UP function device, method executed by the UP function device, and program

Abstract

To enable UP control using a plurality of UP functions while reducing the load on a CP function. [Solution] The UP function device includes a receiving unit that receives a Packet Forwarding Control Protocol (PFCP) message, a selection unit that selects a User Plane (UP) function device to which the PFCP message is to be forwarded, and a forwarding unit that forwards the PFCP message to the UP function device selected by the selection unit.

Description

[Technical Field]

[0001] The present disclosure relates to a User Plane (UP) function device, a method executed by the UP function device, and a program. [Background technology]

[0002] In recent years, with the diversification of services offered, the packet control functions of User(U)-Plane have increased. Furthermore, with the standardization of the loosely coupled architecture of Evolved Packet Core (EPC) Control and User Plane Separation (CUPS) and 5th Generation Core network (5GC), and the adoption of multi-vendor solutions by carriers, third-party UP functions are emerging in addition to those from traditional mobile core vendors. As a result, combining multiple UP functions rather than implementing services with a single UP function is becoming the de facto standard.

[0003] As a related technology, Patent Document 1 discloses control and user plane management for inter-device communication within a LAN, such as a 5G Local Area Network (LAN). In Patent Document 1, multiple user devices can be serviced by different User Plane Functions (UPFs). In this case, the Session Management Function (SMF) configures two or more UPFs using Packet Forwarding Control Protocol (PFCP) signaling so that those UPFs can forward traffic from one UE to the other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-109789 Summary of the Invention [Problem to be solved by the invention]

[0005] U-Plane control, along with session information, is centrally managed by the Control Plane (CP) function. However, the number of UP functions managed has increased dramatically due to network slicing, Multi-access Edge Computing (MEC), and scaling, making centralized management by a single CP function complex and a significant burden from the perspective of maintenance and operation. In addition, some third-party UP functions do not terminate General Packet Radio Service (GPRS) Tunneling Protocol for User Plane (GTP-U) tunnels, but instead only perform packet control using session information. For this reason, managing U-Plane control by the CP function is not necessarily best practice.

[0006] When multiple UP functions are required for a single session, the 3rd Generation Partnership Project (3GPP) standard for EPC CUPS requires the deployment of a Serving Gateway (SGW) User plane function (SGW-U), Packet Data Network Gateway (PGW) User plane function (PGW-U), and Traffic Detection Function (TDF) User plane function (TDF-U) with their corresponding SGW Control plane function (SGW-C), PGW Control plane function (PGW-C), and TDF Control plane function (TDF-C), respectively, and their one-to-one connection. However, some TDF products do not include TDF-C. In addition, some operators may not be able to deploy TDF-C due to their own circumstances. In such cases, it is common to implement proprietary integrations that carbon copy or snoop Remote Authentication Dial-In User Service (RADIUS) protocol messages from U-Plane traffic, which are not intended for authentication or billing purposes. This method has the problem that the reliability of the procedure itself is low and policy control according to the session cannot be performed.

[0007] On the other hand, in 5GC, in accordance with the 3GPP standard, it is possible for a CP function to send Packet Forwarding Control Protocol (PFCP) messages to multiple UP functions. However, centralized management of multiple UP functions by a CP function impacts call processing performance due to the increase in the number of UP functions and the complexity of selection rules, and imposes a heavy burden from the viewpoint of maintenance and operation.

[0008] One exemplary object of this disclosure is to provide a UP function device, a method executed by the UP function device, and a program that enable UP control using multiple UP functions while reducing the burden on the CP function. [Means for solving the problem]

[0009] A UP function device according to a first aspect of this disclosure includes a receiving unit that receives Packet Forwarding Control Protocol (PFCP) messages, a selection unit that selects a User Plane (UP) function device to which the PFCP messages are to be forwarded, and a forwarding unit that forwards the PFCP messages to the UP function device selected by the selection unit.

[0010] A method performed in a UP function device according to a second aspect of the present disclosure includes receiving a Packet Forwarding Control Protocol (PFCP) message, selecting a UP function device to which the PFCP message is to be forwarded, and forwarding the PFCP message to the selected UP function device.

[0011] A program relating to a third aspect of this disclosure causes a processor to perform a process that includes receiving a Packet Forwarding Control Protocol (PFCP) message, selecting a User Plane (UP) function device to which the PFCP message is to be forwarded, and forwarding the PFCP message to the selected UP function device. [Effects of the Invention]

[0012] The UP function device, the method executed by the UP function device, and the program relating to this disclosure enable UP control using multiple UP functions. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram showing a schematic configuration of a network to which a UP function device according to the present disclosure is applied; [Figure 2] FIG. 2 is a block diagram illustrating a configuration example of a UPF. [Figure 3] This is a sequence diagram showing an example of network operation when a Packet Data Unit (PDU) session is established in 5GC. [Figure 4] A sequence diagram showing another example of network operation when establishing a PDU session in 5GC. [Figure 5] FIG. 2 is a block diagram illustrating an example of a hardware configuration of a UPF. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described in detail. In the following description and drawings, for clarity of explanation, appropriate omissions and simplifications have been made. In addition, in each drawing, the same or similar elements are designated by the same reference numerals, and duplicate explanations have been omitted as necessary.

[0015] Figure 1 is a block diagram illustrating the schematic configuration of a network to which the UP function device according to this disclosure is applied. In one embodiment, the network 100 includes a Radio Access Network (RAN) 101, an Access and Mobility Management Function (AMF) 102, a Session Management Function (SMF) 103, User Plane Functions (UPF) 104A-C, and a Data Network (DN) 105. In this embodiment, the network 100 is assumed to be a 5G core network.

[0016] RAN101 is a radio access network. DN105 is a data network external to 5GC, such as the Internet. AMF102 performs subscriber authentication, security, and terminal location management. AMF102 is connected to RAN101 via N2. SMF103 performs session management. UPF104A to 104C each perform packet forwarding of user data. AMF102 and SMF103 correspond to the CP function in 5GC. UPF104A to 104C correspond to the UP function in 5GC. In the following description, UPF104A to 104C will also be referred to as UPF104 when there is no need to particularly distinguish between them.

[0017] The SMF 103 transmits a PFCP message in the 5G PDU Session Establishment Procedure. The PFCP message includes, for example, an N4 Session Establishment / Modification Request. The UPF 104A receives the PFCP message from the SMF 103 via the N4 interface. The UPF 104A establishes a GTP-U tunnel in the PDU Session Establishment Procedure. This GTP-U tunnel is terminated at the UPF 104A, which receives the PFCP message directly from the SMF 103.

[0018] The UPF 104A forwards the PFCP message received from the SMF 103 to the UPF 104B via the N4 interface. In the example of FIG. 1, the UPF 104B further forwards the PFCP message forwarded from the UPF 104A to the UPF 104C via the N9 interface. In FIG. 1, the UPF 104A is the UPF that forwards the PFCP message. The UPF 104B is the UPF that forwards the PFCP message to and is also the UPF that forwards the PFCP message. The UPFs 104A to 104C forward user data packets between the RAN 101 and the DN 105.

[0019] 2 is a block diagram showing an example configuration of the UPF 104. The UPF 104 includes a receiving unit 141, a selecting unit 142, and a transferring unit 143. The UPF 104 may be physically configured as a device including, for example, one or more processors and one or more memories. In the UPF 104, at least some of the functions of each unit within the UPF 104 may be realized by the one or more processors executing processes in accordance with programs read from the one or more memories.

[0020] The receiver 141 receives a message to be transferred from the SMF 103 or another UPF 104. In this embodiment, the message to be transferred is a PFCP Session related message described in 3GPP TS 29.244 V18.1.0 Table 7.3-1 Message Types. The receiver 141 receives the PFCP message to be transferred, for example, in a session establishment procedure.

[0021] The selection unit 142 selects the UPF 104 to which the PFCP message is to be transferred. The selection of the UPF 104 by the selection unit 142 complies with, for example, 3GPP TS 23.214 v17.0.0(2021-06) 5.12 User Plane Function Selection and 3GPP TS 23.501 v18.1.0(2023-03) 6.3.3 User Plane Function Selection.

[0022] The forwarding unit 143 forwards the PFCP message received by the receiving unit 141 to the UP function device selected by the selecting unit 142 via the N9 interface. The forwarding unit 143, for example, forwards the PFCP message as is to another UPF 104. Alternatively, the forwarding unit 143 may add predetermined attribute information such as Attribute Value Pairs (AVP) to the PFCP message and forward the PFCP message with the added attribute information to another UPF 104. The forwarding unit 143 may replace at least a part of the parameters included in the PFCP message with other parameters and forward the PFCP message with the replaced parameters to another UPF 104.

[0023] The transfer unit 143 transfers the PFCP message to the UPF 104 selected by the selector 142 using at least one of serial transfer, parallel transfer, and broadcast transfer. Here, serial transfer is a transfer method in which a UPF 104 that receives a PFCP message Request from an SMF 103 transfers the Request to another UPF 104 before returning a Response to the SMF 103. In serial transfer, the Request is transferred to the terminating UPF 104, and then a Response to the Request is transferred by looping back along the Request transfer path. In contrast, parallel transfer is a transfer method in which a UPF 104 that receives a PFCP message Request from an SMF 103 returns a Response to the SMF 103, and then forwards the Request to another UPF 104. In parallel transfer, a UPF that receives the forwarded Request returns a Response to the UPF 104 that transferred the Request, and then forwards the Request to another UPF 104. Broadcast forwarding is a forwarding method in which a UPF104 that receives a PFCP message Request from an SMF103 forwards the Request to all UPF104s that can communicate with it. When a PFCP message is forwarded between multiple UPF104s, the forwarding method used for the PFCP message may be determined individually by each UPF104.

[0024] 3 is a sequence diagram showing an example of the operation of the network 100 when a Packet Data Unit (PDU) session is established in 5GC. In the 5G PDU Session Establishment Procedure, the SMF 103 transmits an N4 Session Establishment / Modification Request, which is a PFCP message, to the UPF 104A (step A1). The receiver 141 of the UPF 104A receives the PFCP message from the SMF 103. The UPF 104A establishes a GTP-U tunnel between the RAN 101 and the UPF 104A. The receiver 141 transmits an N4 Session Establishment / Modification Response, which is a response to the received PFCP message, to the SMF 103 (step A2).

[0025] The selection unit 142 of the UPF 104A selects a UPF to which the N4 Session Establishment / Modification Request is to be forwarded (step A3). Here, it is assumed that the UPF 104B is selected as the UPF to which the N4 Session Establishment / Modification Request is to be forwarded. The forwarding unit 143 of the UPF 104A determines whether to forward the PFCP message to the UPF 104B transparently, i.e., forward it as is, add an AVP to the PFCP message, or forward the PFCP message after performing parameter substitution (step A4). For example, when different U-Plane controls, such as bandwidth control (communication speed limit), billing control (communication volume accumulation), or communication data compression, are implemented for each of the associated UP function devices, the UPF 104A adds an AVP or substitutes parameters. The forwarding unit 143 forwards the N4 Session Establishment / Modification Request to the UPF 104B (step A5).

[0026] The receiving unit 141 of UPF104B receives an N4 Session Establishment / Modification Request from UPF104A. The selection unit 142 of UPF104B selects the UPF to which the N4 Session Establishment / Modification Request will be forwarded (step A6). Here, it is assumed that UPF104C is selected as the UPF to which the request will be forwarded. The forwarding unit 143 of UPF104B decides whether to forward the PFCP message transparently to UPF104C, to forward the PFCP message with AVP added, or to forward the PFCP message after parameter substitution (step A7). The forwarding unit 143 forwards the N4 Session Establishment / Modification Request to UPF104C (step A8).

[0027] The receiver 141 of UPF104C receives an N4 Session Establishment / Modification Request from UPF104B. UPF104C sends an N4 Session Establishment / Modification Response to UPF104B, which is a response to the PFCP message forwarded from UPF104B in step A8 (step A9). UPF104B sends an N4 Session Establishment / Modification Response to UPF104A, which is a response to the PFCP message forwarded from UPF104A in step A5 (step A10).

[0028] The SMF 103 establishes a PFCP association with the UPF 104A. The UPF 104A establishes a PFCP association with the UPF 104B. The UPF 104B establishes a PFCP association with the UPF 104C. The implementation of PFCP Heartbeat (alive monitoring) between the SMF 103 and the UPFs 104A to 104C is optional. The GTP-U tunnel established between the RAN 101 and the UPF 104A is terminated at the UPF 104A, and the UPFs 104B and 104C, to which the PFCP messages are forwarded, are outside the GTP tunnel.

[0029] 4 is a sequence diagram showing another example of the operation of the network 100 when a PDU session is established in 5GC. In the 5G PDU Session Establishment Procedure, the SMF 103 transmits an N4 Session Establishment / Modification Request to the UPF 104A (step B1). The receiver 141 of the UPF 104A receives a PFCP message from the SMF 103. The UPF 104A establishes a GTP-U tunnel between the RAN 101 and the UPF 104A. The receiver 141 transmits an N4 Session Establishment / Modification Response to the SMF 103 (step B2). Steps B1 and B2 may be similar to steps A1 and A2 shown in FIG. 3.

[0030] The selection unit 142 of UPF104A selects the UPF to which the N4 Session Establishment / Modification Request will be forwarded (step B3). Here, it is assumed that UPF104B is selected as the UPF to which the forwarding will be forwarded. The forwarding unit 143 of UPF104A decides whether to forward the PFCP message transparently to UPF104B, to forward the PFCP message with AVP added, or to forward the PFCP message after parameter substitution (step B4). The forwarding unit 143 forwards the N4 Session Establishment / Modification Request to UPF104B (step B5).

[0031] The receiver 141 of UPF104B receives an N4 Session Establishment / Modification Request from UPF104A. UPF104B sends an N4 Session Establishment / Modification Response to UPF104A, which is a response to the PFCP message forwarded from UPF104A in step B5 (step B6).

[0032] Furthermore, the selection unit 142 of UPF104A selects the UPF to which the N4 Session Establishment / Modification Request will be forwarded (step B7). Here, it is assumed that UPF104C is selected as the UPF to which the request will be forwarded. The forwarding unit 143 of UPF104A decides whether to forward the PFCP message transparently to UPF104C, to forward the PFCP message with AVP added, or to forward the PFCP message after parameter substitution (step B8). The forwarding unit 143 forwards the N4 Session Establishment / Modification Request to UPF104C (step B9).

[0033] The receiving unit 141 of the UPF 104C receives the N4 Session Establishment / Modification Request from the UPF 104A. The UPF 104C transmits to the UPF 104A an N4 Session Establishment / Modification Response, which is a response to the PFCP message forwarded from the UPF 104A in step B9 (step B10). In this example, as in the example shown in Fig. 3, the SMF 103 can establish a PFCP association between the UPFs 104A to 104C to which the PFCP message is transmitted or forwarded.

[0034] In this embodiment, when a session is established in 5GC, UPF 104 receives a PFCP message from SMF 103, which is a CP function, and forwards the PFCP message to another UPF 104 based on a preset selection rule. By UPF 104 forwarding the PFCP message received from SMF 103 to another UPF 104, SMF 103 can perform U-Plane session control using multiple UPFs 104. In this embodiment, PFCP messages are exchanged directly between two or more UPFs 104, which reduces the load on SMF 103 and improves reliability. In this embodiment, if parameters of the PFCP message are replaced during forwarding, policy control according to the session can be realized in network 100 using the parameters set in the PFCP message.

[0035] The above embodiment can be applied to a 5G standalone (SA) Mobile Virtual Network Operator (MVNO) business model, which is currently being considered and adjusted. In this case, it becomes possible to realize services with a higher degree of freedom for MVNO operators while reducing the maintenance and operation burden on Mobile Network Operators (MNOs). Specifically, when the UPF of an MNO operator and the UPF of an MVNO operator are connected via an N9 interface, a new function-opening model, U-Plane as a Service (UaaS), can be realized. Alternatively, when the SMF of an MNO operator and the UPF of an MVNO operator are connected via an N4 interface, a new function-opening model, UaaS, can be realized.

[0036] In the above description, an example has been described in which a PFCP message is transferred between UPFs 104 in the 5G PDU Session Establishment Procedure, but the present embodiment is not limited to this. For example, a UPF 104 may transfer a PFCP message to another UPF 104 in another procedure for exchanging PFCP messages, such as a Handover Procedure.

[0037] Furthermore, in the above description, an example has been described in which the network 100 is a 5GC, but the present embodiment is not limited to this. The network 100 may be an EPC CUPS. In this case, the UP function may forward a PFCP message to another UP function in a procedure for exchanging PFCP messages in the EPC CUPS. In the present disclosure, the UP function includes a PGW-U, an SGW-U, a combined SGW / PGW-U, and a UPF. The CP function includes a PGW-C, an SGW-C, a combined SGW / PGW-C, and an SMF.

[0038] Next, a hardware configuration of the UPF 104 will be described. Fig. 5 is a block diagram showing an example of the hardware configuration of the UPF 104. The UPF 104 has a processor 501 such as a central processing unit (CPU), a read only memory (ROM) 502, and a random access memory (RAM) 503. In the UPF 104, the processor 501, the ROM 502, and the RAM 503 are connected to each other via a bus 504. Although not shown, the UPF 104 may include other circuits such as peripheral circuits, communication circuits, and interface circuits.

[0039] The ROM 502 is a non-volatile storage device. For example, a semiconductor storage device with a relatively small capacity, such as a flash memory, is used for the ROM 502. The ROM 502 stores the programs executed by the processor 501.

[0040] The program includes instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include RAM, ROM, flash memory, solid-state drive (SSD) or other memory technologies, compact discs (CDs), digital versatile discs (DVDs), Blu-ray discs or other optical disc storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices. The program may also be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0041] RAM503 is a volatile memory device. Various semiconductor memory devices, such as Dynamic Random Access Memory (DRAM) or Static Random Access Memory (SRAM), can be used for RAM503. RAM503 can be used as an internal buffer for temporarily storing data.

[0042] The processor 501 loads the program stored in the ROM 502 into the RAM 503 and executes the program. The CPU 501's execution of the program enables the functionality of each component within the UPF 104.

[0043] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0044] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0045] For example, some or all of the above embodiments may also be described as follows, but are not limited to the following.

[0046] [Appendix 1] a receiver for receiving a Packet Forwarding Control Protocol (PFCP) message; a selection unit for selecting a User Plane (UP) function device to which the PFCP message is to be transferred; a transfer unit that transfers the PFCP message to the UP function device selected by the selection unit.

[0047] [Appendix 2] The UP function device according to Supplementary Note 1, wherein the receiving unit receives the PFCP message from a Control Plane (CP) function.

[0048] [Appendix 3] The UP function device of Appendix 2, wherein the CP function includes a Packet Data Network Gateway (PGW) Control plane function (PGW-C), a Serving Gateway (SGW) Control plane function (SGW-C), a Combined SGW / PGW-C, and a Session Management Function (SMF).

[0049] [Appendix 4] The UP function device is a UP function device described in any one of appendixes 1 to 3, including a Packet Data Network Gateway (PGW) User plane function (PGW-U), a Serving Gateway (SGW) User plane function (SGW-U), a Combined SGW / PGW-U, and a User plane function (UPF).

[0050] [Appendix 5] A UP function device according to any one of Supplementary Notes 1 to 4, wherein the receiving unit receives the PFCP message from another UP function device.

[0051] [Appendix 6] An UP function device described in any one of Supplementary Notes 1 to 5, wherein the forwarding unit forwards the PFCP message as is to the UP function device selected by the selection unit, forwards the PFCP message with specified attribute information added to the UP function device selected by the selection unit, or forwards the PFCP message with some of the parameters included in the PFCP message changed to the UP function device selected by the selection unit.

[0052] [Appendix 7] The transfer unit transfers the PFCP message to the UP function device selected by the selection unit using at least one of serial transfer, parallel transfer, and broadcast transfer, as described in any one of Appendix 1 to 6.

[0053] [Appendix 8] A UP function device according to any one of Supplementary Notes 1 to 7, wherein the receiving unit receives the PFCP message in a session establishment procedure.

[0054] [Appendix 9] 1. A method performed by a User Plane (UP) function device, comprising: Receives Packet Forwarding Control Protocol (PFCP) messages, Selecting a UP function device to which the PFCP message is to be transferred; forwarding the PFCP message to the selected UP function device.

[0055] [Appendix 10] Receives Packet Forwarding Control Protocol (PFCP) messages, Select a User Plane (UP) function device to which the PFCP message is to be transferred; a program causing a processor to execute processing including transferring the PFCP message to the selected UP function device;

[0056] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 8 that are dependent on Supplementary Note 1 may also be dependent on Supplementary Notes 9 and 10 in the same dependency relationship as Supplementary Notes 2 to 8. Some or all of the elements described in any Supplementary Note may be applied to various hardware, software, recording means for recording software, systems, and methods. [Explanation of symbols]

[0057] 100: Network 101:RAN 102:AMF 103: SMF 104:UPF 105:DN 141: Receiving Unit 142: Selection Section 143: Transfer section

Claims

1. a receiver for receiving a Packet Forwarding Control Protocol (PFCP) message; a selection unit that selects a User Plane (UP) function device to which the PFCP message is to be transferred; a transfer unit that transfers the PFCP message to the UP function device selected by the selection unit.

2. The UP function device according to claim 1 , wherein the receiving unit receives the PFCP message from a Control Plane (CP) function.

3. The UP function device according to claim 2, wherein the CP functions include a Packet Data Network Gateway (PGW) Control plane function (PGW-C), a Serving Gateway (SGW) Control plane function (SGW-C), a Combined SGW / PGW-C, and a Session Management Function (SMF).

4. The UP function device according to any one of claims 1 to 3, wherein the UP function device includes a Packet Data Network Gateway (PGW) User plane function (PGW-U), a Serving Gateway (SGW) User plane function (SGW-U), a Combined SGW / PGW-U, and a User plane function (UPF).

5. The UP function device according to claim 1 , wherein the receiving unit receives the PFCP message from another UP function device.

6. 4. A UP function device as described in any one of claims 1 to 3, wherein the transfer unit transfers the PFCP message as is to the UP function device selected by the selection unit, transfers the PFCP message with specified attribute information added to the UP function device selected by the selection unit, or transfers the PFCP message with some of the parameters included in the PFCP message changed to the UP function device selected by the selection unit.

7. 4. A UP function device according to claim 1, wherein the transfer unit transfers the PFCP message to the UP function device selected by the selection unit using at least one of serial transfer, parallel transfer, and broadcast transfer.

8. The UP function device according to claim 1 , wherein the receiving unit receives the PFCP message in a session establishment procedure.

9. 1. A method performed by a User Plane (UP) function device, comprising: receiving a Packet Forwarding Control Protocol (PFCP) message; Selecting a UP function device to which the PFCP message is to be transferred; forwarding the PFCP message to the selected UP function device.

10. receiving a Packet Forwarding Control Protocol (PFCP) message; Select a User Plane (UP) function device to which the PFCP message is to be transferred; A program causing a processor to execute a process including transferring the PFCP message to the selected UP function device.

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