COMMUNICATION SYSTEM, COMMUNICATION METHOD, AND COMMUNICATION PROGRAM

Abstract

A communication system (1) according to the present invention comprises a distribution device (100), a first transferring device (200A), and a second transferring device (200B). The distribution device (100) distributes information regarding a communication path to the first transferring device (200A) and the second transferring device (200B). The first transferring device (200A) and the second transferring device (200B) use the information regarding the communication path to perform encap / decap of packets transmitted from a terminal, and make communication with a terminal which is a destination possible via a first transferring device (200A) or a second transferring device (200B) existing in a different VPN.

Description

[Technical Field]

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

[0002] In conventional communication formats, after communication reaches the core network, it is transferred to a different network via the Internet or by using a core network connection. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 250726 [Non-patent literature]

[0004] [Non-Patent Document 1] IETF “Segment Routing IPv6 for Mobile User Plane draft-ietf-dmm-srv6-mobile-uplane-21”(https: / / datatracker.ietf.org / doc / html / draft-ietf-dmm-srv6-mobile-uplane-21) Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional technologies have the problem of being limited in terms of providing low latency and closed network functionality, because the conventional communication formats do not allow for network allocation or network integration in the access network due to the tunneling of each network.

[0006] The present invention has been made in view of the above, and has an object to provide a communication system, a communication method, and a communication program that enable suppression of delays and improvement of closed-area performance. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the communication system of the present invention comprises a distribution device, a first forwarding device, and a second forwarding device, wherein the distribution device comprises a first acquisition unit that acquires information regarding a communication path, and a distribution unit that transmits the information regarding the communication path acquired by the first acquisition unit to the first forwarding device and the second forwarding device, and the first forwarding device and the second forwarding device each comprise a second acquisition unit that acquires a packet and the information regarding the communication path distributed by the distribution unit, a first determination unit that determines whether the destination IP address of the packet acquired by the second acquisition unit matches the information regarding the communication path acquired by the second acquisition unit, a first rewriting unit that rewrites the header of the packet acquired by the second acquisition unit based on the information regarding the communication path acquired by the second acquisition unit when the first determination unit determines that there is a match, and a first transmission unit that transmits the packet whose header has been rewritten by the first rewriting unit to the first forwarding device or the second forwarding device that exists in a different VPN. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress delays and improve closed-area performance. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram for explaining an outline of a communication system according to this embodiment. [Figure 2] FIG. 2 is a block diagram showing the configuration of the distribution device of this embodiment. [Figure 3] FIG. 3 is a block diagram showing the configuration of the transfer device of this embodiment. [Figure 4] FIG. 4 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 5] FIG. 5 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 6]FIG. 6 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 7] FIG. 7 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 8] FIG. 8 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 9] FIG. 9 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 10] FIG. 10 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 11] FIG. 11 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 12] FIG. 12 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 13] FIG. 13 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 14] FIG. 14 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 15] FIG. 15 is a diagram for explaining the processing performed by the communication system of this embodiment. [Figure 16] FIG. 16 is a diagram summarizing information about routes used by the communication system of this embodiment. [Figure 17] FIG. 17 is a flowchart showing the processing procedure performed by the transfer device of this embodiment. [Figure 18] FIG. 18 is a flowchart showing the processing procedure performed by the transfer device of this embodiment. [Figure 19] FIG. 19 is a diagram illustrating an example of a computer that executes a communication program. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, with reference to the drawings, embodiments of a communication system, a communication method, and a communication program according to the present application will be described in detail. Note that the present invention is not limited to these embodiments. In addition, in the description of the drawings, the same parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0011] [Communication System Overview] An overview of the communication system 1 of this embodiment will be described using FIG. 1. First, the distribution device 100 distributes information about communication paths to the first transfer device 200A and the second transfer device 200B. Next, the first transfer device 200A or the second transfer device 200B performs packet analysis and determines whether the packet has an IP address to be controlled, using information about the communication path acquired in advance and information about the communication path created from the packet at the time of transmission. Then, if the communication is to be controlled, the first transfer device 200A or the second transfer device 200B encapsulates / decapsulates the header and resolves protocol differences between the heterogeneous networks, thereby realizing communication between heterogeneous networks. As a result, in addition to communication in which direct tunnels are established from the conventional transfer devices to each core network, a tunnel directly connecting the first transfer device 200A and the second transfer device 200B can be established.

[0012] [Communication system configuration] The configuration of a communication system 1 will be described using Fig. 1. As shown in Fig. 1, the communication system 1 includes a distribution device 100, a first transfer device 200A, and a second transfer device 200B. In the communication system 1, the first transfer device 200A and the second transfer device 200B are assumed to exist in different VPNs. The distribution device 100 distributes information required for entering a heterogeneous network to the first transfer device 200A and the second transfer device 200B.

[0013] The first transfer device 200A transmits a packet to be entered to the second transfer device 200B based on information about the communication path distributed by the distribution device 100. The second transfer device 200B transmits the packet transmitted by the first transfer device 200A to a mobile terminal or a fixed terminal based on information about the communication path distributed by the distribution device 100 or information about the communication path created by the first transfer device 200A.

[0014] [Distribution device configuration] Next, the configuration of the broadcasting device 100 will be described with reference to Fig. 2. As shown in Fig. 2, the broadcasting device 100 has a communication unit 110, a control unit 120, and a storage unit 130. Note that these units may be distributed and held by multiple devices. The processing of these units will be described below.

[0015] The communication unit 110 is realized by a NIC (Network Interface Card) or the like, and enables communication between an external device and the control unit 120 via a telecommunication line such as a LAN (Local Area Network) or the Internet. For example, the communication unit 110 enables communication between the external device and the control unit 120.

[0016] The storage unit 130 is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, or a storage device such as a hard disk or an optical disk. The information stored in the storage unit 130 includes, for example, information on an IP address pool, information on destination IP addresses that are subject to heterogeneous network allocation, information on routes to routers that accommodate terminals having destination IP addresses that are subject to heterogeneous network allocation, information linking the IP addresses of mobile terminals with GTP-U tunnel information, and other information necessary for heterogeneous network transfer. Note that the information stored in the storage unit 130 is not limited to the information described above.

[0017] The control unit 120 is realized using a CPU (Central Processing Unit), an NP (Network Processor), an FPGA (Field Programmable Gate Array), etc., and executes a processing program stored in a memory. As shown in Fig. 2, the control unit 120 has a first acquisition unit 121 and a distribution unit 122. Each unit of the control unit 120 will be described below.

[0018] The first acquisition unit 121 acquires information about the communication path. For example, the first acquisition unit 121 acquires, as information about the communication path, information about an IP address pool, information about a destination IP address that is a target of heterogeneous network allocation, and information about a path to a router that accommodates a terminal having a destination IP address that is a target of heterogeneous network allocation, from the storage unit 130.

[0019] The distribution unit 122 distributes information about the communication paths acquired by the first acquisition unit 121 to the first transfer device 200A and the second transfer device 200B. For example, the distribution unit 122 distributes information about IP address pools, information about destination IP addresses that are the subject of heterogeneous network allocation, and information about paths to routers that accommodate terminals that have destination IP addresses that are the subject of heterogeneous network allocation, all acquired by the first acquisition unit 121, to the first transfer device 200A and the second transfer device 200B.

[0020] [Transfer Device Configuration] Next, the configuration of the transfer device 200 will be described using Fig. 3. As shown in Fig. 3, the transfer device 200 has a communication unit 210, a control unit 220, and a storage unit 230. Note that each of these units may be held in a distributed manner by multiple devices. The processing of each of these units will be described below.

[0021] The communication unit 210 is realized by a NIC (Network Interface Card) or the like, and enables communication between an external device and the control unit 220 via an electric communication line such as a LAN (Local Area Network) or the Internet. For example, the communication unit 210 enables communication between the external device and the control unit 220.

[0022] The storage unit 230 is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, or a storage device such as a hard disk or an optical disk. The information stored in the storage unit 230 includes, for example, an IP address pool, a destination IP address to be subject to heterogeneous network allocation, route information to a router that accommodates a terminal having a destination IP address to be subject to heterogeneous network allocation, information linking the IP address of a mobile terminal with GTP-U tunnel information, and other information necessary for heterogeneous network transfer. Note that the information stored in the storage unit 230 is not limited to the above.

[0023] The control unit 220 is realized using a CPU (Central Processing Unit), an NP (Network Processor), an FPGA (Field Programmable Gate Array), or the like, and executes a processing program stored in a memory. As shown in Fig. 3, the control unit 220 has a second acquisition unit 221a, a third acquisition unit 221b, a first determination unit 222a, a second determination unit 222b, a first judgment unit 223a, a second judgment unit 223b, a first rewriting unit 224a, a second rewriting unit 224b, a creation unit 225, a processing unit 226, a first transmission unit 227a, and a second transmission unit 227b. Each unit of the control unit 220 will be described below.

[0024] The second acquisition unit 221a acquires packets and information about the communication path distributed by the distribution unit 122. For example, the second acquisition unit 221a acquires information about an IP address pool, information about destination IP addresses that are the target of heterogeneous network allocation, and information about paths to routers that accommodate terminals that have destination IP addresses that are the target of heterogeneous network allocation, as information about the communication path distributed by the distribution unit 122. Furthermore, for example, the second acquisition unit 221a acquires information that links the IP address of a mobile terminal with GTP-U tunnel information from C-Plane communication, as information about the communication path.

[0025] The first determination unit 222a determines whether a predetermined protocol is used in the packet acquired by the second acquisition unit 221a. For example, the first determination unit 222a determines whether GTP-U (GPRS Tunneling Protocol For User Plane) is used in the packet acquired by the second acquisition unit 221a. Also, for example, the first determination unit 222a determines whether a QinQ tag is included in the packet acquired by the second acquisition unit 221a. Note that the above is an example and does not limit the predetermined protocol used for determination by the first determination unit 222a.

[0026] The first determination unit 223a determines whether the destination IP address of the packet acquired by the second acquisition unit 221a matches the information about the communication path acquired by the second acquisition unit 221a. Furthermore, for example, when the first determination unit 222a determines that a predetermined protocol is used, the first determination unit 223a determines whether the destination IP address of the packet acquired by the second acquisition unit 221a matches the information about the communication path acquired by the second acquisition unit 221a.

[0027] Also, for example, the first determination unit 223a determines whether or not the destination IP address of a packet determined by the first determination unit 222a to use GTP-U matches the destination IP address that is the target of heterogeneous network allocation acquired by the second acquisition unit 221a. Also, for example, the first determination unit 223a determines whether or not the destination IP address of a packet determined by the first determination unit 222a to include a QinQ tag matches the destination IP address that is the target of heterogeneous network entry acquired by the second acquisition unit 221a.

[0028] The first rewriting unit 224a rewrites the header of the packet that the first determining unit 223a has determined to be a match, based on the information about the communication path acquired by the second acquiring unit 221a. For example, the first rewriting unit 224a rewrites the source IP address of the packet that the first determining unit 223a has determined to be a match, to the IP address of the PE router that functions as the forwarding device 200.

[0029] Also, for example, the first rewriting unit 224a writes MPLS (Multi Protocol Label Switching) label information, which is information about the route to the router that accommodates the terminal having the destination IP address that is the target of heterogeneous network entry, acquired by the second acquisition unit 221a, into the header of the packet that is determined to match by the first determination unit 223a.

[0030] The creation unit 225 creates information about the communication path based on the information about the communication path acquired by the second acquisition unit 221a and the packet whose header has been rewritten by the first rewriting unit 224a. For example, the creation unit 225 creates information about the communication path based on the information about the communication path acquired by the second acquisition unit 221a and the packet whose source IP address has been changed by the first rewriting unit 224a.

[0031] Also, for example, the creation unit 225 creates information about a communication path including the changed source IP address, the original source IP address, and information about a path to a router that accommodates a terminal that has a destination IP address that is the target of heterogeneous network allocation, based on information about the path to a router that accommodates a terminal that has a destination IP address that is the target of heterogeneous network allocation, which information was acquired by the second acquisition unit 221a, and a packet in which the source IP address has been changed by the first rewriting unit 224a to an IP address held by a PE router that functions as the forwarding device 200.

[0032] The first transmitting unit 227a transmits the packet, whose header has been rewritten by the first rewriting unit 224a, to the first forwarding device 200A or the second forwarding device 200B, which are in a different VPN. For example, the first transmitting unit 227a of the first forwarding device 200A transmits the packet, whose header has been rewritten by the first rewriting unit 224a, to the second forwarding device 200B. Also, for example, the first transmitting unit 227a of the second forwarding device 200B transmits the packet, whose header has been rewritten by the first rewriting unit 224a, to the first forwarding device 200A.

[0033] The third acquisition unit 221b acquires the packets transmitted by the first transmission unit 227a, information about the communication path distributed by the distribution unit 122, and information about the communication path created by the creation unit 225.

[0034] For example, the third acquisition unit 221b acquires information about the communication path, including the packet transmitted by the first transmission unit 227a, information about the IP address pool distributed by the distribution unit 122, information about the destination IP address that is the target of heterogeneous network allocation, information about the route to the router that accommodates the terminal having the destination IP address that is the target of heterogeneous network access, and information about the changed source IP address, the original source IP address, and the route to the router that accommodates the terminal having the destination IP address that is the target of heterogeneous network allocation, created by the creation unit 225. Also, for example, the third acquisition unit 221b acquires information linking the IP address of the mobile terminal with GTP-U tunnel information from communication of the C-Plane as information about the communication path.

[0035] The processing unit 226 processes the header of the packet acquired by the third acquisition unit 221b. For example, the processing unit 226 removes the MPLS label from the header of the packet acquired by the third acquisition unit 221b.

[0036] The second determination unit 222b determines whether a predetermined protocol is used in the packet acquired by the third acquisition unit 221b. For example, the second determination unit 222b determines whether GTP-U is used in the packet acquired by the third acquisition unit 221b. Also, for example, the second determination unit 222b determines whether a QinQ tag is included in the packet acquired by the third acquisition unit 221b. Note that the above is an example, and the predetermined protocol used for determination by the second determination unit 222b is not limited.

[0037] The second determination unit 223b determines whether the destination IP address of the packet acquired by the third acquisition unit 221b matches the information about the communication path acquired by the third acquisition unit 221b. For example, when the second determination unit 222b determines that a predetermined protocol is not used, the second determination unit 223b determines whether the destination IP address of the packet acquired by the third acquisition unit 221b matches the information about the communication path acquired by the third acquisition unit 221b. Also, for example, the second determination unit 223b determines whether the destination IP address of the packet determined by the second determination unit 222b not to contain a QinQ tag matches the destination IP address that is the target of heterogeneous network allocation acquired by the third acquisition unit 221b.

[0038] Also, for example, the second judgment unit 223b judges whether the destination IP address of the packet that has been determined by the second discrimination unit 222b not to use GTP-U matches the destination IP address that is the target of heterogeneous network allocation acquired by the third acquisition unit 221b.

[0039] The second rewriting unit 224b rewrites the header of the packet determined to be a match by the second determination unit 223b based on the information about the communication path acquired by the third acquisition unit 221b. For example, the second rewriting unit 224b rewrites the header of the packet determined to be a match by the second determination unit 223b to a tunnel header suitable for the destination IP address network based on the information about the communication path acquired by the third acquisition unit 221b. As a specific example, if the terminal indicated by the destination IP address is a mobile terminal, the second rewriting unit 224b rewrites the header to a GTP-U tunnel header. Also, for example, if the terminal indicated by the destination IP address is a fixed terminal, the second rewriting unit 224b rewrites the header to a QinQ tunnel header.

[0040] Also, for example, the second rewriting unit 224b rewrites the destination IP address in the header of the packet that is determined to match by the second judgment unit 223b to the IP address of the terminal based on information about the communication path created by the creation unit 225.

[0041] The second transmitter 227b transmits the packet whose header has been rewritten by the second rewriter 224b to a terminal. For example, the second transmitter 227b of the first transfer device 200A transmits the packet whose header has been rewritten by the second rewriter 224b to a fixed terminal or a mobile terminal. Also, for example, the second transmitter 227b of the second transfer device 200B transmits the packet whose header has been rewritten by the second rewriter 224b to a fixed terminal or a mobile terminal.

[0042] (Communication from fixed terminal to mobile terminal) [Preset] 4, the presetting of communication processing by the communication system 1 when communicating from a terminal under a fixed network to a terminal under a mobile network will be described. First, the distribution unit 122 of the distribution device 100 distributes information about the communication path to the first transfer device 200A located on the fixed terminal side and the second transfer device 200B located on the mobile terminal side. For example, the distribution unit 122 distributes, to the first transfer device 200A and the second transfer device 200B, the destination IP address that is the target of heterogeneous network entry and MPLS label information as route information to the opposing PE router (the first transfer device 200A or the second transfer device 200B) that accommodates the terminal having the IP address.

[0043] Next, the first transfer device 200A and the second transfer device 200B to which the information regarding the communication path has been distributed create a table including information regarding the IP addresses and header rewriting that are the targets of heterogeneous network access.

[0044] At this time, the second acquisition unit 221a or the third acquisition unit 221b of the second transfer device 200B that accommodates the mobile terminal acquires information linking the IP address of the mobile terminal with GTP-U tunnel information as information related to the communication path from the C-Plane communication, and creates a table. Note that the process of creating a table by the second transfer device 200B that includes information linking the terminal IP address with GTP-U tunnel information is performed every time a session is changed.

[0045] [Communication processing] Next, using Figure 5, we will explain the communication processing by the communication system 1 when communicating from a terminal under a fixed network to a terminal under a mobile network. After completing the pre-configuration described in Figure 4, the first transfer device 200A determines whether the packet is a target for transfer. At this time, for example, the first determination unit 222a of the first transfer device 200A determines that QinQ is being used. Also, for example, the first determination unit 223a of the first transfer device 200A determines whether the packet is a target for heterogeneous network transfer by comparing the destination IP address of the packet transmitted from the fixed terminal with a table containing information about the communication route acquired in the pre-configuration.

[0046] Then, the first rewriting unit 224a of the first forwarding device 200A rewrites the header of the packet if the packet is to be entered. For example, the first rewriting unit 224a of the first forwarding device 200A rewrites the source IP address of the packet to be entered to the IP address of the first forwarding device 200A. At this time, the creation unit 225 of the first forwarding device 200A creates information about the communication path including the post-NAT assigned IP address, the fixed terminal IP address (source IP address), and S / C-tag information corresponding to the destination IP address. In addition, the first rewriting unit 224a of the first forwarding device 200A assigns an MPLS label to the packet to be entered. Then, the first transmitting unit 227a of the first forwarding device 200A transmits the rewritten packet to the second forwarding device 200B.

[0047] Next, the second transfer device 200B analyzes the transmitted packet. At this time, for example, the second determination unit 222b possessed by the second transfer device 200B determines whether or not GTP-U is used in the transmitted packet. Then, if GTP-U is not used, the second rewriting unit 224b possessed by the second transfer device 200B rewrites the header using information that links the IP address of the mobile terminal with the GTP information. Then, the second transmitting unit 227b possessed by the second transfer device 200B transmits the packet to the mobile terminal using the GTP information.

[0048] Next is the return path. The second acquisition unit 221a of the second forwarding device 200B acquires a packet as a response from the mobile terminal. Then, the first rewriting unit 224a of the second forwarding device 200B rewrites the header if the packet is to be entered. For example, the first rewriting unit 224a of the second forwarding device 200B assigns an MPLS label to the packet to be entered. Then, the first sending unit 227a of the second forwarding device 200B transmits the packet with the MPLS label assigned to the first forwarding device 200A.

[0049] The first transfer device 200A then acquires the packet transmitted from the second transfer device 200B and performs packet analysis. If a specific protocol is not used in the packet (for example, QinQ), the second rewriting unit 224b of the first transfer device 200A rewrites the header using information that links the fixed terminal IP address with the QinQ information. The second transmitting unit 227b of the first transfer device 200A then transmits the packet with the rewritten header to the fixed terminal.

[0050] [Preset] Next, the processing explained in Fig. 4 will be explained with reference to Fig. 6, focusing on IP addresses and table information. Fig. 6 is a diagram for explaining presettings when communication is performed from a terminal under a fixed network to a terminal under a mobile network.

[0051] 6(1) shows pre-setting performed by distributing information about communication paths from the distribution device 100 to the first transfer device 200A and the second transfer device 200B. For example, the distribution device 100 distributes information about a destination IP address that is a target of heterogeneous network entry and information about an MPLS label that corresponds to the destination IP address to the first transfer device 200A. Also, for example, the distribution device 100 distributes information about a destination IP address that is a target of heterogeneous network entry, information about an MPLS label that corresponds to the destination IP address, and information about GTP to the second transfer device 200B.

[0052] Next, FIG. 6(2) shows the pre-setting performed by acquiring GTP tunnel information using the mobile terminal IP address as a key when the power of the terminal device that is the target of heterogeneous network entry on the mobile terminal side is turned on. For example, the second transfer device 200B acquires the fixed IP address and GTP information of the mobile terminal by connecting and registering with 5GC (5G Core). At this time, for example, the fixed IP address and GTP information of the mobile terminal are acquired using the method described in Patent Document 1.

[0053] [Communication processing] 5 will be explained with reference to FIG. 7, focusing on IP addresses and table information. FIG. 7(1) shows the flow of communication from a fixed terminal to a mobile terminal. First, the fixed terminal transmits a packet whose source IP address is the fixed terminal and whose destination IP address is the mobile terminal. Next, the first rewriting unit 224a of the first forwarding device 200A that receives the packet uses a table containing information on the destination IP address and the MPLS label corresponding to the destination IP address to assign MPLS label information and rewrite the header so that the source IP address becomes the IP address of the first forwarding device 200A.

[0054] At this time, the creation unit 225 of the first transfer device 200A creates a table including information on the assigned IP address after NAT for address conversion, the fixed terminal IP address, and the S / C-tag corresponding to the destination IP address. Then, the first transmission unit 227a of the first transfer device 200A transmits the rewritten packet to the second transfer device 200B.

[0055] Next, the second rewriting unit 224b of the second transfer device 200B that receives the packet transmitted from the first transfer device 200A uses a table containing the IP address of the mobile terminal and GTP information to rewrite the packet header and encap the GTP. Then, the second transmitting unit 227b of the second transfer device 200B transmits the packet to the mobile terminal.

[0056] Next, Figure 7 (2) shows a response from the mobile terminal to the fixed terminal. The mobile terminal transmits a packet whose source IP address is the mobile terminal and whose destination IP address is the first forwarding device 200A. Next, the first rewriting unit 224a of the second forwarding device 200B that receives the packet uses a table containing the destination IP address and MPLS label information corresponding to the destination IP address to rewrite the packet header and assign an MPLS label. The second forwarding device 200B then transmits the rewritten packet to the first forwarding device 200A.

[0057] Next, the second rewriting unit 224b of the first transfer device 200A that receives the packet transmitted from the second transfer device 200B uses a table containing the assigned IP address after NAT, the fixed terminal IP address, and information on the S / C-tag corresponding to the destination IP address to change the destination IP address to the IP address of the fixed terminal. At this time, the second rewriting unit 224b of the first transfer device 200A rewrites the packet header and performs QinQ encap. Then, the second transmitting unit 227b of the first transfer device 200A transmits the packet to the fixed terminal.

[0058] (Communication from mobile terminal to fixed terminal) Up to this point, we have explained the case of communication from a fixed terminal to a mobile terminal using Figures 4 to 7, but from here on, we will explain the case of communication from a mobile terminal to a fixed terminal. Note that, due to the nature of the information to be acquired, it is appropriate for GTP encap to be processed by the transfer device 200 present on the mobile terminal side, but for example, QinQ encap can be processed by either the transfer device 200 present on the mobile terminal side or the transfer device 200 present on the fixed terminal side.

[0059] Therefore, when communicating from a mobile terminal to a fixed terminal, as an example, we will explain a pattern in which QinQ encap is performed by the transfer device 200 on the mobile terminal side and a pattern in which it is performed by the transfer device 200 on the fixed terminal side.

[0060] [Preset] 8, the presetting of communication processing by the communication system 1 when communicating from a terminal under a mobile network to a terminal under a fixed network will be described. As an example, a pattern is shown in which QinQ encap is performed by the transfer device 200 on the mobile terminal side. First, the distribution unit 122 of the distribution device 100 distributes information about communication paths to the first transfer device 200A present on the mobile terminal side and the second transfer device 200B present on the fixed terminal side.

[0061] For example, the destination IP address to be accessed through a heterogeneous network, MPLS label information as route information to the opposing PE router (the first forwarding device 200A or the second forwarding device 200B) that accommodates the terminal having that IP address, and S / C-tag information corresponding to the destination IP address are distributed to the first forwarding device 200A and the second forwarding device 200B. In this pattern, the S / C-tag information is issued from the distribution device 100 to the first forwarding device 200A located on the mobile terminal side, thereby enabling QinQ encap by the first forwarding device 200A located on the mobile terminal side.

[0062] Next, the first transfer device 200A and the second transfer device 200B to which the information regarding the communication path has been distributed create a table including information regarding the IP addresses and header rewriting that are the targets of heterogeneous network access.

[0063] At this time, the second acquisition unit 221a or the third acquisition unit 221b of the first transfer device 200A that accommodates the mobile terminal acquires information linking the IP address of the mobile terminal with GTP-U tunnel information as information related to the communication path from the C-Plane communication, and creates a table. Note that the process of creating a table by the first transfer device 200A that includes information linking the terminal IP address with GTP-U tunnel information is performed every time a session is changed.

[0064] [Communication processing] Next, using Figure 9, we will explain the communication processing by the communication system 1 when communicating from a terminal under a mobile network to a terminal under a fixed network. After completing the pre-configuration described in Figure 8, the first transfer device 200A determines whether the packet is a target for transfer. At this time, for example, the first determination unit 222a of the first transfer device 200A determines that GTP-U is used. Also, for example, the first determination unit 223a of the first transfer device 200A determines whether the packet is a target for heterogeneous network transfer by comparing the destination IP address of the packet transmitted from the mobile terminal with a table containing information about the communication route acquired in the pre-configuration.

[0065] Then, the first rewriting unit 224a of the first transfer device 200A rewrites the header of the packet if it is a packet to be entered. For example, the first rewriting unit 224a of the first transfer device 200A rewrites the source IP address of the packet to be entered to the IP address of the first transfer device 200A.

[0066] At this time, the creation unit 225 of the first forwarding device 200A creates a table including information on the assigned IP addresses after NAT for address conversion and the mobile terminal IP addresses. In addition, the first rewriting unit 224a of the first forwarding device 200A assigns MPLS labels to packets to be entered and encaps QinQ.

[0067] Then, the first transmitting unit 227a of the first transfer device 200A transmits the rewritten packet to the second transfer device 200B. The second transfer device 200B, which receives the packet, performs processing as usual.

[0068] Next is the return path. First, the second acquisition unit 221a of the second forwarding device 200B acquires a packet as a response from the fixed terminal. Next, the first rewriting unit 224a of the second forwarding device 200B rewrites the header if the packet is subject to entry determination. For example, the first rewriting unit 224a of the second forwarding device 200B assigns an MPLS label to the packet to be entered. Then, the first transmitting unit 227a of the second forwarding device 200B transmits the packet with the MPLS label assigned to the first forwarding device 200A.

[0069] Next, the first transfer device 200A acquires the packet transmitted from the second transfer device 200B and performs packet analysis. If a predetermined protocol is not used in the packet (for example, GTP-U), the second rewriting unit 224b of the first transfer device 200A rewrites the header using information that links the mobile terminal IP address with GTP information. Then, the second transmitting unit 227b of the first transfer device 200A transmits the packet with the rewritten header to the mobile terminal.

[0070] [Preset] Next, the processing explained in Fig. 8 will be explained with reference to Fig. 10, focusing on IP addresses and table information. Fig. 10 is a diagram for explaining presettings when communication is performed from a terminal under a mobile network to a terminal under a fixed network.

[0071] 10(1) shows pre-setting performed by distributing information about communication paths from the distribution device 100 to the first transfer device 200A and the second transfer device 200B. For example, the distribution device 100 distributes, to the first transfer device 200A, information about a destination IP address that is a target of heterogeneous network entry, information about an MPLS label corresponding to the destination IP address, and S / C-tag information corresponding to the destination IP address. Also, for example, the distribution device 100 distributes, to the second transfer device 200B, information about a destination IP address that is a target of heterogeneous network entry and information about an MPLS label corresponding to the destination IP address.

[0072] Next, FIG. 10(2) shows the pre-setting performed by acquiring GTP tunnel information using the mobile terminal IP address as a key when the power of the terminal device that is the target of heterogeneous network access on the mobile terminal side is turned on. For example, the first transfer device 200A acquires the fixed IP address and GTP information of the mobile terminal by connecting and registering with 5GC (5G Core). At this time, for example, the fixed IP address and GTP information of the mobile terminal are acquired using the method described in Patent Document 1.

[0073] [Communication processing] 9 will be explained with reference to FIG. 11, focusing on IP addresses and table information. FIG. 11(1) shows the flow of communication from a mobile terminal to a fixed terminal. First, the mobile terminal transmits a packet whose source IP address is the mobile terminal and whose destination IP address is the fixed terminal. Next, the first rewriting unit 224a of the first forwarding device 200A that receives the packet uses a table containing the destination IP address, the MPLS label corresponding to the destination IP address, and the S / C-tag information corresponding to the destination IP address to add MPLS label information, encap QinQ, and rewrite the header so that the source IP address becomes the IP address of the first forwarding device 200A.

[0074] At this time, the creation unit 225 of the first transfer device 200A creates a table including the assigned IP addresses after NAT for address conversion and the mobile terminal IP addresses. Then, the first transmission unit 227a of the first transfer device 200A transmits the rewritten packet to the second transfer device 200B. Then, the second transmission unit 227b of the second transfer device 200B, which receives the packet transmitted from the first transfer device 200A, transmits the packet to the fixed terminal.

[0075] Next is the return path. Figure 11 (2) shows a response from a fixed terminal to a mobile terminal. The fixed terminal transmits a packet whose source IP address is the fixed terminal and whose destination IP address is the first forwarding device 200A. Next, the first rewriting unit 224a of the second forwarding device 200B that receives the packet uses a table containing the destination IP address and the MPLS label information corresponding to the destination IP address to rewrite the packet header and assign an MPLS label. Then, the first transmitting unit 227a of the second forwarding device 200B transmits the rewritten packet to the first forwarding device 200A.

[0076] Next, the second rewriting unit 224b of the first transfer device 200A that receives the packet transmitted from the second transfer device 200B uses a table containing information on the assigned IP address after NAT and the mobile terminal IP address to change the destination IP address to the IP address of the mobile terminal. At this time, the second rewriting unit 224b of the first transfer device 200A uses a table containing the mobile terminal IP address and GTP information to rewrite the packet header and encap the GTP. Then, the second transmitting unit 227b of the first transfer device 200A transmits the packet to the mobile terminal.

[0077] (Communication from mobile terminal to fixed terminal) [Preset] 12, the presetting of communication processing by the communication system 1 when communicating from a terminal under a mobile network to a terminal under a fixed network will be described. As an example, a pattern is shown in which QinQ encap is performed by the transfer device 200 located on the fixed terminal side. First, the distribution unit 122 of the distribution device 100 distributes information about the communication path to the first transfer device 200A located on the mobile terminal side and the second transfer device 200B located on the fixed terminal side.

[0078] For example, the destination IP address to be entered into the heterogeneous network, MPLS label information as route information to the opposing PE router (the first forwarding device 200A or the second forwarding device 200B) that accommodates the terminal having that IP address, and S / C-tag information corresponding to the destination IP address are distributed to the first forwarding device 200A and the second forwarding device 200B. In this pattern, the S / C-tag information is issued from the distribution device 100 to the second forwarding device 200B located on the fixed terminal side, thereby enabling QinQ encap by the second forwarding device 200B located on the fixed terminal side.

[0079] Next, the first transfer device 200A and the second transfer device 200B to which the information regarding the communication path has been distributed create a table including information regarding the IP addresses and header rewriting that are the targets of heterogeneous network access.

[0080] At this time, the second acquisition unit 221a or the third acquisition unit 221b of the first transfer device 200A that accommodates the mobile terminal acquires information linking the IP address of the mobile terminal with GTP-U tunnel information as information related to the communication path from the C-Plane communication, and creates a table. Note that the process of creating a table by the first transfer device 200A that includes information linking the terminal IP address with GTP-U tunnel information is performed every time a session is changed.

[0081] [Communication processing] Next, using Figure 13, we will explain the communication processing by the communication system 1 when communicating from a terminal under a fixed network to a terminal under a mobile network. After completing the pre-configuration described in Figure 12, the first transfer device 200A determines whether the packet is a target for transfer. At this time, for example, the first determination unit 222a of the first transfer device 200A determines that GTP-U is used. Also, for example, the first determination unit 223a of the first transfer device 200A determines whether the packet is a target for heterogeneous network transfer by comparing the destination IP address of the packet transmitted from the mobile terminal with a table containing information about the communication route acquired in the pre-configuration.

[0082] Then, the first rewriting unit 224a of the first transfer device 200A rewrites the header of the packet if the packet is to be entered. For example, the first rewriting unit 224a of the first transfer device 200A rewrites the source IP address of the packet to be entered to the IP address of the first transfer device 200A.

[0083] At this time, the creation unit 225 of the first forwarding device 200A creates a table including information on the assigned IP addresses after NAT for address conversion and the mobile terminal IP addresses. Then, the first rewriting unit 224a of the first forwarding device 200A assigns an MPLS label to the packet to be entered.

[0084] Then, the first transmitting unit 227a of the first transfer device 200A transmits the rewritten packet to the second transfer device 200B. The second determining unit 222b of the second transfer device 200B that receives the packet determines whether or not QinQ is used in the transmitted packet. Then, if QinQ is not used, the second rewriting unit 224b of the second transfer device 200B rewrites the header using information that links the IP address of the mobile terminal with the QinQ information. Then, the second transmitting unit 227b of the second transfer device 200B transmits the packet to the fixed terminal using the QinQ information.

[0085] Next is the return path. First, the second acquisition unit 221a of the second forwarding device 200B acquires a packet as a response from the fixed terminal. Next, the first rewriting unit 224a of the second forwarding device 200B rewrites the header if the packet is subject to entry determination. For example, the first rewriting unit 224a of the second forwarding device 200B assigns an MPLS label to the packet to be entered. Then, the first transmitting unit 227a of the second forwarding device 200B transmits the packet with the MPLS label assigned to the first forwarding device 200A.

[0086] Next, the first transfer device 200A acquires the packet transmitted from the second transfer device 200B and performs packet analysis. If a predetermined protocol is not used in the packet (for example, GTP-U), the second rewriting unit 224b of the first transfer device 200A rewrites the header using information that links the mobile terminal IP address with GTP information. Then, the second transmitting unit 227b of the first transfer device 200A transmits the packet with the rewritten header to the mobile terminal.

[0087] [Preset] Next, the processing explained in Fig. 12 will be explained with reference to Fig. 14, focusing on IP addresses and table information. Fig. 14 is a diagram for explaining presettings when communication is performed from a terminal under a mobile network to a terminal under a fixed network.

[0088] 14(1) shows pre-setting performed by distributing information about communication paths from the distribution device 100 to the first transfer device 200A and the second transfer device 200B. For example, the distribution device 100 distributes information about a destination IP address that is a target of heterogeneous network entry and information about an MPLS label corresponding to the destination IP address to the first transfer device 200A. Also, for example, the distribution device 100 distributes information about a destination IP address that is a target of heterogeneous network entry, information about an MPLS label corresponding to the destination IP address, and S / C-tag information corresponding to the destination IP address to the second transfer device 200B.

[0089] Next, FIG. 14(2) shows the pre-setting performed by acquiring GTP tunnel information using the mobile terminal IP address as a key when the power of the terminal device that is the target of heterogeneous network entry on the mobile terminal side is turned on. For example, the first transfer device 200A acquires the fixed IP address and GTP information of the mobile terminal by connecting and registering with 5GC. At this time, for example, the fixed IP address and GTP information of the mobile terminal are acquired using the method described in Patent Document 1.

[0090] [Communication processing] Using Figure 15, the processing described in Figure 13 will be explained, focusing on IP addresses and table information. Figure 15(1) shows the flow of communication from a mobile terminal to a fixed terminal. First, the mobile terminal sends a packet whose source IP address is the mobile terminal and whose destination IP address is the fixed terminal. Next, the first rewriting unit 224a of the first forwarding device 200A that receives the packet uses a table containing destination IP addresses and MPLS labels corresponding to the destination IP addresses to assign MPLS label information and rewrite the header so that the source IP address becomes the IP address of the first forwarding device 200A.

[0091] At this time, the creation unit 225 of the first transfer device 200A creates a table including the assigned IP addresses after NAT for address conversion and the mobile terminal IP addresses. Then, the first transmission unit 227a of the first transfer device 200A transmits the rewritten packet to the second transfer device 200B. Then, the second rewriting unit 224b of the second transfer device 200B, which receives the packet transmitted from the first transfer device 200A, rewrites the header using a table including the destination IP addresses and S / C-tag information corresponding to the destination IP addresses. The second transmission unit 227b of the second transfer device 200B transmits the rewritten packet to the fixed terminal.

[0092] Next is the return path. Figure 15 (2) shows a response from a fixed terminal to a mobile terminal. The fixed terminal transmits a packet whose source IP address is the fixed terminal and whose destination IP address is the first forwarding device 200A. Next, the first rewriting unit 224a of the second forwarding device 200B that receives the packet uses a table containing the destination IP address and the MPLS label information corresponding to the destination IP address to rewrite the packet header and assign an MPLS label. Then, the first transmitting unit 227a of the second forwarding device 200B transmits the rewritten packet to the first forwarding device 200A.

[0093] Next, the second rewriting unit 224b of the first transfer device 200A that receives the packet transmitted from the second transfer device 200B uses a table containing information on the assigned IP address after NAT and the mobile terminal IP address to change the destination IP address to the IP address of the mobile terminal. Also, the second rewriting unit 224b of the first transfer device 200A uses a table containing the mobile terminal IP address and GTP information to rewrite the packet header and encap the GTP. Then, the second transmitting unit 227b of the first transfer device 200A transmits the packet to the mobile terminal.

[0094] FIG. 16 is a diagram summarizing information about a table used when the transfer device 200 exists on the fixed terminal side and a table used when the transfer device 200 exists on the mobile terminal side.

[0095] [flowchart] Next, the flow of processing by transfer device 200 will be described with reference to Figures 17 and 18. First, Figure 17 describes the flow when transfer device 200 acquires a packet from a port located on the terminal side. Note that steps S101 to S108 below can also be executed in a different order. Also, some processing of steps S101 to S108 below may be omitted.

[0096] (Communication from the terminal port) First, the second acquisition unit 221a acquires a packet and information about the communication path distributed by the distribution unit 122 (S101). For example, the second acquisition unit 221a acquires, as the information about the communication path distributed by the distribution unit 122, information about an IP address pool, information about a destination IP address that is a target of heterogeneous network allocation, and information about a path to a router that accommodates a terminal having a destination IP address that is a target of heterogeneous network allocation.

[0097] Next, the first determination unit 222a determines whether a predetermined protocol is used in the packet acquired by the second acquisition unit 221a (S102). For example, the first determination unit 222a determines whether GTP-U is used in the packet acquired by the second acquisition unit 221a. Also, for example, the first determination unit 222a determines whether a QinQ tag is included in the packet acquired by the second acquisition unit 221a.

[0098] Then, if the first determination unit 222a determines that a predetermined protocol is used (S102 "YES"), the first determination unit 223a determines whether or not there is information on a communication path that is a return path and that matches the destination IP address (S103). For example, the first determination unit 223a determines whether or not the destination IP address of the packet that is determined by the first determination unit 222a to be a return path and that uses GTP-U matches the destination IP address that is the target of heterogeneous network transfer and that is acquired by the second acquisition unit 221a.

[0099] Here, if the first determination unit 223a determines that there is no information about a communication path that is a return path and that matches the destination IP address (S103 "NO"), then the first determination unit 223a determines whether there is information about a communication path that is an outbound path and that matches the destination IP address of the packet acquired by the second acquisition unit 221a (S104). For example, the first determination unit 223a determines whether the destination IP address of the packet that is an outbound path and that is determined by the first determination unit 222a to use GTP-U matches the destination IP address that is the target of heterogeneous network transfer acquired by the second acquisition unit 221a.

[0100] Here, if the first determination unit 223a determines that there is information about a communication path that is an outbound path and matches the destination IP address (S104 "YES"), the first rewriting unit 224a changes the source IP address of the packet that the first determination unit 223a determines to match (S105). For example, the first rewriting unit 224a changes the source IP address of the packet that the first determination unit 223a determines to match to the IP address of the PE router functioning as the forwarding device 200.

[0101] Next, the creation unit 225 creates information about the communication path based on the information about the communication path acquired by the second acquisition unit 221a and the packet whose header has been rewritten by the first rewriting unit 224a (S106). For example, based on information about the path to a router accommodating a terminal having a destination IP address that is the target of heterogeneous network allocation acquired by the second acquisition unit 221a and the packet whose source IP address has been changed by the first rewriting unit 224a to the IP address of the PE router functioning as the forwarding device 200, the creation unit 225 creates information about the communication path including the changed source IP address, the original source IP address, and information about the path to a router accommodating a terminal having a destination IP address that is the target of heterogeneous network transfer.

[0102] Subsequently, or when the first determination unit 223a determines that there is information on a communication route that is a return route and matches the destination IP address (S103 "YES"), the first rewriting unit 224a rewrites the header of the packet that the first determination unit 223a determined to match based on the information on the communication route acquired by the second acquisition unit 221a (S107). For example, the first rewriting unit 224a writes MPLS label information, which is information on the route to a router that accommodates a terminal having a destination IP address that is the target of heterogeneous network allocation acquired by the second acquisition unit 221a, into the header of the packet that the first determination unit 223a determined to match.

[0103] Then, the first transmitting unit 227a transmits the packet whose header has been rewritten by the first rewriting unit 224a to the first transfer device 200A or the second transfer device 200B that exists in a different VPN (S108).

[0104] Furthermore, if the first determination unit 222a determines that a specified protocol is not being used (S102 "NO"), or if the first determination unit 223a determines that there is no information about a communication path that is the outbound path and matches the destination IP address (S104 "NO"), processing by the transfer device 200 ends.

[0105] (Communication from core network port) Next, a flow when a packet is acquired from a port on the core network side will be described with reference to Fig. 18. Note that the following steps S201 to S206 may be executed in a different order. Also, some of the following steps S201 to S206 may be omitted.

[0106] First, the third acquisition unit 221b acquires the packet transmitted by the first transmission unit 227a, information on the communication path distributed by the distribution unit 122, and information on the communication path created by the creation unit 225 (S201). For example, the third acquisition unit 221b acquires the packet transmitted by the first transmission unit 227a, information on the IP address pool, information on the destination IP address to be subject to heterogeneous network allocation, and information on the path to the router accommodating the terminal having the destination IP address to be subject to heterogeneous network allocation, all of which are distributed by the distribution unit 122.

[0107] Next, the processing unit 226 processes the header of the packet acquired by the third acquisition unit 221b (S202). For example, the processing unit 226 removes the MPLS label from the header of the packet acquired by the third acquisition unit 221b.

[0108] Then, the second determination unit 222b determines whether a predetermined protocol is used in the packet acquired by the third acquisition unit 221b (S203). For example, the second determination unit 222b determines whether GTP-U is used in the packet acquired by the third acquisition unit 221b. Also, for example, the second determination unit 222b determines whether a QinQ tag is included in the packet acquired by the third acquisition unit 221b.

[0109] Next, if the second determination unit 222b determines that the packet does not contain a predetermined protocol (S203 "NO"), the second determination unit 223b determines whether the destination IP address of the packet acquired by the third acquisition unit 221b matches the information on the communication path acquired by the third acquisition unit 221b (S204). For example, the second determination unit 223b determines whether the destination IP address of the packet determined by the second determination unit 222b not to contain a QinQ tag matches the destination IP address that is the target of heterogeneous network allocation acquired by the third acquisition unit 221b.

[0110] If the second determination unit 223b determines that there is a match (S204 "YES"), the second rewriting unit 224b causes the third acquisition unit 221b to rewrite the header of the packet based on the information about the communication route acquired by the third acquisition unit 221b (S205). For example, the second rewriting unit 224b rewrites the header of the packet determined to be a match by the second determination unit 223b to a tunnel header suitable for the destination IP address network based on the information about the communication route acquired by the third acquisition unit 221b.

[0111] Then, the second transmitting unit 227b transmits the packet whose header has been rewritten by the second rewriting unit 224b to the terminal (S206). For example, the second transmitting unit 227b of the first transfer device 200A transmits the packet whose header has been rewritten by the second rewriting unit 224b to a fixed terminal or a mobile terminal. Also, for example, the second transmitting unit 227b of the second transfer device 200B transmits the packet whose header has been rewritten by the second rewriting unit 224b to a fixed terminal or a mobile terminal.

[0112] [effect] The communication system 1 according to the embodiment includes a distribution device 100, a first transfer device 200A, and a second transfer device 200B. The distribution device 100 includes a first acquisition unit 121 that acquires information about a communication path, and a distribution unit 122 that transmits the information about the communication path acquired by the first acquisition unit 121 to the first transfer device 200A and the second transfer device 200B. The first transfer device 200A and the second transfer device 200B include a second acquisition unit 221a that acquires packets and the information about the communication path distributed by the distribution unit 122, and a destination I of the packet acquired by the second acquisition unit 221a. The VPN server 200 includes a first determination unit 223a that determines whether the P address matches the information about the communication path acquired by the second acquisition unit 221a, a first rewriting unit 224a that rewrites the header of the packet acquired by the second acquisition unit 221a based on the information about the communication path acquired by the second acquisition unit 221a when the first determination unit 223a determines that there is a match, and a first transmission unit 227a that transmits the packet whose header has been rewritten by the first rewriting unit 224a to the first transfer device 200A or the second transfer device 200B that exists in a different VPN.

[0113] This enables the communication system 1 to transmit packets to the opposing PE router via the access network without passing through the core network / Internet network.

[0114] Furthermore, the first transfer device 200A and the second transfer device 200B included in the communication system 1 according to the embodiment include a creation unit 225 that creates information about the communication path based on information about the communication path acquired by the second acquisition unit 221a and a packet whose header has been rewritten by the first rewriting unit 224a, a third acquisition unit 221b that acquires the packet transmitted by the first transmission unit 227a, the information about the communication path distributed by the distribution unit 122, and the information about the communication path created by the creation unit 225, and a processing unit 221c that processes the header of the packet acquired by the third acquisition unit 221b. The packet transmission device further includes a processing unit 226, a second determination unit 223b that determines whether the destination IP address of the packet acquired by the third acquisition unit 221b matches the information about the communication route acquired by the third acquisition unit 221b, a second rewriting unit 224b that rewrites the header of the packet acquired by the third acquisition unit 221b based on the information about the communication route acquired by the third acquisition unit 221b when the second determination unit 223b determines that there is a match, and a second transmission unit 227b that transmits the packet whose header has been rewritten by the second rewriting unit 224b to the terminal.

[0115] As a result, the communication system 1 transmits packets to the destination terminal via the access network without passing through the core network / Internet network, thereby reducing delays.

[0116] Furthermore, the first transfer device 200A and the second transfer device 200B included in the communication system 1 according to the embodiment further include a first determination unit 222a that determines whether a predetermined protocol is used in a packet acquired by the second acquisition unit 221a, and a second determination unit 222b that determines whether a predetermined protocol is used in a packet acquired by the third acquisition unit 221b. When the first determination unit 222a determines that a predetermined protocol is used, the first determination unit 223a determines whether a destination IP address of the packet acquired by the second acquisition unit 221a matches information about the communication path acquired by the second acquisition unit 221a, and when the second determination unit 222b determines that a predetermined protocol is not used, the second determination unit 223b determines whether a destination IP address of the packet acquired by the third acquisition unit 221b matches information about the communication path acquired by the third acquisition unit 221b.

[0117] As a result, the communication system 1 determines whether a predetermined protocol is present and performs encap / decap, thereby eliminating protocol differences, thereby reducing delays and improving closed-area functionality.

[0118] The second acquisition unit 221a or the third acquisition unit 221b acquires information linking the IP address of the mobile terminal with the GTP-U tunnel information as information relating to the communication path.

[0119] This allows the communication system 1 to obtain the fixed IP address of the mobile terminal and information on the protocol used in communication with that IP address, and to rewrite the header in accordance with the communication protocol of the mobile terminal.

[0120] [program] It is also possible to create a program in which the processes executed by the communication system 1 described in the above embodiment are written in a language executable by a computer. In this case, the same effects as those of the above embodiment can be obtained by having a computer execute the program. Furthermore, such a program may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by a computer to realize the same processes as those of the above embodiment.

[0121] 19 is a diagram showing a computer that executes a program. As shown in the example of FIG. 19, a computer 1000 includes, for example, a memory 1010, a CPU 1020, a hard disk drive interface 1030, a disk drive interface 1040, a serial port interface 1050, a video adapter 1060, and a network interface 1070, and these components are connected by a bus 1080.

[0122] 19, the memory 1010 includes a ROM (Read Only Memory) 1011 and a RAM 1012. The ROM 1011 stores a boot program such as a BIOS (Basic Input Output System). The hard disk drive interface 1030 is connected to a hard disk drive 1090 as shown in FIG.

[0123] The disk drive interface 1040 is connected to a disk drive 1100, as shown in Fig. 19. For example, a removable storage medium such as a magnetic disk or optical disk is inserted into the disk drive 1100. The serial port interface 1050 is connected to, for example, a mouse 1110 and a keyboard 1120, as shown in Fig. 19. The video adapter 1060 is connected to, for example, a display 1130, as shown in Fig. 19.

[0124] 19, the hard disk drive 1090 stores, for example, an OS 1091, an application program 1092, a program module 1093, and program data 1094. That is, the above programs are stored, for example, on the hard disk drive 1090 as program modules in which instructions to be executed by the computer 1000 are written.

[0125] The various data described in the above embodiment are stored as program data, for example, in the memory 1010 or the hard disk drive 1090. The CPU 1020 then reads the program module 1093 and the program data 1094 stored in the memory 1010 or the hard disk drive 1090 into the RAM 1012 as needed, and executes various processing procedures.

[0126] Note that the program module 1093 and program data 1094 related to the program are not limited to being stored in the hard disk drive 1090, and may be stored in, for example, a removable storage medium and read by the CPU 1020 via a disk drive or the like. Alternatively, the program module 1093 and program data 1094 related to the program may be stored in another computer connected via a network (such as a LAN (Local Area Network) or WAN (Wide Area Network)) and read by the CPU 1020 via the network interface 1070.

[0127] [others] Although various embodiments have been described in detail herein with reference to the drawings, these embodiments are merely examples and are not intended to limit the present invention. The features described herein can be realized in various ways, including various modifications and improvements based on the knowledge of those skilled in the art.

[0128] Furthermore, the above-mentioned "module (-er suffix, -or suffix)" can be read as a unit, means, circuit, etc. For example, a communication module, a control module, and a storage module can be read as a communication unit, a control unit, and a storage unit, respectively. [Explanation of symbols]

[0129] 1. Communication Systems 100 Distribution Device 110 Communications Department 120 control section 121 First Acquisition Section 122 Distribution Department 130 Storage section 200A First Transfer Device 200B Second Transfer Device 210 Communications Department 220 Control Unit 221a Second Acquisition Section 221b Third Acquisition Section 222a First Discrimination Section 222b Second Discrimination Section 223a First Judgment Section 223b Second Judgment Section 224a First Rewrite 224b Second Rewrite 225 Creation Department 226 Processing Section 227a First transmitter 227b Second transmitter 230 Storage section

Claims

1. A communication system comprising a distribution device, a first transfer device, and a second transfer device, wherein the first transfer device and the second transfer device exist in different VPNs, The distribution device a first acquisition unit that acquires information about a communication path including information about an IP address pool, information about a destination IP address to be distributed to a heterogeneous network, and information about a path to a transfer device that accommodates a terminal having a destination IP address to be distributed to the heterogeneous network; a distribution unit that distributes information about the communication path acquired by the first acquisition unit to the first transfer device and the second transfer device; and The first transfer device and the second transfer device a second acquisition unit that acquires packets and information about the communication path distributed by the distribution unit; a first determination unit that determines whether or not the destination IP address of the packet acquired by the second acquisition unit matches information about the communication path acquired by the second acquisition unit; a first rewriting unit that rewrites a header of the packet acquired by the second acquisition unit based on information about the communication path acquired by the second acquisition unit when the first determination unit determines that there is a match; a first transmission unit that transmits the packet whose header has been rewritten by the first rewriting unit to the first forwarding device or the second forwarding device that exists in a different VPN; A communication system comprising:

2. The first transfer device and the second transfer device a creating unit that creates information about the communication path based on the information about the communication path acquired by the second acquiring unit and the packet whose header has been rewritten by the first rewriting unit; a third acquisition unit that acquires the packet transmitted by the first transmission unit, information about the communication path distributed by the distribution unit, and information about the communication path created by the creation unit; a processing unit that processes the header of the packet acquired by the third acquisition unit; a second determination unit that determines whether or not the destination IP address of the packet acquired by the third acquisition unit matches information about the communication path acquired by the third acquisition unit; a second rewriting unit that rewrites the header of the packet acquired by the third acquisition unit based on information about the communication path acquired by the third acquisition unit when the second determination unit determines that there is a match; a second transmitting unit that transmits the packet, the header of which has been rewritten by the second rewriting unit, to a terminal; 2. The communication system of claim 1, further comprising:

3. a first determination unit that determines whether a predetermined protocol is used in the packet acquired by the second acquisition unit; a second determination unit that determines whether a predetermined protocol is used in the packet acquired by the third acquisition unit; and the first determination unit, when it is determined by the first determination unit that a predetermined protocol is used, determines whether or not a destination IP address of the packet acquired by the second acquisition unit matches information about the communication path acquired by the second acquisition unit; When the second determination unit determines that a predetermined protocol is not used, the second determination unit determines whether or not the destination IP address of the packet acquired by the third acquisition unit matches the information about the communication path acquired by the third acquisition unit.

3. The communication system according to claim 2.

4. The communication system described in claim 2, characterized in that the second acquisition unit or the third acquisition unit acquires information linking the IP address of a mobile terminal with GTP-U tunnel information as information regarding the communication path.

5. A communication method executed by a communication system including a distribution device, a first transfer device, and a second transfer device, wherein the first transfer device and the second transfer device are in different VPNs, a first acquisition step in which the distribution device acquires information about a communication path including information about an IP address pool, information about a destination IP address to be distributed to a heterogeneous network, and information about a path to a transfer device that accommodates a terminal having a destination IP address to be distributed to the heterogeneous network; a distribution step in which the distribution device distributes information about the communication path acquired in the first acquisition step to the first transfer device and the second transfer device; a second acquisition step in which the first transfer device or the second transfer device acquires a packet and information about the communication path distributed in the distribution step; a first determination step in which the first forwarding device or the second forwarding device determines whether the destination IP address of the packet acquired in the second acquisition step matches information about the communication path acquired in the second acquisition step; a first rewriting step of rewriting a header of the packet acquired in the second acquisition step based on information about the communication path acquired in the second acquisition step when it is determined that the first transfer device or the second transfer device matches in the first determination step; a first transmission step in which the first forwarding device or the second forwarding device transmits the packet whose header has been rewritten in the first rewriting step to the first forwarding device or the second forwarding device that exists in a different VPN; A communication method comprising:

6. A communication program that causes a computer to execute a communication method implemented by a communication system that includes a distribution device, a first transfer device, and a second transfer device, the first transfer device and the second transfer device being in different VPNs, The computer as the distribution device a first acquisition step of acquiring information about a communication path including information about an IP address pool, information about a destination IP address to be distributed to a heterogeneous network, and information about a path to a transfer device that accommodates a terminal having a destination IP address to be distributed to the heterogeneous network; a distribution step of distributing information about the communication path acquired by the first acquisition step to the computer serving as the first transfer device and the computer serving as the second transfer device; Execute a computer as the first transfer device and a computer as the second transfer device; a second acquisition step of acquiring packets and information about the communication path distributed by the distribution step; a first determination step of determining whether or not the destination IP address of the packet acquired in the second acquisition step matches information about the communication path acquired in the second acquisition step; a first rewriting step of rewriting the header of the packet acquired in the second acquisition step based on information about the communication path acquired in the second acquisition step when it is determined that there is a match in the first determination step; a first transmission step of transmitting the packet whose header has been rewritten in the first rewriting step to a computer serving as the first forwarding device or a computer serving as the second forwarding device that exists in a different VPN; A communication program characterized by causing the program to execute the above.

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