JP2008054151A - Mpls network system, mpls router, and path setting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish an LSP (Label Switched Path), to automatically establish eBGP (External Border Gateway Protocol) peers on the LSP and to automatically perform a traffic mapping to the LSP with respect to routers straddling over a plurality of ASs (Autonomous System) in a large-scale network composed of the plurality of ASs. <P>SOLUTION: This invention relates to a system or a path setting method for an MPLS (Multi-protocol Label Switching) network with the plurality of ASs having one or more MPLS routers. A first MPLS router and a second MPLS router existing in mutually different Ass in which starting points, end points and paths match to each other establish the eBGP peers on two LSPs opposite to each other, exchange mutual path information by the eBGPs, compare the exchanged path information with path information before establishing the eBGP peers and when the exchanged path information is the shorter one, rewrite path information of routing tables of themselves to the exchanged path information, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to path setting in communication using MPLS (Multi-protocol Label Switching).

  In recent years, new services such as IP (Internet Protocol) telephone and IP broadcasting have appeared, and the transition from existing leased line services to IP network services has progressed. It is expected that various services will be integrated into IP networks. ing. In order to accommodate various services in the IP network, it is expected to use MPLS (for example, see Non-Patent Document 1) from the viewpoint of improving reliability and quality assurance.

  MPLS is a technology of connection-type communication (communication that is performed while communication devices confirm that data has reached a communication partner), and by adding a short fixed-length label indicating route information or the like to a transfer packet, This is a technique for omitting interpretation of the IP header in the router, that is, a technique using a label switching function. In MPLS, in addition to a technology for establishing a LSP (Label Switched Path), which is a virtual path created in an MPLS network, how IP packets are transferred, that is, correspondence between a destination IP address and an LSP (traffic) How to determine (mapping) is important.

  In traffic mapping, LSP is considered as an OSPF (Open Shortest Path First) link (a communicable route) that is one of the path selection (routing) protocols in TCP / IP (Transmission Control Protocol / Internet Protocol). It is used inside an iBGP (Internal Border Gateway Protocol: same AS (Autonomous System)) used in a built-in technique (for example, see Non-Patent Document 2) or VPN (Virtual Private Network) using MPLS. A method of associating (BGP) and LSP (for example, see Non-Patent Document 3) is used.

However, since the technique of Non-Patent Document 2 regards the LSP as a link, its application is limited to the OSPF area where the link state information of OSPF is shared. Further, since the technique of Non-Patent Document 3 uses iBGP, its application is limited to the same AS.
Therefore, in these methods, traffic mapping for LSPs across multiple ASs cannot be linked with a routing protocol, and the destination router and the LSP are statically (assumed to be fixed) to the MPLS router that is the starting point of the LSP. Needs to be set.

On the other hand, a large-scale IP network such as a carrier (communication carrier) backbone network is generally composed of a plurality of ASs from the viewpoint of improving the scalability of the routing protocol. At this time, there is an increasing need to establish an LSP across a plurality of ASs in order to increase the speed of switching between a client and a server that exist between different ASs or between users and a communication failure.
E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol Label Switching Architecture", RFC3031, [online], January 2001, IETF, [searched August 3, 2006], Internet <URL: http: // www .ietf.org / rfc / rfc3031.txt> K.Kompella, Y.Rekhter, "Label Switched Paths (LSP) Hierarchy with Generalized Multi-Protocol Label Switching (GMPLS) Traffic Engineering (TE)", p.4 "3. Routing Aspects", RFC4206, [online], October 2005, IETF, [Search August 3, 2006], Internet <URL: http://www.ietf.org/rfc/rfc4206.txt> E. Rosen, Y. Rekhter, "BGP / MPLS IP Virtual Private Networks (VPNs)", p. 23 "5. Forwarding", RFC4364, [online], February 2006, IETF, [searched August 3, 2006 ], Internet <URL: http://www.ietf.org/rfc/rfc4364.txt>

  However, as described above, in the conventional technology, traffic mapping for an LSP established across a plurality of ASs cannot be linked with a routing protocol. Route information must be set, and when the number of users and nodes increases, it is necessary to set corresponding route information one by one. Therefore, there is a problem in terms of maintenance and operation, and there is a problem that it is difficult to apply to a large-scale network such as a carrier network.

  Therefore, the present invention has been made in view of the above problems, and in a large-scale network composed of a plurality of ASs, after establishing an LSP that straddles a plurality of ASs, the eBGP ( External Border Gateway Protocol: The purpose is to establish a BGP (connection) used between a plurality of ASs and automatically perform traffic mapping for the LSP.

In order to solve the above-mentioned problems, the invention according to claim 1 and claim 6 is a system or a route setting method in an MPLS network including a plurality of ASs having one or more MPLS routers.
Then, the first MPLS router and the second MPLS router that exist in different ASs establish eBGP peers after establishing two LSPs in opposite directions with the same start point, end point, and route, and each other by eBGP. If the exchanged route information is a shorter route, the exchanged route information of its own routing table is exchanged for each of the exchanged route information. The route information is rewritten.

  According to this invention, an MPLS router in an MPLS network can establish an eBGP peer after establishing two LSPs in opposite directions with an MPLS router having a different AS, and reflect the route of the LSP in the routing table. it can.

In the invention according to claim 2 and claim 7, when the eBGP peer is established after establishing the above two LSPs between the first MPLS router and the second MPLS router, the first MPLS router The RSVP-TE Path message, which is a signaling protocol for establishing the first LSP that is the LSP in the first direction, which is the direction from the first MPLS router to the second MPLS router, The identifier is added and transmitted to the second MPLS router.
Then, the second MPLS router that has received the Path message adds its own AS identifier to the Resv message that is the response and sends it back to the first MPLS router, and in the LSP in the direction opposite to the first direction. In order to establish a certain second LSP, a Path message with its own AS identifier added is transmitted to the first MPLS router.
Also, the first MPLS router that has received the Resv message for establishing the first LSP reads the AS identifier of the second MPLS router added to the Resv message, and completes the establishment of the first LSP. When the Path message for establishing the second LSP is received, the identifier of the AS is added to the Resv message as a response to the Resv message and transmitted to the second MPLS router, and eBGP with the second MPLS router is transmitted. Set up to establish a peer.
Further, the second MPLS router that has received the Resv message for establishing the second LSP reads the AS identifier of the first MPLS router added to the Resv message, and establishes the second LSP. Set up to establish an eBGP peer with the first MPLS router.

  According to this invention, the first MPLS router and the second MPLS router can automatically perform the setting when the eBGP peer is established after the two LSPs are established.

The invention according to claim 3 and claim 8 is an MPLS router arranged in each AS or a route setting method thereof in an MPLS network having a plurality of ASs.
Then, the MPLS router creates two LSPs in opposite directions that have the same start point, end point, and route between a routing table that stores route information and another MPLS router that exists in an AS different from its own AS. After establishing the eBGP peer, exchange route information with other MPLS routers by eBGP, compare the exchanged route information with the route information before establishing the eBGP peer, and exchange the exchanged route information. When the information is a shorter route, a BGP protocol processing unit for rewriting the route information in the routing table with the exchanged route information is provided.

  According to this invention, an MPLS router in an MPLS network can establish an eBGP peer after establishing two LSPs in opposite directions with an MPLS router having a different AS, and reflect the route of the LSP in the routing table. it can.

In the inventions according to claims 4 and 9, the MPLS router further includes an RSVP protocol processing unit that performs processing related to RSVP-TE, which is a signaling protocol for establishing the LSP.
Then, when establishing an eBGP peer after establishing an LSP, if it is an MPLS router that sends the first Path message that establishes an LSP, the RSVP protocol processing unit can transfer from its own MPLS router to another MPLS router. The RSVP-TE Path message for establishing the first LSP that is the LSP in the first direction that is the direction is added with the identifier of its own AS and transmitted to the other MPLS router, and the other MPLS router transmits the message. When the Resv message as a response is received, the AS identifier of the other MPLS router added to the Resv message is read to establish the first LSP, and the other MPLS router uses the LSP in the direction opposite to the first direction. When a Path message for establishing a certain second LSP is received, Re as a response v and adding an identifier of the own AS in the message sent to the other MPLS routers performs setting to establish eBGP peer with other MPLS routers.
In addition, when the RSVP protocol processing unit receives a Path message from another MPLS router when it is the MPLS router that receives the first Path message for establishing an LSP, the RSv protocol processor adds the AS identifier to the RSVP protocol processing unit. When a message is returned, the AS message is sent with the AS identifier added to the Path message for establishing the LSP in the opposite direction, and when the Resv message is received, the other MPLS routers attached to the Resv message The AS identifier is read to establish an LSP in the opposite direction, and settings are made to establish an eBGP peer with another MPLS router.

  According to this invention, the MPLS router in the MPLS network can automatically perform the setting when the eBGP peer is established after the two LSPs are established.

  In the invention according to claim 5 and claim 10, when the MPLS router is an MPLS router that transmits the first Path message for establishing the LSP, the RSVP protocol processing unit receives a setting input for establishing the LSP. As a trigger, processing for establishing the LSP is started.

  According to such an invention, the MPLS router in the MPLS network can automatically perform the subsequent processing only when the setting input for establishing the LSP by the operator is performed once.

  According to the present invention, in a large-scale network composed of a plurality of ASs, after establishing an LSP that spans a plurality of ASs, an eBGP peer is automatically established on the LSP, and traffic mapping for the LSP is automatically performed. Can be done.

Hereinafter, the best mode (hereinafter referred to as an embodiment) for implementing an MPLS network system in an MPLS network according to the present invention will be described with reference to the drawings as appropriate.
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 is composed of AS 21, 22, 23, and four ASs (hereinafter, reference numerals are omitted) AS 20 that connect the ASs 21 to 23 to each other. 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 includes an MPLS router 3 that implements MPLS (that is, has a label switching function) and an edge router 4 that accommodates a subnet 5 that is a user network. Specifically, among the 11 routers A to K, the routers A, F, and I are the edge routers 4 and the other eight are the MPLS routers 3. Of the eight MPLS routers 3, the shaded routers B (first MPLS router), C, D, E (second MPLS router: “other MPLS router” viewed from the router B), G Since the six routers H and H are located at the boundary of each AS, they serve as AS boundary routers.

The AS border router establishes the BGP session 6 of the eBGP with the AS border router of the adjacent AS, advertises the route information in the own AS to the adjacent AS, and the route information held by the adjacent AS. Receive. In addition, the AS border router establishes the BGP session 6 of iBGP in the AS for the purpose of exchanging the user's route information with other AS border routers (routers D and G when viewed from the router C).
Further, in the present embodiment, LSP (LSP 71 (first LSP in the first direction)) and LSP 72 (second LSP 72) are connected between router B, which is the AS boundary router of AS 21, and router E, which is the AS boundary router of AS 22. A second LSP of direction)) is established, details of which will be described later.

  Next, the configuration of the MPLS router will be described with reference to FIG. 2 (see FIG. 1 as appropriate). FIG. 2 is a configuration diagram of the MPLS router. In FIG. 2, the portion related to the operation of the routing protocol and the operation of the MPLS performed in the present embodiment is mainly shown in the actual configuration of the MPLS router.

As shown in FIG. 2, the MPLS router 3 includes a processing unit 200, a BGP table 203, an LSP / DB (Data Base) 204, and a routing table 205.
The processing unit 200 is a means for performing each processing in the MPLS router 3, and in particular, those greatly related to the present embodiment are a BGP protocol processing unit 201, an RSVP (Resource reSerVation Protocol) protocol processing unit. 202, an LSP establishment instruction processing unit 206 and a BGP peer setting instruction processing unit 207. In the following description, when the processing unit 200 performs normal processing as the MPLS router 3, “processing unit 200” is described as an operation subject.

  The MPLS 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), a HDD (Hard Disk Drive), It consists of an input / output interface. The BGP table 203, the LSP / DB 204, and the routing table 205 are information stored in a storage device such as an HDD. The processing unit 200 is realized by a program execution processing function by the CPU.

  The BGP protocol processing unit 201 operates a BGP protocol compliant with a standard such as RFC (Request For Comment). That is, the BGP protocol processing unit 201 establishes a BGP session such as eBGP or iBGP with another router, advertises the route information held by itself to the router of the other party that has established the BGP session, It is responsible for receiving route information from the other router. Then, the route information obtained by the BGP protocol processing unit 201 via the BGP session is stored in the BGP table 203.

  Further, in the present embodiment, RSVP-TE (Traffic Engineering) is used as a signaling protocol (protocol for information exchange performed for the original communication) used for establishing the LSP, and a signaling message is used. In this case, the AS number of the end point of the LSP is notified. Note that the router that has received the signaling message recognizes that the AS number is added to the signaling message, so that the router that has transmitted the signaling message requests that the LSP be automatically set. I can know.

  Then, the RSVP protocol processing unit 202 operates RSVP-TE which is a signaling protocol for establishing the LSP, and establishes the LSP along the designated route with respect to the router designated by the operator of the MPLS router 3. . When the LSP is established, the RSVP protocol processing unit 202 stores information on the LSP in the LSP / DB 204 through the LSP establishment instruction processing unit 206.

Here, the configuration of the BGP table 203 will be described with reference to FIG. 3 (see FIGS. 1 and 2 as appropriate). FIG. 3 is a configuration diagram of the BGP table. Here, the case of the BGP table of router B is illustrated as an example.
As illustrated in FIG. 3, the BGP table 203 includes information such as a destination address 301, a NextHop 302, and AS_PATH 303.

A destination address 301 indicates an address of a destination (network (subnet) or router) included in the route information transferred via one or more BGP sessions 6.
NextHop 302 indicates the address of the nearest router that has advertised the route information related to the destination described in the destination address 301. However, the router that enters the NextHop 302 is not necessarily a physically adjacent router. For example, when viewed from the router B, the router may be the router C or the router E.
AS_PATH 303 indicates an AS identifier (hereinafter referred to as an AS number) through which the route information has passed.

In the BGP table 203, a table entry (one line of the BGP table 203) is created for each route information advertised by BGP.
Note that unlike the routing table 205, the BGP table 203 is not a database that is directly referred to at the time of packet transfer, but for storing information that is the basis for creating the routing table 205.
In fact, since BGP can advertise a large amount of attribute information, a general router BGP table 203 stores a large amount of information other than that shown in FIG. However, only the information directly related to the present embodiment is described here.

Next, the configuration of the LSP / DB 204 will be described with reference to FIG. 4 (see FIGS. 1 and 2 as appropriate). FIG. 4 is a configuration diagram of the LSP / DB. Here, the LSP / DB of the router B is illustrated as an example.
As shown in FIG. 4, the LSP / DB 204 has information such as an LSP / ID 401, a start point address 402, an end point address 403, a start point AS number 404, and an end point AS number 405.

The LSP ID 401 is an identifier for identifying each LSP in the router.
The starting point address 402 indicates the IP address of the router that is the starting point of the LSP.
The end point address 403 indicates the IP address of the router that is the end point of the LSP.
The starting point AS number 404 indicates the AS number of the starting point of the LSP.
The end point AS number 405 indicates the AS number of the end point of the LSP.
Each entry is created for each LSP whose own router is the start or end point.
In addition to the information shown in FIG. 4, there are various types of information related to the LSP, such as the route, bandwidth, and status of the LSP, but only information directly related to the present embodiment is described here. .

  Next, the configuration of the routing table will be described with reference to FIG. 5 (see FIGS. 1 and 2 as appropriate). FIG. 5 is a configuration diagram of the routing table, where (a) is before LSP establishment, and (b) is after LSP establishment. Here, the case of the routing table of router B is illustrated as an example.

As shown in FIG. 5A, the routing table 205a before LSP establishment includes information such as a destination address 501, a next hop 502, an output IF (interface) number 503, and the like. Note that the routing table 205a may include other information.
A destination address 501 indicates an address of a packet transfer destination (destination).
The next hop 502 indicates the address of the adjacent router to which the packet is to be transferred next to reach the destination address 501. Note that, unlike the NextHop 302 in FIG. 3, the router that enters the next hop 502 is always a physically adjacent router.
The output IF number 503 indicates the number of an interface (not shown in FIG. 2 or the like) to which a packet is to be output in order to reach the router described in the next hop 502.

Further, as shown in FIG. 5B, in the routing table 205b after the LSP is established, it is possible to register the identifier of the LSP (see the LSP / ID 401 in FIG. 4) instead of the router in the next hop 502. .
The routing table 205a or 205b is referred to by the processing unit 200 every time the MPLS router 3 receives a packet, and is used to search for the next hop 502 using the destination (IP) address written in the packet as a key. .

  Returning to FIG. 2, the LSP establishment instruction processing unit 206 plays a role of instructing the RSVP protocol processing unit 202 to establish an LSP. Specifically, when the LSP establishment instruction processing unit 206 receives the RSVP-TE Path message to which the AS number information is added, the LSP establishment instruction processing unit 206 establishes an LSP in the opposite direction to the LSP to be established by the Path message. The RSVP protocol processing unit 202 is instructed to transmit the signaling message. At this time, the LSP establishment instruction processing unit 206 simultaneously instructs the RSVP protocol processing unit 202 to add its own AS number (hereinafter referred to as its own AS number) to the signaling message. The LSP establishment instruction processing unit 206 notifies the BGP peer setting instruction processing unit 207 of its own AS number, the IP address of the other end of the LSP, and the AS number when the establishment of two bidirectional LSPs is completed. To do.

  When the BGP peer setting instruction processing unit 207 receives a notification of LSP establishment completion from the LSP establishment instruction processing unit 206 together with its own AS number, the IP address of the other end of the LSP, and the AS number, the BGP protocol processing unit 201 Information is notified to instruct the establishment of a BGP peer. That is, it is the BGP protocol processing unit 201 that actually establishes the BGP peer.

Next, the operation of each router in the MPLS network of this embodiment will be described with reference to FIG. 6 (see FIGS. 1 to 5 as appropriate). FIG. 6 is a flowchart showing an operation flow of each router in the MPLS network according to the present embodiment.
Here, the process of step S1 is performed with the subnet 5a, which is one of the user networks, connected to the router F and triggered by various settings for the connection made by the operator in the router F. Shall. Then, a case where an LSP is established between the router E and the router B and then an eBGP peer is automatically established on the LSP will be described.

  First, immediately after the setting for connection of the subnet 5a is performed by the operator in the router F, the router F advertises the information of the subnet 5a in the MPLS network 1, that is, here, the routers E, D, and C Via the router B (steps S1 to S4). Note that the processing unit that transmits and receives information for this advertisement in each router is the processing unit 200 in FIG. The route advertisement by BGP here is based on standards such as RFC, and when a route is advertised in the eBGP section, AS_PATH (see AS_PATH 303 in FIG. 3) of the route information has an AS number. Added.

  Here, when the advertisement is performed from the router F to the router E, information such as “destination 5a, NextHop = F, AS_PATH = none” is transmitted (step S1), but the advertisement is performed from the router E to the router D. At this time, the AS number “22” is added to AS_PATH (step S2). Similarly, when the advertisement is performed from the router C to the router B, the AS number “20” is added to the AS_PATH (step S4).

  The BGP protocol processing unit 201 of the router B that has received the route information of the subnet 5a writes the route information in the BGP table 203 (step S5). Specifically, as shown in FIG. 3, the address of the subnet 5a is included in the destination address 301, and the address of the router that advertised the BGP route information last in the NextHop 302 (here, the address of the router C (hereinafter, “ May be omitted.)), But AS_PATH 303 stores a list of AS numbers included in the route information of subnet 5a.

  Here, the BGP protocol processing unit 201 creates the routing table 205 based on the BGP table 203. Here, since the LSP has not been established yet, the next hop 502 in the routing table 205a (see FIG. 5A) is the same router C as the Next Hop 302 in the BGP table 203 (see FIG. 3). That is, the first row of the routing table 205a in FIG. 5A is a routing entry (registration of route information) of the subnet 5a. The operation of each router so far is the same as the BGP operation of the conventional router.

Returning to FIG. 6, the procedure for establishing the LSP will be described.
Router B accepts a setting input for establishing an LSP for router E by the operator (step S6). Examples of setting input items include the destination address of the LSP (address of the router E), the route of the LSP (routers C, D, and E), the bandwidth of the LSP (100 Mbps, etc.), and the like.

  Then, the RSVP protocol processing unit 202 of the router B transmits a Path message, which is a signaling message for establishing an LSP whose starting point is the router B (AS21), to the router E (step S7). Here, in addition to the standard object (content of information), the RSVP protocol processing unit 202 adds an extended object indicating the AS number “21” of router B, which is a feature of the present embodiment, to the Path message. Then, the Path message reaches the router E via the router C and the router D on the way.

  When the router E receives the Path message from the router B (after step S7), the router E returns a Resv message (reserve request for network resources) as a response to the router B (step S8). At this time, the RSVP protocol processing unit 202 of the router E adds the AS number “22” of the router E to the Resv message because the extended object indicating the AS number is included in the received Path message.

  Further, since the RSVP protocol processing unit 202 of the router E includes the extended object indicating the AS number in the received Path message, this signaling message automatically performs the reverse LSP which is a feature of this embodiment. The path message for establishing the LSP in the reverse direction (starting from the router E (AS22)) is transmitted to the router B (step S9). At this time, the AS number “22” of the router E is added to the Path message by the RSVP protocol processing unit 202 of the router E as in the case of step S7.

  After step S8, when the router B receives the Resv message from the router E, which is a response to the Path message transmitted in step S7, the establishment of the LSP is completed at that stage, and the LSP indicated by the RSVP protocol processing unit 202 is received. The establishment instruction processing unit 206 registers LSP information in the LSP / DB 204 (step S10). Specifically, for example, as shown in the first line of the LSP / DB 204 in FIG. 4, the LSP / ID 401 is “71”, the start address 402 is the router B, the end address 403 is the router E, and the start AS number 404 is the router. The LSP information of 21 as the AS number to which B belongs and the end point AS number 405 as “22” as the AS number described in the Resv message is registered.

  Next, when the router B receives the Path message transmitted by the router E to establish the LSP in the reverse direction at step S9, the router B includes the information of the AS number in the Path message. The unit 202 adds its own AS number “21” to the Resv message as a response and sends it back to the router E (step S11).

  Further, immediately after step S11, in the router B, the BGP protocol processing unit 201 instructed by the BGP peer setting instruction processing unit 207 automatically performs setting for establishing an eBGP peer for the router E. The setting of the eBGP peer requires information about its own AS number “21”, the peer destination IP address (router E), and the peer destination AS number “22”. Since it is included in the signaling message transmitted by the router E in S9, the setting is automatically completed even if the operator does not input the setting. However, at this stage, the eBGP peer has not been established since the eBGP setting in the peer destination router E has not yet been performed.

  Subsequently, when the router E receives the Resv message transmitted by the router B in step S11, the LSP establishment instruction processing unit 206 instructed by the RSVP protocol processing unit 202 registers the LSP information in the LSP / DB 204 (step S11). Along with S12), eBGP is set. In this eBGP setting, the peer destination is router B, the AS number of the peer destination is “21”, and the self AS number is “22”.

  At this stage, since eBGP setting is completed in both router B and router E, a sequence for establishing a BGP peer operates and a BGP peer is established (step S13). Note that this BGP peer establishment sequence conforms to a standard such as RFC.

  When an eBGP peer is established on the LSP between the router B and the router E, route information is exchanged via the eBGP peer. Here, the information of the subnet 5a advertised from the router F to the router B via the routers E, D and C in steps S1 to S4 is now established on the LSP between the router B and the router E. Advertisement is transmitted (transmitted) from the BGP protocol processing unit 201 of the router E to the BGP protocol processing unit 201 of the router B via the eBGP peer (step S14).

  When receiving the information of the subnet 5a advertised from the router E, the BGP protocol processing unit 201 of the router B registers the information in the BGP table 203 (step S15). The second line in the BGP table 203 in FIG. 3 corresponds to the registered content. Here, since the path information is exchanged via the eBGP peer directly established between the router B and the router E, the NextHop 302 is only the router E and the AS_PATH 303 is only 22.

  Then, as shown in FIG. 3, at this stage, two BGP route information are registered for the same subnet 5a. In such a case, the shorter (smaller) AS_PATH 303 is determined to be a route (shorter route) suitable for the routing topology, so the AS_PATH 303 is not the route information in the first row of two (“22” and “20”). The route information of the second row with one AS_PATH 303 (only “22”) is registered in the routing table 205.

  Then, as shown in the first line of the routing table 205b in FIG. 5B, route information in which the next hop 502 is the LSP 71 (LSP in the direction of router B → router E) is registered. In this way, traffic (packet transmission) addressed to the subnet 5a via the router B is transferred to the LSP established between the router B and the router E.

  Note that the route information on the second line in FIGS. 5A and 5B is described for comparison with the route information on the first line, and an LSP is established between the router B and the router H. Therefore, the traffic addressed to the subnet 5b via the router B is transferred to the router C (see the next hop 502).

  As described above, according to the MPLS network system in the MPLS network 1 of the present embodiment, with respect to routers straddling a plurality of ASs, only the operator sets the setting for establishing an LSP in one router, and the rest is automatic. Thus, two LSPs in opposite directions are established, an eBGP peer is established on the LSP, and traffic mapping is performed for the LSP. As a result, MPLS can be fully utilized even in a large-scale IP network, the range in which the MPLS high-speed switching technology can be applied is expanded, and a highly reliable large-scale network can be constructed. Become.

  More specifically, according to the MPLS network system in the MPLS network 1 of the present embodiment, an eBGP peer is established on two opposite LSPs between two routers across a plurality of ASs. By directly exchanging the route information between the routers at the start and end points of the LSP, it becomes possible to forward traffic to a destination that is more advantageous in routing by using the LSP to the LSP. That is, traffic mapping to LSPs existing in ASs having different start and end points can be realized by interlocking with eBGP.

This eliminates the need for static route setting in traffic mapping for LSPs across multiple ASs, and greatly improves maintenance operability. Accordingly, it becomes easy to operate a large number of LSPs across AS, that is, it is easy to apply MPLS to a large-scale network.
In addition, since BGP, which has a proven track record as an AS routing protocol, is used, traffic mapping is possible without developing a new protocol, and the impact (load and impact) on existing routers is relatively small. I'll do it.

Further, when establishing an LSP that spans an AS, it is possible to establish an LSP in both directions in the same section only by inputting a setting for establishing the LSP only in the MPLS router that is the starting point. In order to operate eBGP, reachability in both directions is required. However, according to the present embodiment, it is possible to greatly save the effort of establishing an LSP in both directions.
Furthermore, when the LSP is established, the start point MPLS router and the end point MPLS router add and exchange each other's AS number with the signaling message, so that an eBGP peer can be automatically set after the LSP is established. Generally, in BGP, it is necessary to establish a peer by specifying the IP address and AS number of the other router, but according to this embodiment, eBGP is automatically set only by inputting the LSP setting to the router. Establish peers and allow traffic mapping.

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 but may be any number as long as it is plural. In addition, the determination of superiority or inferiority (long or short) of two routes is another determination method such as giving priority to route information advertised by a BGP peer established on the LSP, instead of the number of ASs that pass through. Also good. 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 of an MPLS router. It is a block diagram of a BGP table. It is a block diagram of LSP * DB. It is a block diagram of a routing table, (a) is before LSP establishment, (b) is after LSP establishment. It is the flowchart which showed the flow of operation | movement of each router in the MPLS network of this embodiment.

Explanation of symbols

1 MPLS network 3 MPLS router 6 BGP session 71, 72 LSP
201 BGP protocol processing unit 202 RSVP protocol processing unit 205 Routing table

Claims (10)

An MPLS network system in an MPLS network including a plurality of ASs (Autonomous Systems) having one or more MPLS (Multi-protocol Label Switching) routers,
When two MPLS routers existing in different ASs among the MPLS routers are a first MPLS router and a second MPLS router,
The first and second MPLS routers are:
After establishing two LSPs (Label Switched Paths) with opposite start points, end points, and paths, the eBGP (External Border Gateway Protocol) peer is established.
Exchange route information with each other via the eBGP,
Compare the exchanged route information with the route information before establishing the eBGP peer,
An MPLS network system, wherein when the exchanged route information is shorter, the route information in its own routing table is rewritten with the exchanged route information. When establishing the eBGP peer after establishing the two LSPs between the first MPLS router and the second MPLS router,
The first MPLS router is a signaling protocol for establishing a first LSP that is the LSP in the first direction that is a direction from the first MPLS router to the second MPLS router. The identifier of the AS is added to a Path message of TE (Resource reSerVation Protocol Traffic Engineering) and transmitted to the second MPLS router,
The second MPLS router that has received the Path message adds its AS identifier to the Resv message that is a response to the Resv message and sends it back to the first MPLS router, in a direction opposite to the first direction. In order to establish a second LSP which is the LSP, a Path message with its own AS identifier added is sent to the first MPLS router;
The first MPLS router that has received the Resv message for establishing the first LSP reads the AS identifier of the second MPLS router added to the Resv message and reads the first LSP. When the Path message for establishing the second LSP is received, the AS identifier of the AS is added to the Resv message as a response to the Path message, and transmitted to the second MPLS router. Configure to establish the eBGP peer with the second MPLS router;
The second MPLS router that has received the Resv message for establishing the second LSP reads the AS identifier of the first MPLS router added to the Resv message and reads the second LSP. The MPLS network system according to claim 1, wherein a setting is made to establish the eBGP peer with the first MPLS router. In an MPLS (Multi-protocol Label Switching) network having a plurality of ASs (Autonomous Systems), MPLS routers arranged in each AS,
A routing table for storing route information;
After establishing two opposite LSPs (Label Switched Paths) with the same start point, end point, and path between the other MPLS routers existing in the AS different from the AS, the eBGP (External Border) Gateway Protocol) peer is established,
Exchanging route information with the other MPLS routers by the eBGP,
Compare the exchanged route information with the route information before establishing the eBGP peer,
If the exchanged route information is a shorter route, a BGP protocol processing unit that rewrites the route information in the routing table with the exchanged route information;
An MPLS router comprising: An RSVP protocol processing unit for performing processing related to RSVP-TE (Resource reSerVation Protocol Traffic Engineering) which is a signaling protocol for establishing the LSP;
When establishing the eBGP peer after establishing the LSP,
When it is an MPLS router that sends the first Path message that establishes the LSP,
The RSVP protocol processing unit
An identifier of the AS is added to the Path message of the RSVP-TE for establishing the first LSP which is the LSP in the first direction which is a direction from the own MPLS router to the other MPLS router. Send to the other MPLS router,
Upon receiving a Resv message as a response from the other MPLS router, the AS identifier of the other MPLS router added to the Resv message is read to establish the first LSP, and the other MPLS router When the Path message for establishing the second LSP, which is the LSP in the opposite direction to the first direction, is received from the other MPLS, the identifier of the AS is added to the Resv message as a response. Send to a router and configure to establish the eBGP peer with the other MPLS router;
When it is an MPLS router that receives the first Path message that establishes the LSP,
The RSVP protocol processing unit
When the Path message is received from the other MPLS router, a Resv message to which the AS identifier is added is returned, and the AS message is sent to the Path message for establishing the LSP in the opposite direction. Send it with an identifier,
When the Resv message is received, the AS identifier of the other MPLS router added to the Resv message is read to establish the LSP in the reverse direction, and the eBGP peer with the other MPLS router is established. The MPLS router according to claim 3, wherein a setting for performing the setting is performed. When it is an MPLS router that sends the first Path message that establishes the LSP,
The RSVP protocol processing unit
5. The MPLS router according to claim 4, wherein a process for establishing the LSP is started by using a setting input for establishing the LSP as a trigger. A path setting method in an MPLS network system of an MPLS network having a plurality of ASs (Autonomous Systems) having one or more MPLS (Multi-protocol Label Switching) routers,
Among the MPLS routers, when two MPLS routers existing in different ASs are a first MPLS router and a second MPLS router,
The first and second MPLS routers are:
After establishing two LSPs (Label Switched Paths) with opposite start points, end points, and paths, the eBGP (External Border Gateway Protocol) peer is established.
Exchange route information with each other via the eBGP,
Compare the exchanged route information with the route information before establishing the eBGP peer,
A route setting method characterized in that when the exchanged route information is shorter, the route information in its own routing table is rewritten to the exchanged route information. When establishing the eBGP peer after establishing the two LSPs between the first MPLS router and the second MPLS router,
The first MPLS router is a signaling protocol for establishing a first LSP that is the LSP in the first direction that is a direction from the first MPLS router to the second MPLS router. The identifier of the AS is added to a Path message of TE (Resource reSerVation Protocol Traffic Engineering) and transmitted to the second MPLS router,
The second MPLS router that has received the Path message adds its AS identifier to the Resv message that is a response to the Resv message and sends it back to the first MPLS router, in a direction opposite to the first direction. In order to establish a second LSP which is the LSP, a Path message with its own AS identifier added is sent to the first MPLS router;
The first MPLS router that has received the Resv message for establishing the first LSP reads the AS identifier of the second MPLS router added to the Resv message and reads the first LSP. When the Path message for establishing the second LSP is received, the AS identifier of the AS is added to the Resv message as a response to the Path message, and transmitted to the second MPLS router. Configure to establish the eBGP peer with the second MPLS router;
The second MPLS router that has received the Resv message for establishing the second LSP reads the AS identifier of the first MPLS router added to the Resv message and reads the second LSP. And setting for establishing the eBGP peer with the first MPLS router. 7. The route setting method according to claim 6, wherein the eBGP peer is established with the first MPLS router. In a MPLS (Multi-protocol Label Switching) network having a plurality of ASs (Autonomous Systems), a route setting method by an MPLS router arranged in each AS,
The MPLS router
A BGP protocol processing unit for processing related to BGP (Border Gateway Protocol);
A routing table for storing route information;
The BGP protocol processing unit
After establishing two LSPs (Label Switched Paths) with opposite start points, end points, and paths that match each other and other MPLS routers existing in the AS different from its own AS, eBGP (External BGP) ) Establish a peer,
Exchanging route information with the other MPLS routers by the eBGP,
Compare the exchanged route information with the route information before establishing the eBGP peer,
If the exchanged route information is a shorter route, the route information in the routing table is rewritten with the exchanged route information. An RSVP protocol processing unit for performing processing related to RSVP-TE (Resource reSerVation Protocol Traffic Engineering) which is a signaling protocol for establishing the LSP;
When establishing the eBGP peer after establishing the LSP,
When it is an MPLS router that sends the first Path message that establishes the LSP,
The RSVP protocol processing unit
An identifier of the AS is added to the Path message of the RSVP-TE for establishing the first LSP which is the LSP in the first direction which is a direction from the own MPLS router to the other MPLS router. Send to the other MPLS router,
Upon receiving a Resv message as a response from the other MPLS router, the AS identifier of the other MPLS router added to the Resv message is read to establish the first LSP, and the other MPLS router When the Path message for establishing the second LSP, which is the LSP in the opposite direction to the first direction, is received from the other MPLS, the identifier of the AS is added to the Resv message as a response. Send to a router and configure to establish the eBGP peer with the other MPLS router;
When it is an MPLS router that receives the first Path message that establishes the LSP,
The RSVP protocol processing unit
When the Path message is received from the other MPLS router, a Resv message to which the AS identifier is added is returned, and the AS message is sent to the Path message for establishing the LSP in the opposite direction. Send it with an identifier,
When the Resv message is received, the AS identifier of the other MPLS router added to the Resv message is read to establish the LSP in the reverse direction, and the eBGP peer with the other MPLS router is established. The route setting method according to claim 8, wherein a setting for performing the setting is performed. When it is an MPLS router that sends the first Path message that establishes the LSP,
The RSVP protocol processing unit
10. The path setting method according to claim 9, wherein a process for establishing the LSP is started using a setting input for establishing the LSP as a trigger.

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