Communication system, router, program, and communication management method

Abstract

Provided is a communication system wherein: a first router has a table storage unit that stores a table indicating the correspondence between an IP prefix of a subordinate network and an SRv6 SID of a Locator + Function length less than an IP prefix length corresponding to the IP prefix; a second router has an SID generation unit that generates an SID including a portion of the address of a destination located under the first router and header information, and a packet transmission unit that transmits an SRv6 packet including the SID to the first router; and the first router also has a packet generation unit that, when the SRv6 packet is received from the second router, identifies an IP prefix corresponding to the SID included in the SRv6 packet with reference to the correspondence table, identifies the address of the destination using the IP prefix and the portion of the address of the destination included in the SID, and generates a packet using the identified address and the header information.

Description

Communication system, router, program, and communication management method

[0001] The present invention relates to a communication system, a router, a program, and a communication management method.

[0002] Patent Document 1 describes a forwarding device that performs forwarding processing using protocols such as SRv6 (Segment Routing IPv6) and SR-MPLS (Multi-Protocol Label Switching). [Prior art documents] [Patent documents] [Patent document 1] JP 2020-174231 A General disclosure

[0003] According to one embodiment of the present invention, there is provided a communication system. The communication system may include a first router and a second router. The first router may have a table storage unit that stores a correspondence table between IP prefixes of a network under the first router and SRv6 SIDs with a Locator+Function length shorter than the IP prefix length corresponding to the IP prefix. The second router may have a SID generation unit that generates an SID that includes a portion of an address of a destination under the first router and header information of a packet to be sent to the destination. The second router may have a packet transmission unit that transmits an SRv6 packet including the SID generated by the SID generation unit to the first router. The first router may have a packet generation unit that, when receiving the SRv6 packet from the second router, refers to the correspondence table to identify an IP prefix corresponding to the SID included in the SRv6 packet, identifies the address of the destination using the identified IP prefix and a part of the address of the destination included in the SID, and generates a packet to be sent to the destination using the identified address and the header information included in the SID.

[0004] In the communication system, the first router may be a PE router that converts SRv6-compliant SRv6 packets into GTP-U-compliant GTP-U packets, the table storage unit may store the correspondence table between the IP prefix of the RAN under the first router and the SRv6 SID, the second router may have a route information receiving unit that receives UE route information including the gNB address of the gNB to which the UE is connected, advertised by the controller, the SID generation unit may generate the SID including a portion of the gNB address and the header information, and the packet generation unit may identify the gNB address using an IP prefix corresponding to the SID included in the SRv6 packet and a portion of the gNB address included in the SID, and may generate a GTP-U packet to be sent to the gNB using the identified gNB address and the header information. The SID generation unit generates the SID including a portion of the gNB address and the header information including the TEID, QFI, and RQI included in the UE route information, and the packet generation unit may generate the GTP-U packet using the specified gNB address and the TEID, QFI, and RQI included in the header information. The packet generation unit may generate the GTP-U packet with the specified gNB address as a destination address and with the TEID, QFI, and RQI included in the header information set.The first router may have an advertisement unit that advertises an Interwork Segment Discovery (ISD) route, and the ISD route may indicate GTP6.E.Reduced as SID Behavior in a BGP attribute that stores an SRv6 SID, and when a prefix length of an IP prefix of an actual RAN that includes an IP prefix corresponding to the SID is shorter than an Arg. Mob. Session length compared to a SID Locator / Function length, the second router may add, to an NLRI, the Locator / Function length of the SID and the Arg. Mob. Session length including a stuff area for the second router to embed the Arg. Mob. Session in the SID. The SID generation unit may store an IP prefix having the same length as a length of an SRv6 SID NLRI, and when the gNB address included in the UE route information is included in the IP prefix stored in the NLRI of the ISD route received from the first router including the stuff area, and when Behavior of the SRv6 SID indicates GTP6.E.Reduced, the SID generation unit may generate the SID by storing an Arg. Mob. Session consisting of the header information including the TEID, the QFI, and the RQI included in the UE route information in an Argument area within the SID, and storing the value of the gNB address in the same bit position as the remaining bits in the remaining Argument bits, and the packet generation unit may generate the SID by storing an Arg. Mob. Session consisting of the header information including the TEID, the QFI, and the RQI included in the UE route information in an Argument area within the SID, and storing the value of the gNB address in the same bit position as the remaining bits in the remaining Argument bits, and When an SRv6 packet having a Reduced SID as the active SID is received, the Arg. Mob. Session is obtained from the SID, and the gNB address is identified from the IP prefix including the stuff area and the value of the gNB address at the same bit position as the remaining bit, and the TEID, the QFI, and the RQI may be obtained from the Arg. Mob. Session.The first router may include a table management unit that deletes a pair of SRv6 SIDs corresponding to the RAN IP prefix from the correspondence table when a route having a destination prefix including a RAN IP prefix having a stuff area for embedding Arg. Mob. Session from a VRF connected to the gNB is lost or reachability to the IP prefix is ​​lost, and the advertising unit may perform a withdrawal route advertisement for an ISD route having the RAN IP prefix in its NLRI when the pair of SRv6 SIDs corresponding to the RAN IP prefix is ​​deleted from the correspondence table. In any of the communication systems, the first router may further include a table registration unit that automatically generates one or more IP prefixes that are longer than the Locator + Function length of the SRv6 SID by the Arg. Mob. Session length as IP prefixes to be registered in the correspondence table using configuration information that specifies one or more destination prefixes from route information registered in the VRF connected to the gNB and the Locator + Function length of the SRv6 SID set in the first router, automatically generates SRv6 SIDs corresponding to each of the automatically generated IP prefixes, and registers them in the correspondence table. The communication system may further include the controller.

[0005] According to one embodiment of the present invention, there is provided a router. The router may include a table storage unit that stores a correspondence table between IP prefixes of a network under the router and SRv6 SIDs with a Locator+Function length shorter than the IP prefix length corresponding to the IP prefix. The router may include a packet generation unit that, when receiving from another router an SRv6 packet including an SID that includes a portion of an address of a destination under the router and header information of a packet to be sent to the destination, refers to the correspondence table and identifies the address of the destination using the IP prefix corresponding to the SID included in the SRv6 packet and the portion of the destination address included in the SID, and generates a packet to be sent to the destination using the identified address and the header information included in the SID.

[0006] According to one embodiment of the present invention, there is provided a program for causing a computer to function as the router.

[0007] According to one embodiment of the present invention, there is provided a communication management method executed by a router. The communication management method may include a storage step of storing, in a table storage unit, a correspondence table between IP prefixes of a network subordinate to the router and SRv6 SIDs whose Locator+Function length is shorter than the IP prefix length corresponding to the IP prefix. The communication management method may include a packet generation step of, when an SRv6 packet is received from another router, including an SID that includes a portion of an address of a destination located under the router and header information of a packet to be sent to the destination, referring to the correspondence table and using the IP prefix corresponding to the SID included in the SRv6 packet and a portion of the destination address included in the SID to identify the address of the destination, and generating a packet to be sent to the destination using the identified address and the header information included in the SID.

[0008] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions.

[0009] FIG. 1 schematically illustrates an example of the configuration of a communication system 10. FIG. 2 is an explanatory diagram for roughly explaining a processing flow in the communication system 10. FIG. 3 is an explanatory diagram for roughly explaining an example of a GTP6.E. Reduced SID. FIG. 4 is an explanatory diagram for roughly explaining a GTP6.E. Reduced SID. FIG. 5 is an explanatory diagram for roughly explaining a GTP6.E. Reduced SID. FIG. 6 is an explanatory diagram for roughly explaining a GTP6.E. Reduced SID. FIG. 7 is an explanatory diagram for roughly explaining a functional configuration of a conversion unit 450. FIG. 8 is an explanatory diagram for roughly explaining an example of the functional configuration of a PE router 220. FIG. 9 is an explanatory diagram for roughly explaining an example of the hardware configuration of a computer 1200 that functions as an SRGW 400, a PE router 220, or an N4BGPC 300.

[0010] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0011] In a mobile network using SRv6, a function called End. M. GTP6.E is known that converts SRv6-compliant SRv6 packets into GTP-U packets that comply with GTP-U (GPRS Tunneling Protocol for User Plane). End. M. GTP6.E can convert the packet header from SRv6 to GTP-U / IPv6, for example, using the gNB (gNodeB) address stored in the LastSID (Segment ID) of the SRH (SR Header). However, End. M. GTP6. Depending on the limitations of the hardware capabilities of the PE (Provider Edge) router that implements E, it may be difficult to extract the gNB address stored in the LastSID of the SRH, and it may not be possible to configure the destination IPv6 address of the GTP-U packet.

[0012] In contrast, in one embodiment of the communication system 10 according to this embodiment, for example, all bits of the gNB address that is the destination after GTP-U conversion, and the TEID (Tunnel Endpoint IDentifier), QFI (QoS Flow Identifier), and RQI (Reflective QoS Indication) of the GTP-U header can be restored using only one SID. Such a function may be referred to as End. M. GTP6. E. Reduced (or GTP6. E. Red if omitted). GTP6. E. Red reduces the limitations on the hardware capabilities to be implemented. This can contribute to realizing packet conversion from SRv6 to GTP-U with more hardware.

[0013] FIG. 1 schematically illustrates an example of the configuration of a communication system 10. The communication system 10 includes a Segment Routing Gateway (SRGW) 400. The SRGW 400 may also be referred to as a Provider Edge (PE) router. The SRGW 400 may be an example of a first router. The communication system 10 may include a PE router 220. The PE router 220 may be an example of a second router. The communication system 10 may include an N4 Border Gateway Protocol Controller (N4BGPC) 300. The N4BGPC 300 may be an example of a controller. The SRGW 400, the PE router 220, and the N4BGPC 300 may be located within a Segment Routing Network (SRNW) 20.

[0014] The SRGW 400 may have a function of converting an SRv6 packet compliant with SRv6 received from an IP network into a GTP-U packet compliant with GTP-U. The SRGW 400 may have a function of converting a GTP-U packet compliant with GTP-U received from a mobile network into an SRv6 packet compliant with SRv6.

[0015] The N4BGPC 300 executes processing related to route control. The N4BGPC 300 may issue instructions related to route control to the SRGW 400. The N4BGPC 300 may issue instructions related to route control to the PE router 220.

[0016] 1, the SRNW 20 is provided with virtual routing and forwarding (VRF) 202, VRF 204, VRF 206, and VRF 208. Note that the illustration of the routers that realize each VRF is omitted. The SRGW 400 may include a VRF 210.

[0017] VRF 202 is connected to SMF (Session Management Function) 110. VRF 204, VRF 206, and VRF 208 are connected to UPF (User Plane Function) 120. VRF 210 is connected to gNB 130. VRF 210 may be connected to gNB 130 via a switch or router. While FIG. 1 illustrates one VRF 210, one gNB 130, and one UE 40, the numbers of VRFs 210, gNBs 130, and UEs 40 are not limited to this.

[0018] The N4BGPC 300 acquires information about the mobile network from the SMF 110. The N4BGPC 300 acquires, for example, Packet Forwarding Control Protocol (PFCP) session information of the UE 40 from the SMF 110.

[0019] The PFCP session information includes, for example, the address of the UE 40. The PFCP session information includes, for example, the address of the gNB 130 that accommodates the UE 40. The PFCP session information includes, for example, the address of the UPF 120 that corresponds to the UE 40. The PFCP session information includes, for example, a network instance that corresponds to the UE 40. The network instance is, for example, an access network instance, information that corresponds to slice identification information that can identify a slice that corresponds to the UE 40 in a mobile network. The slice identification information is, for example, S-NSSAI (Single-Network Slice Selection Assistance Information). The PFCP session information may include the access network instance. The PFCP session information may include a core network instance. The core network instance is, for example, information that corresponds to DN identification information that can identify a DN.

[0020] The SRGW 400 includes a conversion unit 410 and a conversion unit 450. The conversion unit 410 has a function of converting packets conforming to GTP-U into SRv6 packets conforming to SRv6. The conversion unit 410 may have a GTP4.D function. The conversion unit 410 may have a GTP6.D function.

[0021] The conversion unit 450 has a function of converting packets conforming to SRv6 into GTP-U packets conforming to GTP-U. The conversion unit 450 may have a GTP4.E function. The conversion unit 450 may have a GTP6.E function. In this embodiment, the conversion unit 450 may function as GTP6.E.Red.

[0022] In this embodiment, N4BGPC300 performs route setting to relay communication between UE (User Equipment) 40 connected to gNB130 and a communication partner connected to DN30. The communication partner of UE40 may be, for example, any communication device such as any server on the Internet.

[0023] 2 is an explanatory diagram for outlining the flow of processing in the communication system 10. Here, an example of the flow of processing after the SRGW 400 stores the correspondence table 480 and the N4BGPC 300 transmits the UE route information of the UE 40 to the PE router 220 will be described.

[0024] The correspondence table 480 registers IP prefixes of RANs (Radio Access Networks) under the SRGW 400 and SRv6 SIDs that correspond to the IP prefixes and have a Locator+Function length that is shorter than the IP prefix length. The correspondence table 480 may include multiple combinations of IP prefixes and SRv6 SIDs.

[0025] As an example, if the terminal address is 2001:0db8:0123:4567:89ab:cdef:0123:4567 and the network to which the terminal is connected is 2001:0db8:0123:4567:: / 64, normally 2001:0db8:0123:4567:: / 64 would be advertised to the network. However, in the communication system 10 according to this embodiment, when the Locator+Function length of the SRv6 SID of the SRGW 400 is 48 bits, 2001:0db8:0123:4567:89ab:cd00:: / 88 is advertised. 2, for the RAN IP Prefix 2001:0db8:0123:4567:89ab:cd00:: / 88, fc00:0123:4567:: / 48 is registered in the correspondence table 480 as the Locator+Function of the 48-bit SRv6 SID. As a result, when the SRGW 400 receives the SRv6 SID fc00:0123:4567:: / 48, it can extract 2001:0db8:0123:4567:89ab:cd00:: / 88 by referring to the correspondence table 480. In this example, to restore the terminal address, it is necessary to include the last 40 bits of the terminal address in the SRv6 SID, but it is possible to freely use the other parts.

[0026] As in this example, the IP prefix to be registered in the correspondence table 480 may be registered with a prefix length longer than the IP prefix of the network to which the gNB 130 is connected. The SRv6 SID corresponding to the IP prefix to be registered in the correspondence table 480 may be set manually by an administrator, or may be set externally. The SRGW 400 may automatically generate the SRv6 SID corresponding to the IP prefix to be registered in the correspondence table 480. The SRGW 400 uses configuration information that specifies one or more destination prefixes from the route information registered in the VRF 210 and the Locator+Function length of the SRv6 SID set in the SRGW 400 to determine the Arg. Mob. 0x0 ... The SRGW 400 may automatically generate one or more long IP prefixes corresponding to the session length. The SRGW 400 may automatically generate an SRv6 SID corresponding to each of the automatically generated IP prefixes and register the SRv6 SIDs in the correspondence table 480.

[0027] In this example, first, the SRGW 400 advertises a BGP-MUP SAFI Interwork Segment Discovery Route (sometimes referred to as an ISD route). The ISD route indicates GTP6.E.Reduced as the SID Behavior for the SRv6 SID stored in the BGP attribute that stores the SRv6 SID, and adds Arg.Mob.Session to the NLRI if the actual RAN IP Prefix length including the RAN IP Prefix corresponding to the SID is shorter than the SID Locator+Function length and the Arg.Mob.Session length. A RAN IP prefix having the same length as the Locator+Function+Arg. Mob. Session length of the SID, including a stuff area for embedding the Session, may be stored.

[0028] When a route having a destination prefix including a RAN IP prefix having a stuff area for embedding an Arg. Mob. Session from VRF 210 disappears, or when reachability to the IP prefix disappears, SRGW 400 may delete the pair of the RAN IP prefix and the corresponding SRv6 SID from correspondence table 480 and perform a withdrawn route advertisement (withdrawal) of an ISD route having the RAN IP prefix in its NLRI.

[0029] When the gNB address included in the UE route information received from N4BGPC 300 is included in the IP prefix stored in the NLRI of the ISD route received from SRGW 400 including the stuff area, and the SRv6 SID indicates GTP6. E. Reduced as Behavior, the PE router 220 stores the Argument field in the SID, and stores the Arg. Mob. Session consisting of the TEID, QFI, and RQI included in the UE route information received from N4BGPC 300. If there are any remaining Argument bits, the value of the gNB address in the same bit position as the remaining bits is stored to generate a GTP6. E. Reduced SID for transmitting packets destined for UE 40 to SRGW 400. If the gNB address included in the UE route information received from N4BGPC 300 is not included in the IP prefix stored in the NLRI of the ISD route received from SRGW 400 including the stuff area, the SRv6 SID of the ISD route is used. GTP6. E. Reduced SID is not generated.

[0030] When the SRGW 400 receives an SRv6 packet having a GTP6. E. Reduced SID as the active SID from the PE router 220, it acquires the Arg. Mob. Session from the SID, and acquires the RAN IP prefix including the value of the stuff field for embedding the Arg. Mob. Session corresponding to the SID, and the value of the gNB address at the same bit position as the remaining bit. The complete gNB address is acquired, and the gNB address is used as the destination address of the GTP-U packet. The TEID, QFI, and RQI values ​​are acquired from the Arg. Mob. Session to generate a GTP-U packet and transmit it to the gNB 130.

[0031] 3 is an explanatory diagram for explaining an example of GTP6.E. Reduced SID. In order to convert an SRv6 packet into a GTP-U packet, the conversion unit 450 of the SRGW 400 needs to extract a 128-bit gNB address and a 40-bit GTP-U packet parameter from one 128-bit SID, but since it is 168 bits in total, it cannot be directly included in the 128-bit SID. Therefore, in the communication system 10 according to this embodiment, a correspondence table 480 is used.

[0032] Typically, the prefix length in IPv6 is 64 bits, and normally, a 64-bit prefix (actual prefix) is advertised. In contrast, in communication system 10, when the Locator+Function length of the GTP6.E. Reduced SID is 48 bits, the actual prefix is ​​advertised including a 24-bit stuff field to enable later extraction of the 40-bit Arg. Mob. Session.

[0033] The PE router 220 generates a GTP6.E. Reduced SID that stores a 40-bit Argument field and the lower 40 bits of the gNB address included in the UE route information in the 80-bit Argument field. The PE router 220 includes the TEID, QFI, and RQI included in the UE route information received from the N4BGPC 300 in the Arg. Mob. Session.

[0034] The upper 88 bits of the gNB address can be obtained by referencing the correspondence table 480 based on the Locator + Function of the GTP6.E. Reduced SID, as shown by the dashed line in FIG. 3. The lower 40 bits of the gNB address are stored at the end of the GTP6.E. Reduced SID, so the conversion unit 450 can obtain a 128-bit gNB address using these. In addition, the conversion unit 450 can also obtain information about the Arg. Mob. Session. The conversion unit 450 can generate a GTP-U packet using the obtained 128-bit gNB address as the destination address and setting the TEID, QFI, and RQI obtained from the Arg. Mob. Session.

[0035] 4 is an explanatory diagram for explaining the outline of the GTP6.E. Reduced SID, in which a stuff field is included in the NLRI of the ISD root.

[0036] If the size of the Locator+Function of SID 502 in the ISD route is b, the size of the Argument is 128-b. If the length of the RAN IP Prefix corresponding to the SID is a, the conversion unit 450 stores, in the ISD route, RAN IP Prefix 504 of the same length as the Locator+Function+Arg.Mob.Session length of SID 508 (i.e., b+40), including a stuff area (40-a+b) for embedding Arg.Mob.Session in the NLRI.

[0037] When the gNB address included in the UE route information received from N4BGPC 300 is included in the IP prefix stored in the NLRI of the ISD route received from SRGW 400 including the stuff area, PE router 220 stores the Argument area, in which the Argument area contains the TEID, QFI, and RQI included in the UE route information received from N4BGPC 300. Mob. Session is stored, and the remaining bits (128-40-b) contain the value of the gNB address 506 at the same bit position as the remaining bits, thereby generating SID 508.

[0038] 5 is an explanatory diagram for explaining the outline of the GTP6.E. Reduced SID. Here, we will explain the case where the stuff field is not included in the NLRI of the ISD root. If the size of the argument is secured, there is no need to include the stuff field.

[0039] In the example shown in FIG. 5, the RAN IP Prefix length corresponding to the SID is a, the size of the Locator+Function of SID512 of the ISD route is a-40, the size of the Argument is 128-(a-40), the size of the Locator+Function of SID518 is a-40, and the size of the Arg. Mob. Session is 40, so the stuff area is 40-a+(a-40)=0, and no stuff area is required.

[0040] 6 shows an example of the functional configuration of the conversion unit 450. The conversion unit 450 includes a storage unit 452, an advertising unit 454, a packet receiving unit 456, a packet generating unit 458, a packet transmitting unit 460, and a table management unit 462. It is not essential that the conversion unit 450 include all of these units.

[0041] The storage unit 452 stores various types of information. The storage unit 452 stores a correspondence table 480 between IP prefixes of a network subordinate to the SRGW 400 and SRv6 SIDs that correspond to the IP prefixes and have a Locator+Function length that is shorter than the IP prefix length. The storage unit 452 may store a correspondence table 480 between IP prefixes of a RAN subordinate to the SRGW 400 and SRv6 SIDs that correspond to the IP prefixes and have a shorter IP prefix length than the IP prefix length. The storage unit 452 may be an example of a table storage unit.

[0042] The advertising unit 454 advertises the ISD route of the BGP-MUP SAFI. The ISD route indicates GTP6.E.Reduced as the SID Behavior for the SRv6 SID stored in the BGP attribute that stores the SRv6 SID, and when the actual IP prefix length including the IP prefix corresponding to the SID is shorter than the Arg.Mob.Session length compared to the SID Locator+Function length, the ISD route may store an IP prefix of the same length as the SID's Locator+Function length+Arg.Mob.Session length, including a stuff area for embedding the Arg.Mob.Session, in the NLRI.

[0043] The packet receiving unit 456 receives an SRv6 packet from the PE router 220. For example, the packet receiving unit 456 receives from the PE router 220 an SRv6 packet that has been generated by the PE router 220 and has an SID that includes part of the address of a destination located under the SRGW 400 and header information of a packet to be sent to that destination.

[0044] When the packet receiver 456 receives an SRv6 packet from the PE router 220, the packet generator 458 refers to the correspondence table 480 stored in the storage unit 452 to identify the IP prefix corresponding to the SID included in the SRv6 packet. The packet generator 458 identifies the destination address using the identified IP prefix and a portion of the destination address included in the SID included in the SRv6 packet. The packet generator 458 generates a packet to be sent to the destination using the identified address and header information included in the SID included in the SRv6 packet.

[0045] Further, for example, the packet receiving unit 456 receives from the PE router 220 an SRv6 packet having an SID including a portion of the gNB address of the gNB 130 to which the UE 40 is connected and header information, which was generated by the PE router 220. The packet generating unit 458 may identify the gNB address using an IP prefix corresponding to the SID included in the SRv6 packet and a portion of the gNB address included in the SID included in the SRv6 packet. The packet generating unit 458 may generate a GTP-U packet to be transmitted to the gNB using the identified gNB address and the header information. The packet generating unit 458 may generate a GTP-U packet using the identified gNB address and the TEID, QFI, and RQI included in the header information. The packet generating unit 458 may generate a GTP-U packet with the identified gNB address as the destination address and with the TEID, QFI, and RQI included in the header information set.

[0046] The packet transmitting unit 460 transmits the packets generated by the packet generating unit 458. The packet transmitting unit 460 transmits the GTP-U packets generated by the packet generating unit 458.

[0047] When a route having a destination prefix including a RAN IP prefix having a stuff area for embedding Arg. Mob. Session from VRF 210 connected to gNB 130 is lost, or when reachability to the IP prefix is ​​lost, the table management unit 462 may delete the pair of the RAN IP prefix and the corresponding SRv6 SID from the correspondence table 480. When the pair of the RAN IP prefix and the corresponding SRv6 SID is deleted from the correspondence table 480, the advertising unit 454 may perform a withdrawal route advertisement for an ISD route having the RAN IP prefix in its NLRI.

[0048] The table management unit 462 may execute registration in the correspondence table 480. For example, the table management unit 462 may use configuration information specifying one or more destination prefixes from the route information registered in the VRF 210 connected to the gNB 130 and the Locator+Function length of the SRv6 SID set in the SRGW 400 to automatically generate one or more IP prefixes that are longer than the Locator+Function length of the SRv6 SID by the Arg. Mob. Session length as the IP prefix to be registered in the correspondence table 480. The table management unit 462 may automatically generate an SRv6 SID corresponding to each of the automatically generated IP prefixes and register them in the correspondence table 480.

[0049] 7 shows an example of the functional configuration of the PE router 220. The PE router 220 includes a storage unit 222, a route information receiving unit 224, an SID generating unit 226, and a packet transmitting unit 228.

[0050] The route information receiving unit 224 receives UE route information of the UE 40. The route information receiving unit 224 receives, for example, UE route information including the gNB address of the gNB to which the UE 40 is connected, advertised by the N4BGPC 300. The route information receiving unit 224 stores the received UE route information in the storage unit 222.

[0051] The route information receiving unit 224 receives the ISD route from the SRGW 400. The route information receiving unit 224 stores the received ISD route in the storage unit 222.

[0052] The SID generation unit 226 generates an SID that includes a portion of the address of a destination located under the SRGW 400 and header information of a packet to be sent to the destination. For example, the SID generation unit 226 generates an SID that includes a portion of the destination gNB address and header information that includes the TEID, QFI, and RQI included in the UE route information received by the route information reception unit 224. If the IP prefix of the ISD route received from the SRGW 400 and the gNB address included in the UE route information exactly match, the generated SID does not need to include a portion of the gNB address.

[0053] When the Behavior of the SRv6 SID of the ISD route received by the route information receiving unit 224 from the SRGW 400 indicates GTP6.E. Reduced, the SID generating unit 226 may generate an SID by storing Arg. Mob. Session in the Argument field within the SID and storing the value of the gNB address in the same bit position as the remaining bits in the remaining Argument bits. The Arg. Mob. Session may be configured with header information including the TEID, QFI, and RQI included in the UE route information. When the packet receiving unit 456 receives an SRv6 packet having a GTP6.E. Reduced SID as the active SID, the packet generating unit 458 of the conversion unit 450 generates the Arg. Mob. Session from the SID. The Arg. Mob. Session may be obtained, the gNB address may be identified from the IP prefix including the stuff area and the value of the gNB address at the same bit position as the remaining bit, and the TEID, QFI, and RQI may be obtained from the Arg. Mob. Session.

[0054] The packet transmitting unit 228 transmits an SRv6 packet including the SID generated by the SID generating unit 226. The packet transmitting unit 228 transmits the SRv6 packet to the SRGW 400.

[0055] 8 schematically illustrates an example of the hardware configuration of a computer 1200 functioning as the SRGW 400, the PE router 220, or the N4BGPC 300. A program installed on the computer 1200 can cause the computer 1200 to function as one or more "parts" of an apparatus according to the present embodiment, or can cause the computer 1200 to perform operations associated with the apparatus according to the present embodiment or one or more "parts" thereof, and / or can cause the computer 1200 to perform a process according to the present embodiment or steps of the process. Such a program can be executed by the CPU 1212 to cause the computer 1200 to perform specific operations associated with some or all of the blocks in the flowcharts and block diagrams described herein.

[0056] The computer 1200 according to this embodiment includes a CPU 1212, a RAM 1214, and a graphics controller 1216, which are interconnected by a host controller 1210. The computer 1200 also includes input / output units such as a communications interface 1222, a storage device 1224, a DVD drive, and an IC card drive, which are connected to the host controller 1210 via an input / output controller 1220. The DVD drive may be a DVD-ROM drive, a DVD-RAM drive, or the like. The storage device 1224 may be a hard disk drive, a solid-state drive, or the like. The computer 1200 also includes a ROM 1230 and a legacy input / output unit such as a keyboard, which are connected to the input / output controller 1220 via an input / output chip 1240.

[0057] The CPU 1212 operates according to programs stored in the ROM 1230 and the RAM 1214, thereby controlling each unit. The graphics controller 1216 acquires image data generated by the CPU 1212 into a frame buffer or the like provided in the RAM 1214 or into the graphics controller 1216 itself, and causes the image data to be displayed on the display device 1218.

[0058] The communication interface 1222 communicates with other electronic devices via a network. The storage device 1224 stores programs and data used by the CPU 1212 in the computer 1200. The DVD drive reads programs or data from a DVD-ROM or the like and provides them to the storage device 1224. The IC card drive reads programs and data from an IC card and / or writes programs and data to an IC card.

[0059] The ROM 1230 stores therein a boot program or the like that is executed by the computer 1200 upon activation, and / or programs that depend on the hardware of the computer 1200. The input / output chip 1240 may also connect various input / output units to the input / output controller 1220 via a USB port, a parallel port, a serial port, a keyboard port, a mouse port, etc.

[0060] The programs are provided by a computer-readable storage medium such as a DVD-ROM or an IC card. The programs are read from the computer-readable storage medium, installed in the storage device 1224, RAM 1214, or ROM 1230, which are also examples of computer-readable storage media, and executed by the CPU 1212. Information processing described in these programs is read by the computer 1200, and brings about cooperation between the programs and the various types of hardware resources described above. An apparatus or a method may be configured by implementing operations or processing of information in accordance with the use of the computer 1200.

[0061] For example, when communication is performed between computer 1200 and an external device, CPU 1212 may execute a communication program loaded into RAM 1214 and instruct communication interface 1222 to perform communication processing based on the processing described in the communication program. Under the control of CPU 1212, communication interface 1222 reads transmission data stored in a transmission buffer area provided in RAM 1214, storage device 1224, a DVD-ROM, or a recording medium such as an IC card, and transmits the read transmission data to a network, or writes received data received from the network to a reception buffer area or the like provided on the recording medium.

[0062] Furthermore, the CPU 1212 may cause all or a necessary portion of a file or database stored in an external recording medium such as the storage device 1224, a DVD drive (DVD-ROM), an IC card, etc. to be read into the RAM 1214, and may perform various types of processing on the data on the RAM 1214. The CPU 1212 may then write back the processed data to the external recording medium.

[0063] Various types of information, such as various types of programs, data, tables, and databases, may be stored on the recording medium and may undergo information processing. The CPU 1212 may perform various types of processing on data read from the RAM 1214, including various types of operations, information processing, conditional judgment, conditional branching, unconditional branching, information search / replacement, etc., as described throughout this disclosure and specified by the instruction sequences of the programs, and write the results back to the RAM 1214. The CPU 1212 may also search for information in a file, database, etc. on the recording medium. For example, if multiple entries, each having an attribute value of a first attribute associated with an attribute value of a second attribute, are stored on the recording medium, the CPU 1212 may search for an entry whose attribute value of the first attribute matches a specified condition from among the multiple entries, read the attribute value of the second attribute stored in the entry, and thereby obtain the attribute value of the second attribute associated with the first attribute that satisfies a predetermined condition.

[0064] The above-described programs or software modules may be stored in a computer-readable storage medium on or near the computer 1200. A recording medium such as a hard disk or RAM provided in a server system connected to a dedicated communication network or the Internet can also be used as a computer-readable storage medium, thereby providing the programs to the computer 1200 via the network.

[0065] The blocks in the flowcharts and block diagrams in the present embodiments may represent stages of a process in which an operation is performed or "parts" of a device responsible for performing the operation. Particular stages and "parts" may be implemented by dedicated circuitry, programmable circuitry provided with computer-readable instructions stored on a computer-readable storage medium, and / or a processor provided with computer-readable instructions stored on a computer-readable storage medium. The dedicated circuitry may include digital and / or analog hardware circuits, and may include integrated circuits (ICs) and / or discrete circuits. The programmable circuitry may include reconfigurable hardware circuits, such as field programmable gate arrays (FPGAs) and programmable logic arrays (PLAs), including AND, OR, XOR, NAND, NOR, and other logical operations, flip-flops, registers, and memory elements.

[0066] A computer-readable storage medium may include any tangible device capable of storing instructions that are executed by an appropriate device, such that a computer-readable storage medium having instructions stored thereon comprises an article of manufacture, including instructions that can be executed to create means for performing the operations specified in the flowcharts or block diagrams. Examples of computer-readable storage media may include electronic, magnetic, optical, electromagnetic, and semiconductor storage media. More specific examples of computer-readable storage media may include floppy disks, diskettes, hard disks, random access memories (RAMs), read-only memories (ROMs), erasable programmable read-only memories (EPROMs or flash memories), electrically erasable programmable read-only memories (EEPROMs), static random access memories (SRAMs), compact disc read-only memories (CD-ROMs), digital versatile discs (DVDs), Blu-ray discs, memory sticks, integrated circuit cards, and the like.

[0067] The computer readable instructions may include either assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state-setting data, or source or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk®, JAVA®, C++, etc., and conventional procedural programming languages ​​such as the “C” programming language or similar programming languages.

[0068] Computer-readable instructions may be provided locally or over a local area network (LAN), a wide area network (WAN) such as the Internet, to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, or programmable circuitry, such that the processor or programmable circuitry executes the computer-readable instructions to generate means for performing the operations specified in the flowcharts or block diagrams. Examples of processors include computer processors, processing units, microprocessors, digital signal processors, controllers, microcontrollers, etc.

[0069] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0070] It should be noted that the execution order of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order.

[0071] 10 Communication system, 20 SRNW, 30 DN, 40 UE, 110 SMF, 120 UPF, 130 gNB, 202, 204, 206, 208, 210 VRF, 220 PE router, 222 Memory unit, 224 Route information receiving unit, 226 SID generating unit, 228 Packet transmitting unit, 300 N4BGPC, 400 SRGW, 410 Conversion unit, 450 Conversion unit, 452 Memory unit, 454 Advertising unit, 456 Packet receiving unit, 458 Packet generating unit, 460 Packet transmitting unit, 462 Table management unit, 480 Correspondence table, 502 SID, 504 RAN IP Prefix, 506 gNB address, 508 SID, 512 SID, 514 RAN IP Prefix, 516 gNB address, 518 SID, 1200 Computer, 1210 Host controller, 1212 CPU, 1214 RAM, 1216 Graphics controller, 1218 Display device, 1220 Input / output controller, 1222 Communication interface, 1224 Storage device, 1230 ROM, 1240 Input / output chip

Claims

1. A device comprising: a first router; and a second router, wherein the first router has a table storage unit that stores a correspondence table between IP prefixes of a network under the first router and SRv6 SIDs with a Locator+Function length shorter than the IP prefix length corresponding to the IP prefix, and the second router has: a SID generation unit that generates an SID including a part of a destination address located under the first router and header information of a packet to be transmitted to the destination, and a packet transmission unit that transmits an SRv6 packet including the SID generated by the SID generation unit to the first router, a packet generating unit configured to, when receiving the SRv6 packet from the second router, refer to the correspondence table to identify an IP prefix corresponding to the SID included in the SRv6 packet, identify an address of the destination using the identified IP prefix and a part of the address of the destination included in the SID, and generate a packet to be sent to the destination using the identified address and the header information included in the SID.

2. The communication system of claim 1, wherein the first router is a PE router that converts SRv6 packets conforming to SRv6 into GTP-U packets conforming to GTP-U, the table storage unit stores the correspondence table between IP prefixes of RANs subordinate to the first router and the SRv6 SIDs, the second router has a route information receiving unit that receives UE route information including a gNB address of a gNB to which a UE is connected, advertised by a controller, the SID generating unit generates the SID including a portion of the gNB address and the header information, and the packet generating unit identifies the gNB address using an IP prefix corresponding to the SID included in the SRv6 packet and a portion of the gNB address included in the SID, and generates a GTP-U packet to be transmitted to the gNB using the identified gNB address and the header information.

3. The communication system of claim 2, wherein the SID generation unit generates the SID including a portion of the gNB address and header information including a TEID, QFI, and RQI included in the UE route information, and the packet generation unit generates the GTP-U packet using the identified gNB address and the TEID, QFI, and RQI included in the header information.

4. The first router has an advertisement unit that advertises an ISD (Interwork Segment Discovery) route, and the ISD route indicates GTP6.E.Reduced as SID Behavior in a BGP attribute that stores an SRv6 SID, and when an actual RAN IP prefix length including an IP prefix of a RAN under the first router corresponding to the SID is shorter than an Arg. Mob. Session length compared to an SID Locator / Function length, the second router adds the Locator / Function length of the SID and the Arg. Mob. Session length including a stuff area for embedding the Arg. Mob. Session in the SID to the NLRI. The SID generation unit stores an IP prefix having the same length as the NLRI length of the gNB address included in the UE route information, and when the gNB address included in the UE route information is included in the IP prefix stored in the NLRI of the ISD route received from the first router including the stuff area, and when the Behavior of the SRv6 SID indicates GTP6.E. Reduced, the SID generation unit generates the SID by storing an Arg. Mob. Session consisting of the header information including the TEID, the QFI, and the RQI included in the UE route information in an Argument area within the SID, and storing the value of the gNB address at the same bit position as the remaining bits in the remaining Argument bits, and when the packet generation unit receives an SRv6 packet having a GTP6.E. Reduced SID as an active SID, the packet generation unit generates the SID by storing the Arg. Mob. Session consisting of the header information including the TEID, the QFI, and the RQI included in the UE route information in an Argument area within the SID, and storing the value of the gNB address at the same bit position as the remaining bits in the remaining Argument bits, and 4. The communication system according to claim 3, further comprising: acquiring an Arg. Mob. Session; identifying the gNB address from the IP prefix including the stuff area and the value of the gNB address at the same bit position as the remaining bit; and acquiring the TEID, the QFI, and the RQI from the Arg. Mob. Session.

5. The first router is provided with a table management unit that deletes a pair of the RAN IP prefix and the corresponding SRv6 SID from the correspondence table when a route having a destination prefix including a RAN IP prefix having a stuff area for embedding an Arg. Mob. Session from a VRF connected to the gNB is lost or reachability to the IP prefix is ​​lost, and the advertising unit performs a withdrawal route advertisement of an ISD route having the RAN IP prefix in its NLRI when the pair of the RAN IP prefix and the corresponding SRv6 SID is deleted from the correspondence table. The communication system according to claim 4.

6. The first router uses configuration information specifying one or more destination prefixes from route information registered in the VRF connected to the gNB and the Locator + Function length of the SRv6 SID set in the first router to automatically generate one or more IP prefixes longer than the Locator + Function length of the SRv6 SID by the Arg. Mob. Session length as an IP prefix to be registered in the correspondence table, and automatically generates SRv6 SIDs corresponding to each of the automatically generated IP prefixes and registers them in the correspondence table. The communication system according to any one of claims 2 to 5, further comprising a table registration unit.

7. A communication system according to any one of claims 2 to 6, further comprising the controller.

8. A router comprising: a table storage unit that stores a correspondence table between IP prefixes of a network under the router and SRv6 SIDs with a Locator+Function length shorter than the IP prefix length corresponding to the IP prefix; and a packet generation unit that, when receiving from another router an SRv6 packet including an SID that includes part of an address of a destination under the router and header information of a packet to be sent to the destination, refers to the correspondence table, and uses the IP prefix corresponding to the SID included in the SRv6 packet and part of the address of the destination included in the SID to identify the address of the destination, and generates a packet to be sent to the destination using the identified address and the header information included in the SID.

9. A program for causing a computer to function as the router according to claim 8.

10. A communication management method executed by a router, comprising: a storage step of storing in a table storage unit a correspondence table between IP prefixes of a network under the router and SRv6 SIDs with a Locator+Function length shorter than the IP prefix length corresponding to the IP prefix; and a packet generation step of, when an SRv6 packet including an SID including a part of a destination address located under the router and header information of a packet to be sent to the destination, referring to the correspondence table, specifying the address of the destination using the IP prefix corresponding to the SID included in the SRv6 packet and a part of the destination address included in the SID, and generating a packet to be sent to the destination using the specified address and the header information included in the SID, when an SRv6 packet including an SID including a part of a destination address located under the router and header information of a packet to be sent to the destination is received from another router.

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