the second information indicating the area in which PGW-U2 is located is "cityB.provinceA". The first information is different from the second information. In this case, the first control plane network element determines that the user plane network elements are separated.

[0199] When the first control plane network element determines whether the user plane network elements are separated in scenario 3 in the determination method 3, the first control plane network element may determine whether the node identifier of the SGW-U3 and the node identifier of the PGW-U2 are in the same group. If the node identifier of the SGW-U3 and the node identifier of the PGW-U2 are in the same group, the user plane network elements are not separated. If the node identifier of the SGW-U3 and the node identifier of the PGW-U2 are not in the same group, the user plane network elements are separated. The first control plane network element may pre-configure one or more groups. For example, the first control plane network element configures group 1 as {DGW1, DGW2, DGW3} and configures group 2 as {DGW4}. The node identifier of the SGW-U3 is "DGW3" and the node identifier of the PGW-U2 is "DGW2". If the first control plane network element determines that the node identifier of the SGW-U3 and the node identifier of the PGW-U2 are in the same group, the first control plane network element determines that the user plane network elements are not separated.

[0200] As shown in Figure 4, in Scenario 4, when the terminal device moves from City C in State A to City D in State B, MME2 reselects SGW-C based on the location of the terminal device and reselects SGW-C3 from the original SGW-C2. SGW-C3 selects SGW-U4 for the terminal device. Thus, SGW-U is changed from SGW-U3 to SGW-U4. PGW-C2 and PGW-U3 are anchored and remain unchanged. SGW-C3 and PGW-C2 are located in different CGWs.

[0201] The first control plane network element may obtain a node identifier used for comparison by exchanging messages. The first control plane network element may be SGW-C3 or PGW-C2. Messages may be forwarded between PGW-C2 and SGW-C3 to exchange node identifiers of user plane network elements. For example, SGW-C3 may send a Modify Bearer Request message to PGW-C2, where the Modify Bearer Request message may carry the node identifier of SGW-U4. PGW-C2 receives the Modify Bearer Request message from SGW-C3 and obtains the node identifier of SGW-U4 from the Modify Bearer Request message. PGW-C2 may send a Modify Bearer Response message to SGW-C3, where the Modify Bearer Response message carries the node identifier of PGW-U3. The SGW-C3 receives the modified bearer response message from the PGW-C2, and the SGW-C3 obtains the node identifier of the PGW-U3 from the modified bearer response message.

[0202] The first control plane network element may determine whether the user plane network element is isolated in scenario 4 through determination method 1 to determination method 3. The following uses determination method 2 and determination method 3 as examples for explanation.

[0203] When the first control plane network element determines whether the user plane network element is isolated in scenario 4 in decision method 2, the first control plane network element may determine whether the first information in the node identifier of the SGW-U4 is the same as the second information in the node identifier of the PGW-U3. If the first information in the node identifier of the SGW-U4 is the same as the second information in the node identifier of the PGW-U3, the user plane network element is not isolated. If the first information in the node identifier of the SGW-U4 is different from the second information in the node identifier of the PGW-U3, the user plane network element is isolated. The first information and the second information are information indicating an area. The information indicating an area may be information indicating a state. For example, if the SGW-U 4 The node identifier of SGW-U is "DGW4.cityD.provinceB". 4 is located is "provinceB", the node identifier of PGW-U3 is "DGW3.cityC.provinceA", and the second information indicating the area where PGW-U3 is located is "provinceA". "provinceA" ≠ "provinceB", that is, the first information is different from the second information. In this case, the first control plane network element determines that the user plane network element is separated.

[0204] When the first control plane network element determines whether the user plane network elements are separated in scenario 4 in the determination method 3, the first control plane network element may determine whether the node identifier of the SGW-U4 and the node identifier of the PGW-U3 are in the same group. If the node identifier of the SGW-U4 and the node identifier of the PGW-U3 are in the same group, the user plane network elements are not separated. If the node identifier of the SGW-U4 and the node identifier of the PGW-U3 are not in the same group, the user plane network elements are separated. The first control plane network element may pre-configure one or more groups. For example, the first control plane network element configures group 1 as {DGW1, DGW2, DGW3} and configures group 2 as {DGW4}. The node identifier of the SGW-U4 is "DGW4" and the node identifier of the PGW-U3 is "DGW3". If the first control plane network element determines that the node identifier of the SGW-U4 and the node identifier of the PGW-U3 are not in the same group, the first control plane network element determines that the user plane network elements are isolated.

[0205] In summary, an implementation has been described in which a first control plane network element determines whether a user plane network element is isolated based on a first node identifier and a second node identifier. The following describes subsequent operations that may be performed by the first control plane network element if the first control plane network element determines that the user plane network element is isolated.

[0206] In an embodiment, when the first control plane network element determines that the first SGW-U is disassociated from the first PGW-U, the first control plane network element initiates re-establishment of a PDN connection to the terminal device. Optionally, the first control plane network element is an SGW-C. When the SGW-C determines that the first SGW-U is disassociated from the first PGW-U, the SGW-C initiates re-establishment of a PDN connection to the terminal device when the S1 connection to the terminal device is released. In this way, impact on ongoing data and voice services can be avoided. The release of the S1 connection can also be replaced by the terminal device not transmitting data for a certain period of time, or may be replaced by the terminal device entering an idle state. Alternatively, the first control plane network element is a PGW-C. When the PGW-C determines that the first SGW-U is disassociated from the first PGW-U, the PGW-C initiates re-establishment of a PDN connection to the terminal device when the terminal device has no traffic within a specified time. In this way, any impact to ongoing data and voice services can be avoided.

[0207] In a possible design, the first control plane network element may use a timer before initiating the PDN re-establishment. For example, the first control plane network element is an SGW-C. The SGW-C starts the timer when the S1 connection to the terminal device is released. After the timer has elapsed, if the first SGW-U is still detached from the first PGW-U and the terminal device is still in an idle state, the SGW-C initiates the re-establishment of the PDN connection to the terminal device.

[0208] As shown in Figure 5, an example in which the first control plane network element is an SGW-C is used below to describe the procedure in which the first control plane network element triggers a detachment decision with reference to a specific scenario. During the movement of the terminal device, the MME reselects an SGW-C based on the location of the terminal device. The reselected SGW-C is the first control plane network element, and the PGW-C is anchored and unchanged.

[0209] S501: A terminal device sends a tracking area update (TAU) request to a network device, and the network device receives the TAU request.

[0210] S502: The network device sends a TAU request to the MME, and the MME receives the TAU request.

[0211] S503: The MME sends a create session request to the SGW-C, and the SGW-C receives the create session request.

[0212] S504: The SGW-C sends a modify bearer request to the PGW-C, and the PGW-C receives the modify bearer request.

[0213] S505: The PGW-C sends a modify bearer response to the SGW-C, and the SGW-C receives the modify bearer response.

[0214] S506: The SGW-C determines whether the user plane network elements are separated (i.e., whether the SGW-U is separated from the PGW-U), and if the SGW-C determines that the user plane network elements are separated, marks the PDN connection for separation between the SGW-U and the PGW-U.

[0215] The user plane network elements are separate, i.e. the SGW-U and PGW-U activated over a PDN connection are not on the same physical node / user plane network element.

[0216] S507: The SGW-C returns a create session response to the MME, and the MME receives the create session response.

[0217] S508: The MME returns a TAU accept message to the terminal device.

[0218] In this embodiment, for example, it can be understood that the TAU procedure causes SGW reselection. Other procedures (e.g., S1 / X2 handover procedure) may also cause SGW reselection. For procedures performed after other procedures cause SGW reselection, please refer to this embodiment.

[0219] Based on the embodiment of Figure 5, as shown in Figure 6, an example in which the first control plane network element is an SGW-C is used below to describe the procedure in which the first control plane network element starts a timer with reference to a specific scenario. During the movement of the terminal device, the MME reselects the SGW-C based on the location of the terminal device. The reselected SGW-C is the first control plane network element, and the PGW-C is anchored and unchanged. When the S1 connection to the terminal device is released, the SGW-C triggers the re-establishment of a PDN connection for the separation between the SGW-U and the PGW-U.

[0220] S601: The network device sends an S1 user context release request to the MME, and the MME receives the S1 user context release request.

[0221] S602: The MME sends a release access bearer request to the SGW-C, and the SGW-C receives the release access bearer request.

[0222] S603: The SGW-C starts a timer.

[0223] S604: The SGW-C returns a release access bearer response to the MME, and the MME receives the release access bearer response.

[0224] S605: The MME returns an S1 user context release command to the network device, and the network device receives the S1 user context release command.

[0225] S606: The network device sends a radio resource control (RRC) connection release message to the terminal device, and the terminal device receives the RRC connection release message.

[0226] S607: The network device sends an S1 user context release complete message to the MME, and the MME receives the S1 user context release complete message.

[0227] S608: The SGW-C determines that the timer has expired and triggers a PDN re-establishment procedure for the terminal device.

[0228] Based on the embodiment of Figure 5 and / or Figure 6, an example in which the first control plane network element is an SGW-C, as shown in Figure 7, will be used below to describe the procedure in which the first control plane network element initiates PDN re-establishment with reference to a specific scenario. During the movement of the terminal device, the MME reselects an SGW-C based on the location of the terminal device. The reselected SGW-C is the first control plane network element, and the PGW-C is anchored and unchanged.

[0229] S701: The SGW-C sends a delete session request to the PGW-C, and the PGW-C receives the delete session request from the SGW-C.

[0230] S702: The PGW-C sends a delete session response to the SGW-C, and the SGW-C receives the delete session response from the PGW-C.

[0231] S703: The SGW-C sends a delete bearer request to the MME, and the MME receives the delete bearer request.

[0232] The delete bearer request carries one or more of the following information: associated evolved packet system (EPS) bearer identifier and deletion cause. For example, the deletion cause is reactivation requested. The terminal device can be reactivated by carrying the information about the deletion cause. In the activation process, the SGW-C / PGW-C selects a combined SGW-U / PGW-U for the terminal device, so that the user plane network elements can be combined and the path for forwarding data or voice traffic is better.

[0233] S704: The MME initiates paging to the terminal device.

[0234] S705: The MME sends a radio access bearer (E-UTRAN radio access bearer, E-RAB) release command or a deactivate EPS bearer context request to the network device, and the network device receives the E-RAB release command or the deactivate EPS bearer context request.

[0235] S706: The network device sends a radio bearer release request to the terminal device, and the terminal device receives the radio bearer release request.

[0236] S707: The terminal device sends a radio bearer release response to the network device, and the network device receives the radio bearer release response.

[0237] S708: The network device sends an E-RAB release response to the MME, and the MME receives the E-RAB release response.

[0238] S709: The terminal device sends a deactive EPS bearer context accept message to the network device, and the network device receives the deactive EPS bearer context accept message.

[0239] S710: The network device sends a deactivate EPS bearer context accept message to the MME, and the MME receives the deactivate EPS bearer context accept message.

[0240] S711: The MME sends a delete bearer response to the SGW-C, and the SGW-C receives the delete bearer response.

[0241] It can be understood that in Figures 5 to 7, an example in which the first control plane network element is an SGW-C is used to describe the procedure of initiating PDN re-establishment. When the first control plane network element is a PGW-C, the procedure of initiating PDN re-establishment can be obtained by using a similar process. It should be noted that when the first control plane network element is a PGW-C, the PGW-C can trigger the PDN re-establishment procedure of the terminal device after the terminal device has no traffic for a certain time. The PGW-C can send a delete bearer request to the new SGW-C. After receiving the delete bearer request from the PGW-C, the new SGW-C executes steps S703 to S711.

[0242] Based on the same technical concept, the embodiment of the present application further provides a method for determining separation between user plane network elements. As shown in Figure 8, the procedure of the method for determining separation between user plane network elements is as follows: the method is performed by an SGW-C, and the SGW-C and the first PGW-C are located in different control plane network element nodes.

[0243] S801: The SGW-C obtains the address of the first PGW-C.

[0244] S802: The SGW-C determines, based on the address of the first PGW-C and the preset address, whether the SGW-U has disassociated from the first PGW-U or whether to initiate re-establishment of a PDN connection to the terminal device.

[0245] The preset address includes one or more addresses of PGW-C located in the same area as the SGW-C. The address of the PGW-C may be, for example, an S5 / S8 interface IP address. The first PGW-U is a user plane anchor through which the terminal device accesses the PDN, and the first PGW-C is a control plane anchor through which the terminal device accesses the PDN.

[0246] When the SGW-C determines, based on the address of the first PGW-C and the preset address, whether the SGW-U has disassociated from the first PGW-U, the SGW-C may trigger re-establishment of a PDN connection to the terminal device.

[0247] Alternatively, the SGW-C may determine whether to re-establish a PDN connection to the terminal device based on the address of the first PGW-C and the preset address.

[0248] Optionally, if the preset address includes the address of the first PGW-C, the SGW-C determines that the SGW-U has not detached from the first PGW-U or determines that re-establishment of the PDN connection does not need to be initiated.

[0249] If the preset address does not include the address of the first PGW-C, the SGW-C determines that the SGW-U has detached from the first PGW-U or decides to initiate re-establishment of a PDN connection to the terminal device.

[0250] Optionally, the SGW-C may obtain the address of the first PGW-C in the following manner: During the movement of the terminal device, the MME selects a new SGW-C based on the location of the terminal device. According to the 3GPP 29.274 protocol, the MME sends a Create Session Request message to the new SGW-C, and the message carries the S5 / S8 interface address of the first PGW-C anchored by the terminal device. The SGW-C determines whether the SGW-U is disassociated from the first PGW-U based on whether the S5 / S8 interface address of the first PGW-C is within the preset addresses.

[0251] In the embodiment of FIG. 8, the SGW-C determines whether the user plane network elements are isolated based on the address of the control plane network element, and determines that the user plane network elements are isolated when it determines that the control plane network elements are isolated (i.e., the address of the first PGW-C is not in the preset address) by presetting the control plane network element group based on the area. The preset address is the address of the PGW-C in the same area as the SGW-C. In this way, the area can be divided based on the service requirements, and the preset address is set so that the separation between the user plane network elements is more flexibly determined to satisfy the service requirements. The embodiment of FIG. 8 is applicable to a scenario in which the separation between the user plane network elements is determined over a wide area range. In a non-CUPS scenario, the MME determines the separation between the SGW and the PGW based on the canonical node names of the SGW and the PGW. In this solution in which the MME determines the separation between user planes, the gateway node needs to be named in a regular and structured manner, and the UE needs to ensure that the name information of the gateway node is transferred effectively and not lost during 2G / 3G / 4G / 5G interworking. Compared with the above solution in which the MME determines the separation between user planes, in the embodiment of FIG. 8, the separation between user plane network elements can also be determined based on the address of the control plane network element. Note that in the embodiment of FIG. 8, the gateway node does not need to be named in a regular and structured manner, and the UE does not need to ensure that the name information of the gateway node is transferred effectively and not lost during 2G / 3G / 4G / 5G interworking.

[0252] In the embodiment of FIG. 8, in a scenario where the management area of ​​a control plane network element spans between an SGW-U and a PGW-U, it can be determined whether a user plane network element is split. In this scenario, the determination is performed by using the embodiment of FIG. 8, so the decision granularity is large. In solution A, when the SGW-C determines that the control plane network element is split, the SGW-C determines that the user plane network element is split. For example, if the SGW-C determines by comparison that the PGW-C S5 / S8 IP in the create session request message is different from the local PGW-C S5 / S8 IP, the SGW-C determines that the PGW-C and the SGW-C are not in the same control plane network element node. Compared with solution A, in the embodiment of FIG. 8, since the decision granularity is large, the result of the decision of split between user planes can be reduced, and the actions performed after it is determined that the user plane is split, such as PDN re-establishment, can be further reduced to reduce signaling overhead.

[0253] The following describes the embodiment of FIG. 8 in more detail with reference to a specific application scenario.

[0254] Figure 9 shows two scenarios of the movement process of the terminal device. In scenario 5, the terminal device moves from city B in state A to city C. In scenario 6, the terminal device moves from city C in state A to city D in state B. As shown in Figure 9, in cities B and C in state A and city D in state B, SGW-U and PGW-U are both deployed in the same user plane network element node. In city B in state A, SGW-U2 and PGW-U2 are deployed in DGW2. In city C in state A, SGW-U3 and PGW-U3 are deployed in DGW3. In city C in state B, SGW-U4 and PGW-U4 are deployed in DGW4. PGW-C1 in state A is located in CGW1, and PGW-C1 is connected to PGW-U2; SGW-C2 and PGW-C2 in state A are located in CGW2, and SGW-C2 is connected to SGW-U3, and PGW-C2 is connected to PGW-U3. SGW-C3 and PGW-C3 in State B are located in CGW3, SGW-C3 is connected to SGW-U4, and PGW-C3 is connected to PGW-U4. Figure 9 further shows that MME1 in State A is connected to CGW2 and CGW2, and MME2 in State B is connected to CGW3.

[0255] In scenario 5, when the terminal device moves from city B to city C in state A, the MME reselects an SGW-C based on the location of the terminal device and reselects SGW-C2 from the original SGW-C1. SGW-C2 selects SGW-U3 for the terminal device. Thus, SGW-U is changed from SGW-U2 to SGW-U3. PGW-C1 and PGW-U2 are anchored and remain unchanged.

[0256] SGW-C2 may obtain the address of PGW-C1 from the create session request message from the MME. For example, the address of PGW-C1 is S5 / S8 IP “1.1.1.1”. When using solution A to determine whether the user plane network elements are disjoint, SGW-C2 considers that SGW-U is disjoint from PGW-U by default when it determines that the address of PGW-C1 is different from the address of local PGW-C2 S5 / S8 IP “2.2.2.2”. When the solution of the embodiment of FIG. 8 is used, the preset address is configured in SGW-C2, and the preset address includes {1.1.1.1}. If SGW-C2 determines that the address of PGW-C1 is within the preset address, SGW-C2 considers that SGW-U is not disjoint from PGW-U. According to the embodiment of FIG. 8, although the address of PGW-C1 is different from the local PGW-C2 address S5 / S8 IP “2.2.2.2”, if the address of PGW-C1 is within the preset addresses, SGW-C2 still considers that the SGW-U is not detached from the PGW-U.

[0257] In Scenario 6, when the terminal device moves from City C in State A to City D in State B, the MME reselects an SGW-C based on the location of the terminal device, and reselects SGW-C3 from the original SGW-C2, and SGW-C3 selects SGW-U4 for the terminal device. PGW-C2 and PGW-U3 are anchored and remain unchanged.

[0258] The preset addresses {4.4.4.4, 5.5.5.5} are configured in SGW-C3. SGW-C3 obtains the address of PGW-C2, i.e., S5 / S8 IP “2.2.2.2”, from the create session request message sent by the MME. If SGW-C3 determines that the address of PGW-C2 is different from the local PGW-C3 address S5 / S8 IP “3.3.3.3” and that the address of PGW-C2 is not within the preset addresses {4.4.4.4, 5.5.5.5}, ​​SGW-C3 considers that SGW-U is disassociated from PGW-U.

[0259] From the scenario in Figure 9, it can be seen that according to the embodiment of Figure 8, when the terminal device moves within state A, the user plane network elements are usually determined to be not separated. When the terminal device moves between states, the determination of separation between user planes is determined.

[0260] Similar to the technical concept of the embodiment of Fig. 8, the embodiment of the present application further provides a method for determining separation between user plane network elements. As shown in Fig. 10, the procedure of the method for determining separation between user plane network elements is as follows: the method is performed by a PGW-C, and the PGW-C and the first SGW-C are located in different control plane network element nodes.

[0261] S1001: The PGW-C obtains the address of the first SGW-C.

[0262] S1002: The PSGW-C determines whether the PGW-U is disassociated from the first SGW-U or whether to initiate re-establishment of a PDN connection to the terminal device based on the address of the first SGW-C and the preset address. For ease of description, the preset address in the embodiment of FIG. 10 may be referred to as a second preset address.

[0263] The second preset address includes an address of one or more SGW-Cs located in the same area as the PGW-C, and the address of the SGW-C may be, for example, an S5 / S8 interface IP address.

[0264] The PGW-U is a user plane anchor through which a terminal device accesses the PDN, and the PGW-C is a control plane anchor through which a terminal device accesses the PDN.

[0265] When the PGW-C determines, based on the address of the first SGW-C and the preset address, whether the PGW-U has detached from the first SGW-U, the PGW-C may trigger re-establishment of a PDN connection to the terminal device.

[0266] Alternatively, the PGW-C may determine whether to re-establish a PDN connection to the terminal device based on the address of the first SGW-C and the preset address.

[0267] Optionally, if the preset address includes the address of the first SGW-C, the PGW-C determines that the PGW-U has not detached from the first SGW-U or determines that re-establishment of the PDN connection does not need to be initiated.

[0268] If the preset address does not include the address of the first SGW-C, the PGW-C determines that the PGW-U has detached from the first SGW-U or decides to initiate re-establishment of a PDN connection to the terminal device.

[0269] Optionally, the PGW-C may obtain the address of the first SGW-C in the following manner: During the movement of the terminal device, the MME selects a new SGW-C, i.e., the first SGW-C, based on the location of the terminal device, and the first SGW-C sends a modify bearer request message to the PGW-C, where the message carries the S5 / S8 interface address of the new SGW-C. The PGW-C determines whether the PGW-U is detached from the first SGW-U based on whether the S5 / S8 interface address of the first SGW-C is within the preset addresses.

[0270] The embodiment of Fig. 10 and the embodiment of Fig. 8 are based on the same technical concept, but are executed by different entities. Based on the example of the application scenario in the embodiment of Fig. 10, it can be understood that the application scenario shown in the embodiment of Fig. 9 may be referred to, provided that the execution entity is changed from the SGW-C to the PGW-C.

[0271] For the advantageous effects brought by the embodiment of FIG. 10, please refer to the description of the embodiment of FIG. 8. In FIG. 10, the PGW-C determines whether the user plane network element is separated based on the address of the control plane network element, and determines that the user plane network element is separated when it determines that the control plane network element is separated (i.e., the address of the first SGW-C is not in the preset address) by presetting the control plane network element group based on the area. The preset address is the address of the SGW-C in the same area as the PGW-C. In this way, the area can be divided based on the service requirements, and the preset address is set so that the separation between the user plane network elements is more flexibly determined to satisfy the service requirements. Similar to the effect of the embodiment of FIG. 8, in the embodiment of FIG. 10, the gateway nodes do not need to be named in a regular and structured manner, and the decision granularity is large, so that the result of the determination of the separation between the user planes can be reduced, and the operations performed after it is determined that the user plane is separated, such as PDN re-establishment, can be further reduced to reduce the signaling overhead.

[0272] Regarding the method of determining separation between user plane network elements provided in the embodiments of Figures 8 and 10, for the operations performed after it is determined that the user plane network elements are separated, please refer to the operations performed after it is determined that the user plane network elements are separated in the embodiment of Figure 2b. Details will not be described again here. For example, after it is determined that the user plane network elements are separated, re-establishment of a PDN connection to the terminal device is initiated.

[0273] Based on the method for determining isolation between user plane network elements provided in FIG. 2c when this embodiment of the present application is applied to a 5G communication system, the following further describes in detail the method for determining isolation between user plane network elements by using some specific application scenarios.

[0274] As shown in FIG. 11, in a 5G communication system, the procedure of the method for determining separation between user plane network elements is as follows:

[0275] S1101: A terminal device sends a service request to an access network device, and the access network device receives the service request from the terminal device.

[0276] When a terminal device moves within the management area of ​​the SMF, if the terminal device needs to execute a data service, the terminal device initiates a service request procedure.

[0277] S1102: The access network device sends N2 information to the AMF, and the AMF receives the N2 information from the access network device.

[0278] The N2 information carries the service request.

[0279] S1103: AMF sends a PDU session update context request (Nsmf_PDUsession_updateSMcontext request) to SMF, and the SMF receives the PDU session update context request from AMF.

[0280] S1104: The SMF selects the UPF.

[0281] When a terminal device goes out of the coverage area of ​​the PSA-UPF, the SMF determines whether the PSA-UPF (i.e., the PDU session anchor UPF) can serve the area based on the access area of ​​the terminal device. If the PSA-UPF cannot serve the area, the SMF selects an I-UPF for relaying to interact with wireless networks in the area to implement end-to-end network connectivity.

[0282] S1105: The SMF sends an N4 Session Establishment Request to the I-UPF, and the I-UPF receives the N4 Session Establishment Request.

[0283] S1106: The I-UPF returns an N4 session establishment response to the SMF, and the SMF receives the N4 session establishment response.

[0284] S1107: The SMF sends an N4 session modification request to the PSA-UPF, and the PSA-UPF receives the N4 session modification request.

[0285] S1108: The PSA-UPF returns an N4 session modification response to the SMF, and the SMF receives the N4 session modification response.

[0286] S1109: The SMF determines whether the user plane network element is separated.

[0287] If the SMF determines that the user plane network elements are separated, the SMF marks the bearers corresponding to the separation between the user plane network elements.

[0288] The SMF may perform a separation decision based on the node identifier of the I-UPF and the node identifier of the PSA-UPF. For the determination method, please refer to any one of the determination methods 1 to 3. The node identifier of the I-UPF and the node identifier of the PSA-UPF may be, for example, a UPF node identifier (UPF Node ID), or may be other identifiers, for example, a UPF NfInstance ID (3GPP 29.571). The SMF determines whether the user plane is separated, i.e., whether the PSA-UPF is separated from the I-UPF, based on the node identifier of the PSA-UPF and the node identifier of the I-UPF. When determining that the PSA-UPF is separated from the I-UPF, the SMF may trigger a re-establishment of the PDU of the terminal device.

[0289] S1110: The SMF sends a PDU session update context response (Nsmf_PDUsession_updateSMcontext response) to the AMF, and the AMF receives the PDU session update context response.

[0290] S1111: The AMF sends an N2 response (N2 request) to the access network device, and the access network device receives the N2 response and responds thereto.

[0291] S1112: The AMF sends a PDU session update context request (Nsmf_PDUSession_updateSMcontext request) to the SMF, and the SMF receives the PDU session update context request from the AMF.

[0292] S1113: The SMF sends an N4 session modification request to the I-UPF, and the I-UPF receives the N4 session modification request.

[0293] S1114: The I-UPF returns an N4 session modification response to the SMF, and the SMF receives the N4 session modification response.

[0294] S1115: The SMF sends a PDU session update context response (Nsmf_PDUsession_updateSMcontext response) to the AMF, and the AMF receives the PDU session update context response.

[0295] It can be understood that the condition triggering the decision of separation between user plane network elements in the embodiment of Figure 11 is an example. When finding the I-UPF, the SMF decides to separate between user plane network elements. Other conditions may be similar to Xn / N2 handover, causing the insertion of the I-UPF and triggering the SMF to decide to separate between user plane network elements.

[0296] As shown in Figure 12, in a 5G communication system, based on the method for determining isolation between user plane network elements provided in Figure 2c, the procedure of the method for determining isolation between user plane network elements is as follows:

[0297] S1201: A terminal device sends a service request to an access network device, and the access network device receives the service request from the terminal device.

[0298] When a terminal device moves within the management area of ​​the SMF, if the terminal device needs to execute a data service, the terminal device initiates a service request procedure.

[0299] S1202: The access network device sends N2 information to the AMF, and the AMF receives the N2 information from the access network device.

[0300] The N2 information carries the service request.

[0301] S1203: AMF selects SMF.

[0302] When the terminal device goes outside the service area of ​​the SMF, the AMF determines based on the access area of ​​the terminal device that the terminal device has gone outside the management area of ​​the original SMF, and the AMF selects to insert an I-SMF based on the access area of ​​the terminal device.

[0303] S1204: The AMF sends a PDU session create context request (Nsmf_PDUSession_CreateSMContext Request) to the I-SMF, and the I-SMF receives the PDU session create context request from the AMF.

[0304] S1205: I-SMF and SMF transfer PDU session context.

[0305] S1206: I-SMF and I-UPF establish an N4 session.

[0306] The I-SMF selects an I-UPF for relaying. The I-SMF selects an I-UPF in the new area to interwork with wireless networks in the new area.

[0307] S1207: I-SMF sends a PDU session create request (Nsmf_PDUSession_Create Request) message to the SMF.

[0308] The Nsmf_PDUSession_Create Request message may carry a private information element indicating the I-UPF node identifier.

[0309] Alternatively, the Nsmf_PDUSession_Create Request message may carry the N16a interface address of the I-SMF. For example, the N16a interface address of the I-SMF may be carried in the ismfPduSessionUri information element in the PDU Session Create Request message. Alternatively, the Nsmf_PDUSession_Create Request message may carry the node identifier of the I-SMF, for example, ismId. The ismId may be the I-SMF NfInstanceId in the 3GPP 29.502 protocol.

[0310] S1208: The SMF and PSA-UPF execute the N4 session modification procedure.

[0311] S1209: The SMF sends a PDU session create response (Nsmf_PDUSession_Create Response) message to the I-SMF.

[0312] The PDU Session Create Response message sent by the SMF to the I-SMF carries a private information element indicating the node identifier of the PSA-UPF.

[0313] Alternatively, the Nsmf_PDUSession_Create Response message may carry the N16a interface address of the SMF. For example, the N16a interface address of the SMF may be carried in the http message header "Location" in the PDU Session Create Response message. Alternatively, the Nsmf_PDUSession_Create Response message may carry the node identifier of the SMF, for example, smfInstanceId. The smfInstanceId may be the SMF NfInstanceId in the 3GPP 29.502 protocol.

[0314] S1210: The SMF or I-SMF determines separation between user plane network elements.

[0315] For the decision method by which the SMF or I-SMF decides on separation between user plane network elements, please refer to any one of decision methods 1 to 3.

[0316] For example, the SMF or I-SMF may perform separation decision based on the node identifier of the I-UPF and the node identifier of the PSA-UPF. As another example, when separation between user plane gateways is determined in a scenario where a large area range is crossed, the separation between user plane gateways may be determined by separation between control plane gateways. The SMF or I-SMF may determine separation between control plane gateways and further determine separation between user plane gateways based on whether the node identifier of the I-SMF or the node identifier of the SMF is within a pre-set group. Alternatively, the SMF or I-SMF may determine separation between control plane gateways and further determine separation between user plane gateways by determining whether the node identifier of the I-SMF is the same as the node identifier of the SMF by comparison.

[0317] In the 5G protocol, when the I-SMF is inserted and the I-SMF and the SMF exchange the Nsmf_PDUSession_Create Request (ismfId) message and the Nsmf_PDUSession_Create Response (smfInstanceId) message, the I-SMF and the SMF exchange their node identifiers, i.e., ismfId and smfinstanceId. The I-SMF / SMF can determine whether the control plane gateway is separated by comparing the node identifiers, and can also determine whether the user plane gateway is separated without comparing the interface addresses.

[0318] Upon determining that the PSA-UPF is separated from the I-UPF, the SMF or I-SMF may trigger re-establishment of a PDU session of the terminal device.

[0319] S1211: I-SMF sends a PDU session create context response (Nsmf_PDUSession_CreateSMContextResponse) to the AMF, and the AMF receives the PDU session create context response.

[0320] S1212: The AMF sends an N2 response (N2 request) to the access network device, and the access network device receives the N2 response and responds thereto.

[0321] S1213: The AMF sends a PDU session update context request (Nsmf_PDUsession updateSMcontext request) to the I-SMF, and the I-SMF receives the PDU session update context request from the AMF.

[0322] S1214: I-SMF and I-UPF execute the N4 session modification request procedure.

[0323] S1215: I-SMF and SMF perform a PDU session update procedure.

[0324] S1216: I-SMF sends a PDU session update context response (Nsmf_PDUsession updateSMcontext response) to the AMF, and the AMF receives the PDU session update context response.

[0325] It can be understood that in the embodiment of Figure 12, the condition that triggers the decision to separate between user plane network elements is an example. Other conditions may trigger the SMF / I-SMF to decide to separate between user plane network elements, such as an Xn / N2 handover, which causes the insertion of an I-SMF.

[0326] As shown in Figure 13, based on the method of determining separation between user plane network elements provided in Figure 2c, and by using a scenario in which the I-UPF is inserted but the I-SMF is not inserted as an example, the following describes the operations performed after the user plane network elements are separated.

[0327] S1301: A terminal device and an access network device perform an access network connection release ((R)AN Connection Release) procedure.

[0328] S1302: The access network device and the AMF perform an N2 user equipment context release procedure.

[0329] The process may include the access network device sending an N2 User Equipment Context Release Request message to the AMF, the AMF sending an N2 User Equipment Context Release Command message to the access network device, and the access network device sending an N2 User Equipment Context Release Complete message to the AMF.

[0330] S1303: The AMF sends a PDU session update context request to the SMF, and the SMF receives the PDU session update context request.

[0331] S1304: The SMF starts a PDU re-establishment timer.

[0332] S1305: The SMF and PSA-UPF / I-UPF execute the N4 session modification procedure.

[0333] S1306: The SMF returns a PDU session update context response to the AMF.

[0334] S1307: The SMF determines that the PDU re-establishment timer has expired and triggers a PDU session re-establishment procedure of the terminal device.

[0335] S1308: The SMF sends an N4 session release request to the PSA-UPF / I-UPF.

[0336] S1309: PSA-UPF / I-UPF sends an N4 session release response to the SMF.

[0337] S1310: SMF sends communication N1 / N2 message transfer (Namf_Communication_N1N2MessageTransfer) to AMF.

[0338] The N1 SM container includes a PDU Session Release Command, which carries a cause value, which may be Reactivation requested.

[0339] S1311: The AMF and the UE perform a PDU session release procedure.

[0340] S1312: The AMF sends a PDU session update context request to the SMF.

[0341] The PDU session update context request includes an N1 SM container, which carries a PDU session release acknowledgement (ACK) indication.

[0342] S1313: The SMF sends a PDU session update context response to the AMF.

[0343] S1314: The SMF sends a PDU session context status notification (Nsmf_PDUSession_SMContenxtStatusNotify) message to the AMF, and the PDU session context status notification message carries a release instruction, and the AMF receives the PDU session context status notification message and responds to it.

[0344] As shown in Figure 14, based on the method of determining separation between user plane network elements provided in Figure 2c, and by using a scenario in which an I-UPF is inserted and an I-SMF is inserted as an example, the following describes the operations performed after the user plane network elements are separated.

[0345] S1401: A terminal device and an access network device perform an access network connection release procedure.

[0346] S1402: The access network device and the AMF perform an N2 user equipment context release procedure.

[0347] S1403: The AMF sends a PDU session update context request to the I-SMF, and the I-SMF receives the PDU session update context request.

[0348] S1404: The I-SMF starts a PDU re-establishment timer.

[0349] S1405: I-SMF and I-UPF execute the N4 session modification procedure.

[0350] The I-SMF instructs the I-UPF to delete the N3 tunnel information.

[0351] S1406: I-SMF returns a PDU session update context response to AMF.

[0352] S1407: The I-SMF determines that the PDU re-establishment timer has expired and triggers a PDU session re-establishment procedure of the terminal device.

[0353] S1408: I-SMF and I-UPF execute the N4 session modification procedure.

[0354] The I-SMF instructs the I-UPF to stop transferring data.

[0355] S1409: I-SMF sends an N4 session release request (Nsmf_PDUSession_Release Request) to the SMF.

[0356] S1410: The SMF and PSA-UPF perform the N4 session release procedure.

[0357] S1411: The SMF sends an N4 session release response (Nsmf_PDUSession_Release Response) to the I-SMF.

[0358] S1412: I-SMF and I-UPF execute the N4 session release procedure.

[0359] S1413: I-SMF sends communication N1 / N2 message transfer (Namf_Communication_N1N2MessageTransfer) to AMF.

[0360] The N1 SM container includes a PDU Session Release Command, which carries a cause value, which is Reactivation requested.

[0361] S1414: The AMF and the UE perform a PDU session release procedure.

[0362] S1415: The AMF sends a PDU session update context request to the I-SMF.

[0363] The PDU session update context request includes an N1 SM container, which carries a PDU session release acknowledgement (ACK) indication.

[0364] S1416: I-SMF sends a PDU session update context response to AMF.

[0365] S1417: The I-SMF sends a PDU session context status notification (Nsmf_PDUSession_SMContenxtStatusNotify) message to the AMF, and the PDU session context status notification message carries a release instruction, and the AMF receives the notification message and responds to it.

[0366] As shown in Figure 15, based on the method of determining separation between user plane network elements provided in Figure 2c, and by using the scenario in which an I-SMF is inserted as an example, the following describes the operations performed after the user plane network elements are separated.

[0367] S1501: The SMF initiates re-establishment of a PDU session of a terminal device when it determines that the terminal device has no traffic within a specified time.

[0368] S1502: The SMF and PSA-UPF execute the N4 session modification procedure.

[0369] S1503: The SMF sends a PDU session update request (Nsmf_PDUSession_Update Request) to the I-SMF.

[0370] S1504: I-SMF and I-UPF execute the N4 session release procedure.

[0371] S1505: I-SMF sends communication N1 / N2 message transfer (Namf_Communication_N1N2MessageTransfer) to AMF.

[0372] The N1 SM container includes a PDU Session Release Command, which carries a cause value, which is Reactivation requested.

[0373] S1506: The AMF and the UE perform a PDU session release procedure.

[0374] S1507: The AMF sends a PDU session update context request to the I-SMF.

[0375] The PDU session update context request includes an N1 SM container, which carries a PDU session release acknowledgement (ACK) indication.

[0376] S1508: I-SMF sends a PDU session update context response to AMF.

[0377] S1509: I-SMF sends a PDU session update response to the SMF.

[0378] S1510: The SMF and PSA-UPF execute the N4 session release procedure.

[0379] S1511: The SMF sends a PDU session status notify (Nsmf_PDUSession_StatusNotify) message to the I-SMF, and the PDU session status notify message carries a release instruction.

[0380] S1512: The I-SMF sends a PDU session context status notification (Nsmf_PDUSession_SMContextStatusNotify) message to the AMF, and the PDU session context status notification carries a release instruction.

[0381] The following further describes in detail how to determine separation between user plane network elements in a scenario where a large area range is crossed in a 5G communication system.

[0382] As shown in FIG. 16, the procedure of the method for determining isolation between user plane network elements is as follows: the method is performed by the I-SMF.

[0383] S1601: The I-SMF obtains the address of the first SMF.

[0384] S1602: The I-SMF determines, based on the address of the first SMF and the preset address, whether the I-UPF has separated from the first PSA-UPF or whether to initiate re-establishment of a PDU session of the terminal device.

[0385] The preset addresses include addresses of one or more SMFs located in the same area as the I-SMF, where the first PSA-UPF is a user plane anchor for the terminal device and the first SMF is a control plane anchor for the terminal device.

[0386] If the I-SMF determines, based on the address of the first SMF and the preset address, that the I-UPF has separated from the first PSA-UPF, the I-SMF may trigger re-establishment of a PDU session of the terminal device.

[0387] Alternatively, the I-SMF may determine whether to re-establish a PDU session of the terminal device based on the address of the first SMF and the preset address.

[0388] Optionally, if the preset address includes the address of the first SMF, the I-SMF determines that the I-UPF has not separated from the first PSA-UPF or determines that re-establishment of the PDU session does not need to be initiated.

[0389] If the preset address does not include the address of the first SMF, the I-SMF determines that the I-UPF has separated from the first PSA-UPF or decides to initiate re-establishment of a PDU session of the terminal device.

[0390] In the embodiment of FIG. 16, in a scenario where the management area of ​​the control plane network element spans between the I-UPF and the PSA-UPF, it can be determined whether the user plane network element is split. In this scenario, the determination is performed by using the embodiment of FIG. 16, so the decision granularity is large. In solution B, when the I-SMF determines that the control plane network element is split, the I-SMF determines that the user plane network element is split. For example, the I-SMF compares the address of the SMF with the address of the local SMF. If the I-SMF determines that the address of the SMF is different from the address of the local SMF, the I-SMF considers the user plane network element to be split as well, since it determines that the SMF and the I-SMF are not in the same control plane network element node. Compared to solution B, in the embodiment of FIG. 16, since the decision granularity is large, the result of the decision of split between the user planes can be reduced, and the action performed after it is determined that the user plane is split, such as PDU session re-establishment, can be further reduced to reduce signaling overhead.

[0391] Similar to the technical concept of the embodiment of Figure 16, the embodiment of the present application further provides a method for determining separation between user plane network elements. As shown in Figure 17, the procedure of the method for determining separation between user plane network elements is as follows: the method is performed by an SMF, and the SMF and the first I-SMF are located in different control plane network element nodes.

[0392] S1701: The SMF obtains the address of the first I-SMF.

[0393] S1702: The SMF determines whether the PSA-UPF is dissociated from the first I-UPF or whether to initiate re-establishment of a PDU session of a terminal device based on the address of the first I-SMF and the preset address. For ease of description, the preset address in the embodiment of FIG. 17 may be referred to as a third preset address.

[0394] The third preset address includes the address of one or more I-SMFs located within the same area as the SMF.

[0395] The PSA-UPF is the user plane anchor of the terminal device, and the SMF address is the control plane anchor of the terminal device.

[0396] If the SMF determines, based on the address of the first I-SMF and the preset address, that the PSA-UPF has separated from the first I-UPF, the SMF may trigger re-establishment of a PDU session of the terminal device.

[0397] Alternatively, the SMF may determine whether to re-establish a PDU session for the terminal device based on the address of the first I-SMF and a preset address.

[0398] Optionally, if the preset address includes the address of the first I-SMF, the SMF determines that the PSA-UPF has not separated from the first I-UPF or that re-establishment of the PDU session does not need to be initiated.

[0399] If the preset address does not include the address of the first I-SMF, the SMF determines that the PSA-UPF has separated from the first I-UPF or decides to initiate re-establishment of a PDU session of the terminal device.

[0400] For advantageous effects provided by the embodiment of FIG. 17, please refer to the description of the embodiment of FIG.

[0401] It can be understood that to implement the functions in the foregoing embodiments, the first control plane network element, SGW-C, or PGW-C includes corresponding hardware structures and / or software modules for performing each function. Those skilled in the art should easily realize that the present application can be implemented by using hardware or a combination of hardware and computer software by combining the units and method steps in the examples described in the embodiments disclosed in the present application. Whether the functions are implemented by using hardware or hardware driven by computer software depends on the specific application scenario and design constraints of the technical solution.

[0402] 18 and 19 are schematic diagrams of possible structures of communication devices according to the embodiments of the present application, respectively. The communication device may be configured to implement the functions of the first control plane network element, SGW-C, PGW-C, I-SMF, or SMF in the above-mentioned method embodiments, so that the advantageous effects of the above-mentioned method embodiments can also be implemented. In this embodiment of the present application, the communication device may be the SGW-C shown in FIG. 1a, or may be the PGW-C shown in FIG. 1a. The communication device may be a module (e.g., a chip) applied to the SGW-C or PGW-C. The communication device may be the SMF shown in FIG. 1b. The communication device may be a module (e.g., a chip) applied to the SMF.

[0403] As shown in Figure 18, the communication device 1800 includes an obtaining unit 1810 and a determining unit 1820. The communication device 1800 is configured to perform functions of a first control plane network element in the embodiment of the method shown in Figure 2a, Figure 2b, or Figure 2c, or to perform functions of an SGW-C in the embodiment of the method shown in Figure 8, or to perform functions of a PGW-C in the embodiment of the method shown in Figure 10, or to perform functions of an I-SMF in the embodiment of the method shown in Figure 16, or to perform functions of an SMF in the embodiment of the method shown in Figure 17.

[0404] When the communication device 1800 is configured to perform the function of a first control plane network element in the embodiment of the method shown in FIG. 2a, the obtaining unit 1810 is configured to obtain a first node identifier of the first user plane network element and a second node identifier of the second user plane network element, and the device includes a serving gateway for control plane SGW-C, a data network PDN gateway for control plane PGW-C, a session management function SMF, or an intermediate session management function I-SMF, and the first user plane network element is a user plane anchor; The determining unit 1820 is configured to determine, based on the first node identifier and the second node identifier, whether the first user plane network element is disjoint from the second user plane network element.

[0405] Optionally, when obtaining the first node identifier of the first user plane network element, the obtaining unit 1810 is configured to obtain the first node identifier of the first user plane network element from a second control plane network element, where the device is an SGW-C and the first user plane network element is a data network PDN gateway for a first user plane PGW-U, or the device is a PGW-C and the first user plane network element is a serving gateway for a first user plane SGW-U, or the device is an SMF and the first user plane network element is an intermediate user plane management function I-UPF, or the device is an I-SMF and the first user plane network element is a protocol data unit session anchor user plane management function PSA-UPF.

[0406] Optionally, when determining whether the first user plane network element is detached from the second user plane network element based on the first node identifier and the second node identifier, the determining unit 1820 is configured to: determine that the first user plane network element is not detached from the second user plane network element if the first node identifier is the same as the second node identifier, or determine that the first user plane network element is detached from the second user plane network element if the first node identifier is different from the second node identifier.

[0407] Optionally, when determining whether the first user plane network element is disjoint from the second user plane network element based on the first node identifier and the second node identifier, the determining unit 1820 is configured to: determine that the first user plane network element is not disjoint from the second user plane network element if the first information in the first node identifier is the same as the second information in the second node identifier; or determine that the first user plane network element is disjoint from the second user plane network element if the first information in the first node identifier is different from the second information in the second node identifier, where the first information indicates an area in which the first user plane network element is located and the second information indicates an area in which the second user plane network element is located.

[0408] Optionally, when determining whether the first user plane network element is disassociated from the second user plane network element based on the first node identifier and the second node identifier, the determining unit 1820 is configured to: determine that the first user plane network element is not disassociated from the second user plane network element if the first node identifier and the second node identifier are in the same group, or determine that the first user plane network element is disassociated from the second user plane network element if the first node identifier and the second node identifier are not in the same group.

[0409] Optionally, the communication apparatus 1800 further includes a re-establishment unit 1830 configured to initiate re-establishment of a data transmission path of the terminal device when the determination unit determines that the first user plane network element is separated from the second user plane network element.

[0410] Optionally, the communication apparatus 1800 is an SGW-C. When initiating re-establishment of a data transmission path of the terminal device, the re-establishment unit 1830 is configured to initiate re-establishment of a packet data network PDN connection to the terminal device when the S1 connection to the terminal device is released.

[0411] Optionally, the communication apparatus 1800 is an I-SMF. When initiating re-establishment of the data transmission path of the terminal device, the re-establishment unit 1830 is configured to initiate re-establishment of a protocol data unit PDU session of the terminal device when the N1 / N2 connection to the terminal device is released.

[0412] Optionally, the communication device 1800 is a PGW-C or an SMF. When initiating re-establishment of a data transmission path of a terminal device, the re-establishment unit 1830 is configured to initiate re-establishment of a data transmission path of the terminal device when the terminal device has no traffic within a specified time.

[0413] When the communications device 1800 is configured to perform the functions of a first control plane network element in the embodiment of the method shown in FIG. 2b, the obtaining unit 1810 is configured to obtain a first node identifier of a first user plane data network PDN gateway PGW-U and a second node identifier of a first user plane serving gateway SGW-U, and the determining unit 1820 is configured to determine whether the first SGW-U has detached from the first PGW-U based on the first node identifier and the second node identifier.

[0414] Optionally, the first control plane network element is an SGW-C. When acquiring a first node identifier of the first PGW-U, the acquiring unit 1810 is configured to acquire a first node identifier of the first PGW-U from a PGW-C, where the PGW-C is a control plane anchor for the terminal device to access the PDN.

[0415] Optionally, the first control plane network element is a PGW-C, and the PGW-C is a control plane anchor for a terminal device to access a PDN. When acquiring a second node identifier of the first SGW-U, the acquiring unit 1810 is configured to acquire a second node identifier of the first SGW-U from the SGW-C.

[0416] Optionally, when determining whether the first SGW-U has detached from the first PGW-U based on the first node identifier and the second node identifier, the determining unit 1820 is configured to determine that the first SGW-U has not detached from the first PGW-U if the first node identifier is the same as the second node identifier, or to determine that the first SGW-U has detached from the first PGW-U if the first node identifier is different from the second node identifier.

[0417] Optionally, when determining whether the first SGW-U is detached from the first PGW-U based on the first node identifier and the second node identifier, the determining unit 1820 is configured to determine that the first SGW-U is not detached from the first PGW-U if the first information in the first node identifier is the same as the second information in the second node identifier, or to determine that the first SGW-U is detached from the first PGW-U if the first information in the first node identifier is different from the second information in the second node identifier, where the first information indicates an area in which the first SGW-U is located and the second information indicates an area in which the first PGW-U is located.

[0418] Optionally, when determining whether the first SGW-U has detached from the first PGW-U based on the first node identifier and the second node identifier, the determining unit 1820 is configured to determine that the first SGW-U has not detached from the first PGW-U if the first node identifier and the second node identifier are in the same group, or to determine that the first SGW-U has detached from the first PGW-U if the first node identifier and the second node identifier are not in the same group, and the SGW-U and PGW-U in the group are located in the same area.

[0419] Optionally, the apparatus 1800 further includes a re-establishment unit 1830 configured to initiate re-establishment of a PDN connection to the terminal device when the determining unit 1820 determines that the first SGW-U is detached from the first PGW-U.

[0420] In a possible design, the first control plane network element is an SGW-C. When initiating re-establishment of a PDN connection to the terminal device, the re-establishment unit is configured to initiate re-establishment of a PDN connection to the terminal device when the S1 connection to the terminal device is released.

[0421] In a possible design, the first control plane network element is a PGW-C. When initiating re-establishment of a PDN connection to the terminal device, the re-establishment unit is configured to initiate re-establishment of the PDN connection of the terminal device when the terminal device has no traffic within a specified time.

[0422] When the communication apparatus 1800 is configured to implement the functions of the SGW-C in the embodiment of the method shown in FIG. 8, the obtaining unit 1810 is configured to obtain an address of a first PGW-C, and the determining unit 1820 is configured to determine, based on the address of the first PGW-C and the preset address, whether the serving gateway for user plane SGW-U has disassociated from the first PGW-U, or the determining unit 1820 is configured to determine, based on the address of the first PGW-C and the preset address, whether a PDN connection of the terminal device should be re-established, where the preset address includes addresses of one or more PGW-C located in the same area as the SGW-C, the first PGW-U is a user plane anchor for the terminal device to access the PDN, and the first PGW-C is a control plane anchor for the terminal device to access the PDN.

[0423] Optionally, when determining whether the serving gateway for user plane SGW-U has detached from the first PGW-U based on the address of the first PGW-C and the preset address, the determining unit 1820 is specifically configured to determine, for the SGW-C, that the SGW-U has not detached from the first PGW-U if the preset address includes the address of the first PGW-C, or to determine, for the SGW-C, that the SGW-U has detached from the first PGW-U if the preset address does not include the address of the first PGW-C.

[0424] Optionally, the apparatus 1800 further includes a re-establishing unit 1830 configured to initiate re-establishment of a PDN connection to the terminal device when the determining unit 1820 determines that the SGW-U is detached from the first PGW-U.

[0425] Optionally, the re-establishment unit 1830 is further configured to initiate re-establishment of a PDN connection to the terminal device when the S1 connection to the terminal device is released.

[0426] Optionally, the re-establishment unit 1830 may be further configured to start a timer when the S1 connection to the terminal device is released, and initiate re-establishment of a PDN connection to the terminal device after the timer has elapsed.

[0427] When the communications apparatus 1800 is configured to perform the functions of a PGW-C in the embodiment of the method shown in FIG. 10 , the obtaining unit 1810 is configured to obtain an address of a first SGW-C, and the determining unit 1820 is configured to determine whether the PGW-U is disjoint from a first serving gateway for user plane SGW-U based on the address of the first SGW-C and the preset address, where the preset address includes addresses of one or more SGW-C located in the same area as the PGW-C, the PGW-U is a user plane anchor for terminal devices to access the PDN, and the PGW-C is a control plane anchor for terminal devices to access the PDN.

[0428] Optionally, when determining whether the PGW-U has detached from the first user plane serving gateway SGW-U based on the address of the first SGW-C and the preset address, the determining unit 1820 is specifically configured to determine, for the PGW-C, that the PGW-U has not detached from the first SGW-U if the preset address includes the address of the first SGW-C, or to determine, for the PGW-C, that the PGW-U has detached from the first SGW-U if the preset address does not include the address of the first SGW-C.

[0429] Optionally, the apparatus 1800 further includes a re-establishing unit 1830, configured to initiate re-establishment of a PDN connection to the terminal device when the determining unit determines that the PGW-U is detached from the first SGW-U.

[0430] Optionally, the re-establishment unit 1830 may be further configured to initiate re-establishment of a PDN connection to the terminal device when the terminal device has no traffic within a specified time.

[0431] Optionally, the re-establishment unit 1830 may be further configured to start a timer if the terminal device has no traffic within a specified time, and initiate re-establishment of a PDN connection to the terminal device after the timer has elapsed.

[0432] When the communication device 1800 is configured to implement the functions of the I-SMF in the embodiment of the method shown in FIG. 16, the obtaining unit 1810 is configured to obtain an address of a first SMF, and the determining unit 1820 is configured to determine whether the I-UPF has dissociated from the first PSA-UPF or whether to initiate re-establishment of a PDU session of the terminal device based on the address of the first SMF and a preset address, where the preset address includes addresses of one or more SMFs located in the same area as the I-SMF, the first PSA-UPF is a user plane anchor of the terminal device, and the first SMF is a control plane anchor of the terminal device.

[0433] In a possible design, the communication apparatus 1800 further includes a re-establishment unit 1830. The re-establishment unit 1830 is configured to trigger re-establishment of a PDU session of the terminal device when the determination unit determines, based on the address of the first SMF and the preset address, that the I-UPF is separated from the first PSA-UPF.

[0434] In a possible design, when determining whether the I-UPF is separated from the first PSA-UPF based on the address of the first SMF and the preset address, the determination unit 1820 is specifically configured to determine that, for the I-SMF, the I-UPF is not separated from the first PSA-UPF if the preset address includes the address of the first SMF, or to determine that, for the I-SMF, the I-UPF is separated from the first PSA-UPF if the preset address does not include the address of the first SMF.

[0435] When the determining unit determines, based on the address of the first SMF and the preset address, that the I-UPF is dissociated from the first PSA-UPF, the re-establishing unit may trigger re-establishment of the PDU session of the terminal device, optionally, the re-establishing unit 1830 may be configured to initiate re-establishment of the PDU session of the terminal device when the N1 / N2 connection to the terminal device is released. Further, optionally, the re-establishing unit 1830 may be further configured to start a timer when the N1 / N2 connection to the terminal device is released, and initiate re-establishment of the PDU session of the terminal device after the timer has elapsed.

[0436] When the communication device 1800 is configured to implement the functions of the SMF in the embodiment of the method shown in FIG. 17, the obtaining unit 1810 is configured to obtain an address of a first I-SMF, and the determining unit 1820 is configured to determine whether the PSA-UPF has dissociated from the first I-UPF or whether to initiate re-establishment of a PDU session of the terminal device based on the address of the first I-SMF and the preset address, where the preset address includes addresses of one or more I-SMFs located in the same area as the SMF, and the PSA-UPF may be a user plane anchor of the terminal device, and the SMF may be a control plane anchor of the terminal device.

[0437] In a possible design, when determining whether the PSA-UPF is separated from the 1I-UPF based on the address of the 1I-SMF and the preset address, the determination unit 1820 is specifically configured to determine that the PSA-UPF is not separated from the 1I-UPF if the preset address includes the address of the 1I-SMF, or to determine that, for an SMF, the PSA-UPF is separated from the 1I-UPF if the preset address does not include the address of the 1I-SMF.

[0438] In a possible design, the communication apparatus 1800 further includes a re-establishment unit 1830 configured to initiate re-establishment of a PDU session of the terminal device when the determination unit determines that the PSA-UPF is separated from the first I-UPF.

[0439] Based on when the determination unit determines that the PSA-UPF is separated from the first I-UPF, the re-establishment unit initiates re-establishment of a PDU session of the terminal device. Optionally, the re-establishment unit 1830 may be further configured to initiate re-establishment of a PDU session of the terminal device when the terminal device has no traffic within a specified time.

[0440] For further detailed description of the acquisition unit 1810, the determination unit 1820, and the re-establishment unit 1830, please directly refer to the relevant description in the above method embodiment. Details will not be described again here. The acquisition unit 1810, the determination unit 1820, and the re-establishment unit 1830 may also perform steps in other method embodiments.

[0441] As shown in FIG. 19, the communication device 1900 includes a processor 1910 and may optionally further include an interface circuit 1920. The processor 1910 and the interface circuit 1920 are coupled to each other. The interface circuit 1920 may be a transceiver or an input / output interface. Optionally, the communication device 1900 may further include a memory 1930 configured to store instructions to be executed by the processor 1910, or to store input data required for the processor 1910 to execute the instructions, or to store data generated after the processor 1910 executes the instructions.

[0442] When the communication device 1900 is configured to perform the method shown in Figure 2a, Figure 2b, Figure 2c, Figure 8, Figure 10, Figure 16 or Figure 17, the processor 1910 may be configured to perform the functions of the acquisition unit 1810, the determination unit 1820, and / or the re-establishment unit 1830, and the interface circuit 1920 may be configured to perform some of the functions of the acquisition unit 1810.

[0443] When the communication device is a chip applied to a first control plane network element, the chip of the first control plane network element implements the function of the first control plane network element in the above method embodiment.

[0444] When the communication device is a chip applied in a PGW-C or an SGW-C, the chip in the PGW-C or SGW-C implements the functions of the PGW-C or SGW-C in the above method embodiments.

[0445] When the communication device is a chip applied to I-SMF or SMF, the I-SMF or SMF chip implements the functions of I-SMF or SMF in the above method embodiments.

[0446] The processor in this embodiment of the present application may be a Central Processing Unit (CPU) or other general-purpose processor, a Digital Signal Processor (DSP), an Application-Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The general-purpose processor may be a microprocessor, any conventional processor, etc.

[0447] In the present embodiment, the memory may be a non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), or a volatile memory, such as a random access memory (RAM). The memory may be any other medium that can carry or store expected program code in the form of instructions or data structures and is accessible by a computer, but is not limited thereto. The memory in the present embodiment may alternatively be a circuit or any other device that can implement a storage function and is configured to store program instructions and / or data.

[0448] Some or all of the operations and functions performed by the first control plane network element, the PGW-C, the SGW-C, the I-SMF, or the SMF described in the above method embodiments of the present application may be implemented by using chips or integrated circuits.

[0449] An embodiment of the present application further provides a chip including a processor configured to support a communications device to perform the functions of the first control plane network element, the PGW-C, the SGW-C, the I-SMF, or the SMF in the embodiments of the method described above. In a possible design, the chip is connected to or includes a memory, the memory being configured to store program instructions and data required by the communications device.

[0450] An embodiment of the present application provides a computer-readable storage medium storing a computer program, the computer program including instructions used to execute the embodiments of the method described above.

[0451] An embodiment of the present application provides a computer program product including instructions, which, when executed on a computer, perform the aforementioned method embodiments.

[0452] Those skilled in the art should understand that the embodiments of the present application may be provided as a method, a system, or a computer program product. Thus, the present application may take the form of a hardware-only embodiment, a software-only embodiment, or an embodiment that combines software and hardware. Furthermore, the present application may take the form of a computer program product embodied in one or more computer usable storage media (including, but not limited to, disk memory, CD-ROM, optical memory, etc.) that contain program code usable by a computer.

[0453] The present application is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present application. It should be understood that computer program instructions can be used to implement each process and / or each block in the flowcharts and / or block diagrams, and combinations of processes and / or blocks in the flowcharts and / or block diagrams. These computer program instructions may be provided to a processor of a general purpose computer, a special purpose computer, an embedded processor, or other programmable data processing device to generate a machine, whereby the instructions executed by the processor of the computer or other programmable data processing device generate an apparatus for implementing the specific functions of one or more processes in the flowcharts and / or one or more blocks in the block diagrams.

[0454] These computer program instructions may alternatively be stored in a computer-readable memory that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable memory cause an artifact to be generated that includes an instruction apparatus that implements a specific function in one or more processes in the flowcharts and / or one or more blocks in the block diagrams.

[0455] These computer program instructions may alternatively be loaded onto a computer or other programmable data processing device such that a sequence of operations and steps are executed on the computer or other programmable data processing device, thereby generating a computer-implemented process. Thus, the instructions executed on the computer or other programmable data processing device provide steps to implement a specific function in one or more processes in the flowcharts and / or one or more blocks in the block diagrams.

[0456] Although several embodiments of the present application have been described, those skilled in the art can change and modify these embodiments by knowing the basic inventive concept. Therefore, the following claims are intended to be interpreted as covering the embodiments and all changes and modifications within the scope of the present application.

[0457] It is apparent that those skilled in the art can make various modifications and variations to the embodiments of the present application without departing from the scope of the embodiments of the present application. This application is intended to cover those modifications and variations, provided that they fall within the scope of protection claimed by the following claims and their equivalent technologies.

[0458] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to Chinese Patent Application No. 202111356850.1, filed with the State Intellectual Property Office of the People's Republic of China on November 16, 2021, for the invention titled "METHOD FOR DETERMINING SEPARATION BETWEEN USER PLANE NETWORK ELEMENTS AND COMMUNICATION APPARATUS," which is incorporated herein by reference in its entirety.

Claims

1. A method for determining separation between user plane network elements between which a terminal device traverses, wherein one of the user plane network elements functions as a user plane anchor, comprising: acquiring, by a first control plane network element, a first node identifier of a first user plane network element and a second node identifier of a second user plane network element, the first control plane network element having a serving gateway for a control plane, a data network gateway for a control plane, a session management function, or an intermediate session management function; determining, by the first control plane network element, whether the first user plane network element is disjoint from the second user plane network element based on the first node identifier and the second node identifier; The method according to claim 1,

2. Obtaining a first node identifier of a first user plane network element by the first control plane network element comprises obtaining, by the first control plane network element, the first node identifier of the first user plane network element from a second control plane network element; the first control plane network element is a serving gateway for the control plane, the second control plane network element is a data network gateway for the control plane, and the first user plane network element is a data network gateway for the first user plane; or the first control plane network element is a data network gateway for the control plane, the second control plane network element is a serving gateway for the control plane, and the first user plane network element is a serving gateway for the first user plane; or the first control plane network element is the session management function, the second control plane network element is the intermediate session management function, and the first user plane network element is an intermediate user plane management function; or the first control plane network element is the intermediate session management function, the second control plane network element is the session management function, and the first user plane network element is a protocol data unit session anchor user plane management function; The method of claim 1.

3. determining, by the first control plane network element, whether the first user plane network element is disassociated from the second user plane network element based on the first node identifier and the second node identifier, determining that the first user plane network element is not disjointed from the second user plane network element if the first node identifier is the same as the second node identifier, or determining that the first user plane network element is disjointed from the second user plane network element if the first node identifier is different from the second node identifier. The method of claim 1.

4. determining, by the first control plane network element, whether the first user plane network element is disassociated from the second user plane network element based on the first node identifier and the second node identifier, determining that the first user plane network element is not disjointed from the second user plane network element if first information in the first node identifier is the same as second information in the second node identifier, or determining that the first user plane network element is disjointed from the second user plane network element if first information in the first node identifier differs from second information in the second node identifier; The first information indicates an area in which the first user plane network element is located, and the second information indicates an area in which the second user plane network element is located. The method of claim 1.

5. determining, by the first control plane network element, whether the first user plane network element is disassociated from the second user plane network element based on the first node identifier and the second node identifier, determining that the first user plane network element is not disjoint from the second user plane network element if the first node identifier and the second node identifier are in the same group, or determining that the first user plane network element is disjoint from the second user plane network element if the first node identifier and the second node identifier are not in the same group. The method of claim 1.

6. The method comprises: and initiating, by the first control plane network element, a re-establishment of a data transmission path of the terminal device when the first control plane network element determines that the first user plane network element is isolated from the second user plane network element. The method of claim 1.

7. the first control plane network element is a serving gateway for the control plane; Initiating re-establishment of a data transmission path of the terminal device includes initiating re-establishment of a packet data network (PDN) connection to the terminal device by the control plane serving gateway when an S1 connection to the terminal device is released. The method according to claim 6.

8. the first control plane network element is the intermediate session management function; Initiating re-establishment of the data transmission path of the terminal device includes initiating re-establishment of a protocol data unit (PDU) session of the terminal device when an N1 / N2 connection to the terminal device is released by the intermediate session management function. The method according to claim 6.

9. the first control plane network element is the control plane data network gateway or the session management function; Initiating re-establishment of the data transmission path of the terminal device includes initiating re-establishment of the data transmission path of the terminal device by the control plane data network gateway or the session management function when the terminal device has no traffic within a specified time. The method according to claim 6.

10. An apparatus for determining separation between user plane network elements over which a terminal device traverses, wherein one of the user plane network elements functions as a user plane anchor, comprising: An acquisition unit configured to acquire a first node identifier of a first user plane network element and a second node identifier of a second user plane network element, the acquisition unit having a serving gateway for a control plane, a data network gateway for a control plane, a session management function, or an intermediate session management function; a determining unit configured to determine whether the first user plane network element is disjoint from the second user plane network element based on the first node identifier and the second node identifier; An apparatus having the above configuration.

11. When acquiring the first node identifier of the first user plane network element, the acquiring unit is configured to acquire the first node identifier of the first user plane network element from a second control plane network element; the device is a serving gateway for the control plane, the second control plane network element is a data network gateway for the control plane, and the first user plane network element is a data network gateway for the first user plane; or the device is a data network gateway for the control plane, the second control plane network element is a serving gateway for the control plane, and the first user plane network element is a serving gateway for the first user plane; or the device is the session management function, the second control plane network element is the intermediate session management function, and the first user plane network element is an intermediate user plane management function; or the device is the intermediate session management function, the second control plane network element is the session management function, and the first user plane network element is a protocol data unit session anchor user plane management function; 11. The apparatus of claim 10.

12. When determining whether the first user plane network element is disjoint from the second user plane network element based on the first node identifier and the second node identifier, the determining unit: determining that the first user plane network element is not disjointed from the second user plane network element if the first node identifier is the same as the second node identifier, or determining that the first user plane network element is disjointed from the second user plane network element if the first node identifier is different from the second node identifier.

11. The apparatus of claim 10.

13. When determining whether the first user plane network element is disjoint from the second user plane network element based on the first node identifier and the second node identifier, the determining unit: determining that the first user plane network element is not disjointed from the second user plane network element if first information in the first node identifier is the same as second information in the second node identifier, or determining that the first user plane network element is disjointed from the second user plane network element if the first information in the first node identifier is different from the second information in the second node identifier; The first information indicates an area in which the first user plane network element is located, and the second information indicates an area in which the second user plane network element is located.

11. The apparatus of claim 10.

14. When determining whether the first user plane network element is disjoint from the second user plane network element based on the first node identifier and the second node identifier, the determining unit: determining that the first user plane network element is not disjointed from the second user plane network element if the first node identifier and the second node identifier are in the same group, or determining that the first user plane network element is disjointed from the second user plane network element if the first node identifier and the second node identifier are not in the same group.

11. The apparatus of claim 10.

15. The apparatus comprises: a re-establishment unit configured to initiate a re-establishment of a data transmission path of the terminal device when the determining unit determines that the first user plane network element is separated from the second user plane network element.

11. The apparatus of claim 10.

16. the device is a serving gateway for the control plane; When initiating re-establishment of the data transmission path of the terminal device, the re-establishment unit is configured to initiate re-establishment of a packet data network (PDN) connection to the terminal device when an S1 connection to the terminal device is released.

16. The apparatus of claim 15.

17. the apparatus being the intermediate session management function; When initiating re-establishment of the data transmission path of the terminal device, the re-establishment unit is configured to initiate re-establishment of a protocol data unit (PDU) session of the terminal device when an N1 / N2 connection to the terminal device is released; 16. The apparatus of claim 15.

18. the device is the control plane data network gateway or the session management function; When initiating re-establishment of the data transmission path of the terminal device, the re-establishment unit is configured to initiate re-establishment of the data transmission path of the terminal device when the terminal device has no traffic within a specified time.

16. The apparatus of claim 15.

19. 1. A method for determining isolation between user plane network elements, comprising: obtaining, by a control plane serving gateway, an address of a first control plane data network gateway; determining, by the control plane serving gateway, whether a user plane serving gateway is separated from a first user plane data network gateway based on the address of the first control plane data network gateway and a preset address, the preset address including addresses of one or more control plane data network gateways located in the same area as the control plane serving gateway, the first user plane data network gateway being a user plane anchor for a terminal device to access a PDN, and the first control plane data network gateway being a control plane anchor for the terminal device to access the PDN; The method according to claim 1,

20. determining, by the control plane serving gateway, whether a user plane serving gateway is disassociated from a first user plane data network gateway based on the address and a preset address of the first control plane data network gateway; determining, by the control plane serving gateway, that the user plane serving gateway is not disjoint from the first user plane data network gateway if the preset address has the address of the first control plane data network gateway, or determining, by the control plane serving gateway, that the user plane serving gateway is disjoint from the first user plane data network gateway if the preset address does not have the address of the first control plane data network gateway.

20. The method of claim 19.

21. The method comprises: and initiating, by the control plane serving gateway, a re-establishment of a PDN connection to the terminal device when the control plane serving gateway determines that the user plane serving gateway is disassociated from the first user plane data network gateway.

20. The method of claim 19.

22. Initiating re-establishment of a PDN connection to the terminal device includes initiating re-establishment of the PDN connection to the terminal device by the control plane serving gateway when an S1 connection to the terminal device is released.

22. The method of claim 21.

23. 1. A method for determining isolation between user plane network elements, comprising: obtaining, by the intermediate session management function, an address of the first session management function; determining, by the intermediate session management function, whether the intermediate user plane management function is separate from a first protocol data unit session anchor user plane management function based on the address of the first session management function and a preset address, the preset address including addresses of one or more session management functions located in the same area as the intermediate session management function, the first protocol data unit session anchor user plane management function being a user plane anchor of a terminal device, and the first session management function being a control plane anchor of the terminal device; The method according to claim 1,

24. determining, by the intermediate session management function, based on the address of the first session management function and a preset address, whether an intermediate user plane management function is disassociated from a first protocol data unit session anchor user plane management function; determining, by the intermediate session management function, if the preset address comprises the address of the first session management function, that the intermediate user plane management function is not disjoint from the first protocol data unit session anchor user plane management function, or, if the preset address does not comprise the address of the first session management function, determining, by the intermediate session management function, that the intermediate user plane management function is disjoint from the first protocol data unit session anchor user plane management function.

24. The method of claim 23.

25. If the intermediate session management function determines that the intermediate user plane management function is dissociated from the first protocol data unit session anchor user plane management function, the method further comprises: and initiating, by the intermediate session management function, a re-establishment of a PDN connection of the terminal device.

24. The method of claim 23.

26. 1. A method for determining isolation between user plane network elements, comprising: obtaining, by a session management function, an address of a first intermediate session management function; determining, by the session management function, whether a protocol data unit session anchor user plane management function is disjoint from a first intermediate user plane management function based on the address of the first intermediate session management function and a preset address, the preset address including addresses of one or more intermediate session management functions located in the same area as the session management function, the protocol data unit session anchor user plane management function being a user plane anchor of a terminal device, and the session management function being a control plane anchor of the terminal device; The method according to claim 1,

27. determining, by the session management function, whether a protocol data unit session anchor user plane management function is dissociated from a first intermediate user plane management function based on the address of the first intermediate session management function and a preset address; determining by the session management function that the protocol data unit session anchor user plane management function is not disjoint from the first intermediate user plane management function if the preset address has the address of the first intermediate session management function, or determining by the session management function that the protocol data unit session anchor user plane management function is disjoint from the first intermediate user plane management function if the preset address does not have the address of the first intermediate session management function.

27. The method of claim 26.

28. If the session management function determines that the protocol data unit session anchor user plane management function is disjoint from the first intermediate user plane management function, the method further comprises: and initiating, by the session management function, a re-establishment of a PDN connection of the terminal device.

27. The method of claim 26.

29. An apparatus for determining isolation between user plane network elements, comprising: Apparatus comprising a unit arranged to carry out a method according to any one of claims 19 to 22, or a method according to any one of claims 23 to 25, or a method according to any one of claims 26 to 28.

30. storing computer programs or instructions; When the computer program or the instructions are executed by a communication device, the method according to any one of claims 1 to 9, or the method according to any one of claims 19 to 22, or the method according to any one of claims 23 to 25, or the method according to any one of claims 26 to 28 is performed. A computer-readable storage medium.

31. a first control plane network element, a first user plane network element, and a second user plane network element; - the first control plane network element is configured to perform a method according to any one of claims 1 to 9, or a method according to any one of claims 19 to 22, or a method according to any one of claims 23 to 25, or a method according to any one of claims 26 to 28 Communication systems.

32. at least one processor; The processor is configured to perform a method according to any one of claims 1 to 9, or a method according to any one of claims 19 to 22, or a method according to any one of claims 23 to 25, or a method according to any one of claims 26 to 28. Tips.

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