JP2008211550A - Data transfer method in mpls network, edge router, as boundary router, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the number of LSPs (Label Switched Path) necessary to an MPLS (Multi-Protocol Label Switching) network smaller than in the conventional art. <P>SOLUTION: This data transfer method in the MPLS network 1 is provided with a plurality of ASs (Autonomous System) including MPLS routers having a label switching function. An edge router A for transmitting a packet to an edge router G to be a destination adds each label showing the whole ASs where the packet passes through and a label showing the edge router G of the destination to the packet to be an MPLS frame and transmits the MPLS frame to an AS boundary router B in the same AS21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication technique using MPLS (Multi-Protocol Label Switching).

  In recent years, new services such as IP (Internet Protocol) telephones and IP broadcasting have appeared, and the transition from existing leased line services to IP network services has progressed. Various services can be integrated into IP networks. Expected. In order to accommodate various services in an IP network, MPLS (from the viewpoint of logical separation of a plurality of services (realizing a plurality of services using the same physical communication line) and improvement of reliability) For example, utilization of nonpatent literature 1) is anticipated.

  MPLS is a technology for connection-type communication (communication performed by communication devices confirming that data has arrived at a communication partner), and a short fixed-length label indicating route information or the like is added to a transfer packet. In this technique, the interpretation of the IP header in the router is omitted, that is, a technique using a label switching function. In MPLS, it is necessary to manage a label switched path (LSP) that is a virtual path that is not necessary in a conventional IP network.

  As the MPLS network becomes larger, the number of required LSPs increases rapidly. In particular, when MPLS is applied to a service mainly composed of communication between user equipments such as IP telephones, a full mesh is connected between edge routers accommodating user equipments (each base is connected to all other bases. LSP in the state of the eye) is required. When establishing an LSP in a full mesh, the number of LSPs required for the entire network is on the order of the square of the number of edge routers.

That is, when the number of edge routers is several hundred, tens of thousands to hundreds of thousands of LSPs are required, but it is practically difficult to manage and manage tens of thousands of LSPs. In order to solve this problem, for example, Non-Patent Document 2 discloses a technique for reducing the number of LSPs by dividing a network into a plurality of domains (areas) and establishing an LSP for each domain. Yes.
E. Rosen, A. Viswanathan, R. Callon, "MultiprotocolLabel Switching Architecture", RFC3031, [online], January 2001, IETF, Section 2.1, 3.1-3.6, 3.9, 3.25, 3.27, [February 19, 2007 Search], Internet <URL: http://www.ietf.org/rfc/rfc3031.txt> Hisashi Kojima, 4 others, “Examination of large-scale MPLS network by domain partitioning”, IEICE General Conference, March 2006, B-6-89

  However, the technique of Non-Patent Document 2 described above is applicable only to OSPF (Open Shortest Path First) multi-areas. There is also an AS (Autonomous System) as an area unit. For example, one AS can include a multi-area of OSPF. The technique of Non-Patent Document 2 described above has a problem that it cannot be applied to an MPLS network composed of a plurality of ASs due to a difference in protocol.

  Therefore, the present invention has been made in view of the above-described problems, and an object thereof is to reduce the number of LSPs required for an MPLS network as compared with the prior art.

  In order to solve the above-mentioned problem, an invention according to claim 1 is a data transfer method in an MPLS network including a plurality of ASs including a plurality of MPLS routers having a label switching function. The MPLS router includes an edge router connected to user equipment outside the MPLS network, and an AS boundary router located at the boundary with another AS. LSPs are established between the edge router and AS border routers in the same AS, and between AS border routers of different ASs. The source edge router that is an edge router that transmits a packet to the destination edge router that is the destination edge router assigns each label indicating all ASs through which the packet passes and a label indicating the destination edge router to the packet. The MPLS frame is sent to the AS border router in the same AS. The AS border router determines an AS to be the next transfer destination based on the label included in the received MPLS frame, and forwards the MPLS frame to the AS border router of the AS. The AS border router in the same AS as the destination edge router refers to the label indicating the destination edge router included in the received MPLS frame and transfers the MPLS frame to the destination edge router.

  According to this invention, the number of LSPs required for the MPLS network can be reduced as compared with the prior art by establishing LSPs for each AS and switching LSPs at the AS boundaries.

  The invention according to claim 2 is the data transfer method in the MPLS network according to claim 1, wherein the source edge router includes each label indicating all ASs through which the packet passes and a label indicating the destination edge router. Arranged from the outside in the order referred to by each AS border router that forwards the MPLS frame. The AS border router determines the AS to be the next transfer destination based on the label value arranged at the outermost side of the received MPLS frame, and when transferring the MPLS frame to another AS at the time of transfer, the outermost side Delete after referencing the label placed in.

  According to this invention, the labels indicating all the ASs through which the packet passes and the labels indicating the destination edge routers are arranged from the outside in the order referred to by the AS border routers that transfer the MPLS frames. The present invention can be realized.

  The invention according to claim 3 is the data transfer method in the MPLS network according to claim 1 or claim 2, wherein the MPLS router uses BGP as a routing protocol and uses an AS number as a label value indicating AS. . The destination edge router advertises a label indicating itself to the entire MPLS network using BGP in advance. Based on each AS number indicating all ASs through which packets received by BGP and labels indicating destination edge routers are sent, the source edge router determines all AS numbers and destination edge routers that pass through the packets to be transmitted. The label shown is given.

  With this invention, the use of labels indicating all ASs through which packets pass and labels indicating destination edge routers is extended to BGP (existing BGP and advertise labels indicating new destination edge routers) The same applies to the following), and development of a new protocol can be eliminated.

  According to the inventions of claims 4 to 6 and claims 7 to 9, the edge router and the AS boundary router in the inventions of claims 1 to 3, respectively, can be realized. According to the invention of claim 10, a program for causing a computer to execute the invention of claims 1 to 3 can be realized.

  According to the present invention, the number of LSPs required for an MPLS network can be reduced as compared with the prior art.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings. In the present embodiment, a network composed of a plurality of ASs is assumed. Further, BGP (Border Gateway Protocol) is used as a routing protocol between ASs. Further, it is assumed that BGP is extended to carry label information as means for advertising a label for identifying a destination edge router (hereinafter also referred to as “router label”) to the network. In addition, according to the specification of MPLS (Penultimate Hop Popping), the transfer label (hereinafter referred to as “* 1”, etc.) shall be removed one hop before the LSP end point, and there is only one hop. In the case of LSP, the transfer label is not given from the beginning.

  FIG. 1 is an overall configuration diagram showing an MPLS network and the like of the present embodiment. As shown in FIG. 1, the MPLS network 1 includes four ASs (hereinafter referred to as AS21 (2), AS22 (2), AS23 (2), and AS29 (2) that connect these AS21 to 23 to each other. The four ASs are collectively referred to as “AS2” or “AS”). Each AS may be assigned to different operators, or one assigned to the same operator (for example, dividing one AS for the purpose of improving the scalability of the routing protocol). For example, the sub AS may be used.

  Each AS 2 has all or some types of AS border routers 3, edge routers 4, and relay routers 5 that are MPLS routers that realize MPLS (that is, have a label switching function). The AS boundary router 3 is an MPLS router located at the boundary with another AS, and specifically, MPLS routers B, C, D, E, F, and H (hereinafter also simply referred to as “router B” or the like). ). The edge router 4 is an MPLS router that exists at the edge of the AS and accommodates user equipment, and specifically, routers A, G, and I. The relay router 5 is an MPLS router located on the path of the LSP. In FIG. 1, only one router is shown between routers A and B, between routers C and D, and between routers F and G. There may be two or more in each location, or they may exist in other locations.

  The AS border router 3 and the edge router 4 have functions specific to the present embodiment. However, the relay router 5 is an MPLS router having a normal (conventional) label switching function, and will be described in detail below. Since it is not necessary to have a function peculiar to the embodiment, a detailed description of its configuration and function is omitted.

  At the boundary of each AS2, LSP6 is established between AS boundary routers 3 belonging to each AS. Also, a BGP peer 7 for exchanging route information and a router label indicating the edge router 4 is established in the same section as the LSP 6. In the present embodiment, a user device having an IP address “aa” in the user network 8 is accommodated in the router G.

  Next, configurations and functions of the AS boundary router 3 and the edge router 4 will be described. In addition, regarding the AS boundary router 3 and the edge router 4, the same configuration and function will be described as the representative of the AS boundary router 3, and the different functions will be described respectively. FIG. 2 is a block diagram showing configurations and functions of the AS boundary router and the edge router.

As shown in FIG. 2, the AS border router 3 includes a processing unit 110, a label DB (database) 104, a BGP table 105, a label table 106 (label information), a network interface 107, and a switch 108.
The processing unit 110 is a means for performing each processing in the AS border router 3, and in particular, those greatly related to the present embodiment are the BGP protocol processing unit 101, RSVP (Resource reSerVation Protocol) protocol processing. Part 102 and label processing part 103. In the following description, when the processing unit 110 performs processing as a normal MPLS router, “processing unit 110” is described as an operation subject.

  The AS border router 3 is specifically a computer device, and although not particularly shown, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an HDD (Hard Disk Drive). Etc. The label DB 104, the BGP table 105, and the label table 106 are information stored in a storage device such as an HDD. The processing unit 110 is realized by a program execution processing function by the CPU.

  The BGP protocol processing unit 101 operates a BGP protocol compliant with a standard such as RFC (Request For Comment). That is, the BGP protocol processing unit 101 establishes a BGP session such as e (External) BGP or i (Internal) BGP with another router, and establishes the BGP session with route information held by itself. In addition to advertising to the other router, it plays a role of receiving route information from the other router. Then, the route information obtained by the BGP protocol processing unit 101 via the BGP session is stored in the BGP table 105. Further, in addition to the normal function described above, the BGP protocol processing unit 101 also plays a role specific to the present embodiment in which information on the router label indicating the edge router 4 is advertised in the MPLS network 1.

  The RSVP protocol processing unit 102 operates RSVP-TE (Traffic Engineering), which is a signaling protocol for establishing an LSP (a protocol for exchanging information before communication for a path). The RSVP-TE protocol itself uses what is defined as a standard in RFC or the like.

  The label processing unit 103 executes a process of writing the route information received by the BGP protocol processing unit 101 from other AS border routers 3 and edge routers 4 and the label information of the edge routers 4 into the label DB 104. Further, the label processing unit 103 displays the route information (destination IP address) received by the BGP protocol processing unit 101, the AS number through which the destination IP address information has passed, and the router label corresponding to the destination IP address. It writes in the corresponding part of the table 105 (details will be described later in FIG. 4). The label DB 104 and the BGP table 105 are used to generate the label table 106. When each router transfers a packet, the label table 106 may be referred to.

  Further, in the AS border router 3, the label processing unit 103 determines the input label (see FIG. 5) and the output label (the transfer label of the LSP to be transferred next, from the BGP route information and the AS number or router label information. 5) is written in the label table 106. On the other hand, in the edge router 4, the label processing unit 103 writes the correspondence relationship between the destination IP address and the AS number or the router label in the label table 106. These details will be described later together with FIG.

  Next, the label DB 104 will be described. The label DB 104 is information indicating the relationship between the IP address (reference numeral 201) for each edge router, the corresponding AS number (reference numeral 202), and the router label (reference numeral 203). 3 is a configuration table of a label DB. FIG. 3A is a label DB 104A (the label DB 104 of the router A is expressed as “label DB 104A”. The same applies to other label DBs 104) (the same applies to 104B, 104C, and 104D). Yes, (b) is the label DB 104F (see other figures as appropriate). As shown in FIG. 3A, the label DB 104A includes an IP address 201, an AS number 202, and a router label 203 of the edge router. These pieces of information are obtained when the label processing unit 103 writes the route information received by the BGP protocol processing unit 101 (the IP address of the edge router 4) and the corresponding AS number and router label in the corresponding part of the label DB 104A. It is done. The same applies to the label DB 104F in FIG.

  Note that the IP address 201 of the edge router is written only when the edge router exists in the same AS as the AS of the router itself holding the BGP table 105. Since it is the AS border router that exists in the same AS that transmits the packet directly to the edge router, if the edge router does not exist in the same AS, it is necessary to write information to the IP address 201 of the edge router. Because there is no. That is, since the label DB 104F shown in FIG. 3B is for the AS boundary router F existing in the same AS as the edge router G, the IP address 201 of the edge router G is “gg” which is the IP address of the edge router G. Is described. On the other hand, in the label DB 104A shown in FIG. 3A, nothing is written in the IP address 201 of the edge router.

  Next, the BGP table 105 will be described. The BGP table 105 accommodates a destination IP address (IP address of a destination user device; reference numeral 301), an AS_PATH (reference numeral 302) indicating an AS number to reach the destination IP address, and the user equipment of the destination. This is information indicating the relationship of the router label (reference numeral 303) of the edge router. FIG. 4 shows an example of a BGP table. FIG. 4A shows a BGP table 105A (105) (the BGP table 105 of the router A is expressed as “BGP table 105A”. The same applies to other BGP tables 105). (B) is the BGP table 105C (105) (same for the BGP table 105D), and (c) is the BGP table 105F (105) (see other figures as appropriate). As shown in FIGS. 4A to 4C, the BGP table 105 includes a destination IP address 301, an AS_PATH 302, and a router label 303. These pieces of information include the route information received by the BGP protocol processing unit 101 (destination IP address in this case. Here, the IP address “aa” assigned to the user equipment accommodated by the edge router G), and the destination IP address information. Is obtained by the label processing unit 103 writing the router label corresponding to the AS number and the destination IP address that are routed in the BGP table 105.

  In the BGP table 105A of FIG. 4A, the user equipment to which the IP address “aa” is assigned is accommodated under the edge router G having the router label “L100”. It is necessary to go through AS29. The same applies to the BGP table 105C in FIG. The same applies to the BGP table 105F in FIG. 4C, and that nothing is described in the AS_PATH 302 means that the edge router G whose router label is “L100” has the same AS as itself (AS border router F). It means that it exists.

  In FIG. 4, information related to BGP route information related to the present embodiment is extracted and shown. However, various attribute information advertised by BGP (such as next hop (Next_Hop) information). Is included.

  Next, the label table 106 will be described. FIGS. 5A to 5E are examples of label tables (see other figures as appropriate). Hereinafter, first, the label table 106A (106) of the edge router A will be described as a representative. As shown in FIG. 5A, the label table 106A includes a destination IP address 401, an input label 402, an output label 403, and an output interface 404. These pieces of information can be obtained by the label processing unit 103 writing the corresponding information in the label table 106 based on the route information received by the BGP protocol processing unit 101.

  A destination IP address 401 indicates an IP address that is a destination of the input packet. The input label 402 indicates the outermost label of the input MPLS frame (packet and the entire data of each label). An output label 403 indicates a label to be provided on the outermost side of the MPLS frame that is output in response to the input of the label described in the input label 402. The output interface 404 indicates an interface number (identifier of the network interface 107 in FIG. 2) that outputs the MPLS frame.

  As shown in FIG. 5A, in this embodiment, the edge router A sends a packet from the user equipment (not shown) accommodated by itself to the user equipment (IP address “aa”) accommodated by the edge router G. In order to transfer, in the label table 106A, the destination IP address “aa” (reference numeral 401), the output label “L100, 23, 29, * 1 (outside in order from the right)” (reference numeral 403) and the output interface “IF # 2 ( (Interface number where LSP addressed to AS border router B is established) ”(reference numeral 404). The output label “* 1” is a transfer label assigned when the RSVP protocol processing unit 102 establishes an LSP by the RSVP-TE protocol.

  On the other hand, as shown in FIG. 5B, in the label table 106B of the AS border router B, the output label “-(none)” (reference numeral 403) and the output interface with respect to the input label “29” (reference numeral 402). “IF # 1 (interface number where an LSP addressed to AS boundary router C is established)” (reference numeral 404) is associated. Here, the input label is “29” because the outermost “* 1” of the output labels from the edge router A is not received when the AS border router B receives it according to the above-mentioned PHP specifications. This is because the outermost label should be “29”. Since there is one hop between the AS border router B and the AS border router C, there is no need to assign a transfer label according to the PHP specifications, so the output label is “-(none)”.

  Hereinafter, similarly, as shown in FIG. 5C, in the label table 106C of the AS boundary router C, the output label “* 2 (transfer label)” (for the input label “23” (reference numeral 402)) Reference numeral 403) is associated with the output interface “IF # 1 (interface number where the LSP addressed to AS boundary router D is established)” (reference numeral 404).

  Further, as shown in FIG. 5D, in the label table 106D of the AS border router D, the output label “-(none)” (reference numeral 403) and the output interface with respect to the input label “23” (reference numeral 402). “IF # 5 (interface number where LSP addressed to AS border router F is established)” (reference numeral 404) is associated.

  Further, as shown in FIG. 5E, in the label table 106F of the AS boundary router F, the output label “* 3 (forwarding) with respect to the input label“ L100 (router label of the edge router G) ”(reference numeral 402). Label) ”(reference numeral 403) and the output interface“ IF # 2 (interface number where the LSP addressed to the edge router G is established) ”(reference numeral 404) are associated with each other.

  That is, in the AS border routers B, C, and D in the AS (transit AS) in which the edge router 4 that accommodates the destination user device does not exist, the destination of the next transfer of the MPLS frame to the input label 402 of the label table 106 Enter your AS number. Further, in the AS border router F in the AS where the edge router 4 accommodating the destination user device exists, the input label 402 of the label table 106 contains the router label of the edge router G accommodating the destination user device. In either case, the output label 403 contains the transfer label assigned to the LSP to be transferred next (the normal transfer label assigned by RSVP-TE) (if there is only one hop, nothing is entered). ).

  Returning to FIG. 2, the network interface 107 is an interface connected to another MPLS router through an optical fiber or the like, and performs determination of a next hop transfer destination, label swap (conversion or deletion) processing, and the like. The switch 108 is responsible for forwarding the MPLS frame to the appropriate network interface 107. The network interface 107 and the switch 108 can be realized by a dedicated IC (Integrated Circuit) chip, for example.

  Next, the communication procedure in this embodiment will be described. FIG. 6 is a time chart showing the flow of communication procedures in this embodiment. Specifically, steps S1 to S6 are advertisements by the edge router G, and steps S7 to S12 are accommodated from the edge router A to the edge router G. The flow of packet transmission to the user equipment (IP address “aa”) is shown (refer to other figures as appropriate).

  First, referring to steps S1 to S6, the advertisement of the IP address “aa” from the edge router G to another router, the advertisement of the router label (“L100”) of the edge router G, and other related operations are performed. Generation of the label DB 104, the BGP table 105, and the label table 106 in the router will be described.

  The BGP protocol processing unit 101 of the edge router G advertises (transmits) the information of the IP address “aa” to the AS boundary router F by BGP (step S1). Here, the information advertised includes the IP address “aa”, the address of the router G as Next_Hop (indicated simply as “G” in FIG. 6, the same applies hereinafter), the AS_PATH, and the router label (“R” in FIG. 6). "L100") is included as information.

  Note that Next_Hop is information indicating an address to which a packet is to be transferred next in order to reach a destination address (here, “aa”), and is defined by a standard BGP protocol such as RFC. Further, AS_PATH records AS numbers that are passed while this information is propagated (transmitted) in order, and this is also included in the standard BGP protocol.

  That is, of the four pieces of information transmitted in step S1, three of the IP address, Next_Hop, and AS_PATH are defined by the normal (conventional) standard BGP protocol. The remaining router label is information specific to this embodiment, which is an extension of BGP, which is a label corresponding to the edge router G that first advertised the information of the IP address “aa”.

  When receiving information on the IP address “aa” advertised by the edge router G, the AS boundary router F extracts necessary information from the received information and writes it in the label DB 104. Here, as shown in FIG. 3B, the edge router G IP address 201 is described as “gg”, which is the IP address of the edge router G, and there is no AS_PATH information in the received information. Is determined to exist in the same AS as itself (AS border router F), “23”, which is its own AS number, is described in the AS number 202, and “L100” is described in the router label 203.

  Further, the label processing unit 103 of the AS boundary router F extracts necessary information from the received information and writes it in the BGP table 105. Here, as shown in FIG. 4C, “aa” is described in the destination IP address 301 and “L100” is described in the router label 303. Since AS_PATH information is not included, nothing is described in AS_PATH 302.

  Next, the label processing unit 103 of the AS boundary router F generates a label table 106F (see FIG. 5E) using information in the label DB 104F and the BGP table 105F. For example, if an MPLS frame addressed to the edge router G is transferred from another AS, the AS border router F exists in the same AS as the destination edge router G, so the input label value is the router of the edge router G. Since it should be “L100”, the label processing unit 103 of the AS border router F describes “L100” in the input label 402. In addition, the label processing unit 103 of the AS boundary router F sends the output label 403 to the LSP transfer label “* 3 (actually RSVP−) that is addressed to the edge router G that has advertised the information of the IP address“ aa ”. The label value assigned when the LSP is established by the TE protocol) is described. Further, the label processing unit 103 of the AS boundary router F describes the interface number “IF # 2” in which the LSP addressed to the edge router G is established in the output interface 404. Nothing is written in the destination IP address 401.

  Subsequently, the BGP protocol processing unit 101 of the AS boundary router F advertises (transmits) the route information of the IP address “aa” to the adjacent AS boundary router D (step S2). In addition to the IP address “aa”, the advertised information includes the information of the address of the router F as “Next_Hop”, “23” as its AS number as “AS_PATH”, and “L100” as the router label.

  The AS boundary router D that has received the route information generates a label DB 104D (see FIG. 3A) and a BGP table 105D (see FIG. 4B). The generation procedure is the same as that of the AS boundary router F. Therefore, explanation is omitted.

  Further, the label processing unit 103 of the AS border router D generates a label table 106D (see FIG. 5D) using information in the label DB 104D and the BGP table 105D. If an MPLS frame addressed to the edge router G is transferred from another AS, “23” that is the AS number where the edge router G exists is predicted as the input label value. The unit 103 describes “23” in the input label 402. Further, since the relay router 5 does not exist between the AS boundary router D and the AS boundary router F, a transfer label is not required according to the above-described PHP specifications, and the label processing unit 103 of the AS boundary router D outputs an output label 403. Does not list anything. Further, the label processing unit 103 of the AS boundary router D describes the interface number “IF # 5” in which the LSP addressed to the AS boundary router F is established in the output interface 404. Nothing is written in the destination IP address 401.

  Similarly, the BGP protocol processing unit 101 of the AS boundary router D advertises (transmits) the route information of the IP address “aa” to the AS boundary router C (step S3), and the AS boundary router C that has received the route information The label DB 104C (see FIG. 3A), the BGP table 105C (see FIG. 4B), and the label table 106C (see FIG. 5C) are generated.

  Similarly, the BGP protocol processing unit 101 of the AS boundary router C advertises (transmits) the route information of the IP address “aa” to the AS boundary router B (step S4), and the AS boundary router B that has received the route information The label DB 104B (see FIG. 3A), the BGP table 105B (see FIG. 4A), and the label table 106B (see FIG. 5B) are generated.

  Similarly, the BGP protocol processing unit 101 of the AS boundary router B advertises (transmits) the route information of the IP address “aa” to the edge router A (step S5), and the edge router A that has received the route information The DB 104A (see FIG. 3A) and the BGP table 105A (see FIG. 4A) are generated.

  Further, the label processing unit 103 of the edge router A generates the label table 106A (see FIG. 5A) using the information of the label DB 104A and the BGP table 105A (step S6). This is different from the case of the router 3. This is because the edge router A exists at the entrance of the MPLS network 1 and therefore all necessary labels need to be given there.

  Specifically, the label processing unit 103 of the edge router A reads “aa” described in the destination IP address 301 of the BGP table 105A and writes “aa” in the destination IP address 401. Further, the label processing unit 103 of the edge router A does not describe anything in the input label 402. Further, the label processing unit 103 of the edge router A refers to the BGP table 105A and recognizes that the IP address “aa” is accommodated in the edge router of the router label “L100”. L100 "is described. Next, the label processing unit 103 of the edge router A refers to the BGP table 105A, recognizes that it passes through the AS 23 and the AS 29 in order to reach the edge router of the router label “L100”. 23 ”and“ 29 ”are added. Further, the label processing unit 103 of the edge router A adds the transfer label “* 1” of the LSP to the AS border router B described as Next_Hop in the received route information to the output label 403. The label processing unit 103 of the edge router A describes the interface number “IF # 2” in which the LSP addressed to the AS boundary router B is established in the output interface 404.

  In this way, the label DB 104, the BGP table 105, and the label table 106 are generated in the AS boundary router 3 and the edge router 4 of the MPLS network 1.

  Next, the flow of packet transmission (transfer) from the edge router A to the user equipment (IP address “aa”) accommodated in the edge router G will be described with reference to steps S7 to S12.

  When a packet (IP packet, abbreviated as “IP” in FIG. 6) addressed to the IP address “aa” is input to the edge router A from a user device (not shown) accommodated (step S7), the edge router A The processing unit 110 of A refers to the label table 106A, sets “L100”, “23”, “29”, and “* 1” as output labels and adds them to the packet (MPLS frame: reference numeral 801). Transmit to the AS border router B (step S8). The transfer label “* 1” is removed from the relay router 5 immediately before the AS boundary router B (reference numeral 802) according to the specification of the PHP described above, and when the AS boundary router B receives the MPLS frame, The outermost label is “29”.

  When receiving the MPLS frame (reference numeral 802), the processing unit 110 of the AS border router B refers to the label table 106B, and since the input label is “29” and there is no output label, the label “29” is received from the received MPLS frame. And the MPLS frame (reference numeral 901) is transferred to the AS border router C with reference to the output interface 404 (step S9). As a result, even when the AS boundary router B holds a plurality of LSPs, the LSP addressed to the AS boundary router C can be correctly selected from the label “29” in the received MPLS frame and the label table 106B.

  Similarly, the processing unit 110 of the AS boundary router C that has received the MPLS frame (reference numeral 901) refers to the label table 106C and selects the MPLS frame (reference numeral 1001) to which the transfer label “* 2” has been assigned, as the AS boundary router D. (Step S10).

  Similarly, the processing unit 110 of the AS border router D that has received the MPLS frame (reference numeral 1002) from which the transfer label “* 2” has been removed by the immediately preceding relay router 5 refers to the label table 106D and refers to the label “23”. The MPLS frame (reference numeral 1101) from which is removed is transmitted to the AS boundary router F (step S11).

  Similarly, the processing unit 110 of the AS boundary router F that has received the MPLS frame (reference numeral 1101) refers to the label table 106F, removes the label “L100”, and assigns the transfer frame “* 3”. 1201) is transmitted to the edge router G (step S12).

  The processing unit 110 of the edge router G that has received the packet (reference numeral 1202) from which the transfer label “* 3” has been removed by the immediately preceding relay router 5 refers to the IP address and transmits the packet to the user equipment accommodated by itself. To do.

  As described above, according to the AS boundary router 3 and the edge router 4 of the present embodiment, the LSP is divided for each AS, labels corresponding to the AS and the destination edge router 4 are attached, and an MPLS frame is transferred. By switching LSPs at the border router 3, the number of LSPs can be greatly reduced without specially extending the label switching function of a normal MPLS router. That is, the present invention is not limited to an OSPF multi-area, and can be applied to an MPLS network composed of a plurality of ASs.

  In addition, since transfer between LSPs is performed by label switching on the transfer plane (stage) even at the boundary of AS, the confidentiality of IP packets and Ethernet (registered trademark) frames carried by MPLS frames is maintained, and many services are provided. The same service as when the edge routers are connected by a single LSP can be realized, such as there is no concern of duplication of IP addresses even if IPs are multiplexed.

  Furthermore, the MPLS network 1 of the present embodiment only extends BGP, which is a standard protocol most widely used as a routing protocol between ASs in a general IP network, and automatically assigns router labels. Can be realized. Therefore, the burden of label setting can be reduced, and the existing network configuration need not be changed. That is, since the implementation of MPLS transfer by normal label switching can be diverted, it is not necessary to develop new hardware and protocols, and the initial investment cost can be kept low.

  Each process in the AS boundary router 3 and the edge router 4 can be realized by a predetermined person creating and executing a program for causing the CPU of the computer to execute.

This is the end of the description of the embodiments, but the aspects of the present invention are not limited to these.
For example, the number of ASs in the MPLS network 1 is not limited to four and may be any number. In addition, the specific configuration can be changed as appropriate without departing from the spirit of the present invention.

It is a whole lineblock diagram showing the MPLS network etc. of this embodiment. It is a block diagram which shows the structure and function of AS border router and edge router. It is a structure table of label DB. It is a configuration table of a BGP table. It is a structure table of a label table. It is the time chart which showed the flow of the communication procedure in this embodiment.

Explanation of symbols

1 MPLS network 2, 21, 22, 23, 29 AS
3 AS border router 4 Edge router 6 LSP
7 BGP peer 101 BGP protocol processing unit 102 RSVP protocol processing unit 103 label processing unit 106 label table 110 processing unit

Claims (10)

A data transfer method in an MPLS network including a plurality of AS (Autonomous System) including a plurality of MPLS (Multi-Protocol Label Switching) routers having a label switching function,
The plurality of MPLS routers include an edge router connected to user equipment outside the MPLS network, and an AS boundary router located at a boundary with another AS,
An LSP (Label Switched Path) is established between the edge router and the AS border router in the same AS, and between AS border routers of different ASs,
The source edge router that is the edge router that transmits a packet to the destination edge router that is the edge router that is the destination includes each label indicating all ASs through which the packet passes, and a label indicating the destination edge router To the packet to send an MPLS frame to the AS border router in the same AS,
The AS border router determines an AS to be a next transfer destination based on the label included in the received MPLS frame, forwards the MPLS frame to the AS border router of the AS,
An AS boundary router in the same AS as the destination edge router refers to a label indicating the destination edge router included in the received MPLS frame, and forwards the MPLS frame to the destination edge router. Data transfer method. The source edge router arranges each label indicating all ASs through which a packet passes and a label indicating the destination edge router from the outside in the order referred to by each AS border router that forwards the MPLS frame,
The AS border router determines the AS to be the next transfer destination based on the label value arranged on the outermost side of the received MPLS frame, and transfers the MPLS frame to another AS at the time of transfer. The data transfer method in an MPLS network according to claim 1, wherein the data is deleted after referring to a label arranged outside. The MPLS router uses BGP (Border Gateway Protocol) as a routing protocol, uses an AS number as a label value indicating AS,
The destination edge router previously advertises a label indicating itself to the entire MPLS network using the BGP,
The source edge router, based on each AS number indicating all AS through which the packet received by the BGP passes and a label indicating the destination edge router, all AS numbers passing through the packet to be transmitted and the The data transfer method in the MPLS network according to claim 1 or 2, wherein a label indicating a destination edge router is attached. A plurality of AS (Autonomous System) in an MPLS (Multi-Protocol Label Switching) network, and an edge router connected to a user equipment outside the MPLS network among MPLS routers having a label switching function,
When it is a source edge router that is the edge router that transmits a packet to a destination edge router that is the edge router that is a destination,
A processing unit and a storage unit;
The storage unit
Storing label information indicating a relationship between a destination of the packet, each label indicating all ASs through which the packet passes, and a label indicating the destination edge router;
The processor is
Establish an LSP (Label Switched Path) with an AS border router that exists in the same AS and is located at the boundary with another AS
When transmitting a packet to the destination edge router, the label information stored in the storage unit is referred to, and each label indicating all ASs through which the packet passes and a label indicating the destination edge router are assigned to the packet. To make an MPLS frame,
An edge router that transmits the MPLS frame to an AS border router in its own AS in order to transfer the MPLS frame to the AS border router of the AS in which the destination edge router exists. The processing unit of the source edge router refers to the label information stored in the storage unit, and displays each label indicating all ASs through which the packet passes and a label indicating the destination edge router in the MPLS frame. The edge router according to claim 4, wherein the edge routers are arranged from the outside in the order of reference by each AS border router that forwards. A plurality of AS (Autonomous System) in an MPLS (Multi-Protocol Label Switching) network, and an edge router connected to a user equipment outside the MPLS network among MPLS routers having a label switching function,
When the destination edge router is the edge router that receives the packet sent from the source edge router that is the edge router that transmits the packet,
In order to generate label information indicating the relationship between the destination edge router of the packet, each label indicating all ASs through which the packet passes, and a label indicating the destination edge router, a label indicating itself in advance Is advertised to the entire MPLS network using BGP (Border Gateway Protocol). A plurality of AS (Autonomous System) in an MPLS (Multi-Protocol Label Switching) network, and an AS border router located at a boundary with another AS among MPLS routers having a label switching function,
A processing unit and a storage unit;
The storage unit
Stores label information indicating the relationship between the destination of the packet and the label indicating the AS or destination edge router as the next transfer destination,
The processor is
Establish an LSP (Label Switched Path) with an AS border router of a different AS,
When an MPLS frame, which is data with a label attached to a packet, is received, the label information stored in the storage unit is referred to, and the AS serving as the next transfer destination based on the label included in the MPLS frame or the An AS border router, wherein a destination edge router is determined and an MPLS frame is forwarded to the forwarding destination. When the processing unit receives an MPLS frame in which labels are arranged from the outside in the order used by each AS boundary router that forwards the MPLS frame by the source edge router of the packet, the processing unit displays the label information stored in the storage unit. Referring to this, when the AS to be the next transfer destination is determined based on the label arranged on the outermost side of the MPLS frame, and the MPLS frame is transferred to the AS border router of another AS at the time of transfer, The AS boundary router according to claim 7, wherein the AS border router is deleted after referring to the label arranged on the outermost side. The MPLS router uses BGP (Border Gateway Protocol) as a routing protocol, uses an AS number as a label indicating AS,
The processing unit of the AS border router stores the label indicating the destination edge router advertised to the entire MPLS network by the destination edge router in the label information of the storage unit by applying the BGP. The AS border router according to claim 7 or 8, wherein the AS border router is used.   A program for causing a computer to execute the data transfer method in the MPLS network according to any one of claims 1 to 3.

Images