WO2008031334A1

WO2008031334A1 - Route updating method, system and router

Info

Publication number: WO2008031334A1
Application number: PCT/CN2007/070183
Authority: WO
Inventors: Renhai Zhang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-09-07
Filing date: 2007-06-26
Publication date: 2008-03-20
Also published as: CN101141382A

Abstract

A route updating method is provided. When route notification is being performed, a first router sends information of multiple routes towards the same destination address to a second router. Said second router adds routes according to the received multiple-route information. There is relationship of neighbor between the first router and the second router. When route withdrawing is being performed, said first router sends withdrawing route next hop information to the second router, and said second router withdraws routes according to received withdrawing route next hop information. A route updating system and a router are further provided.

Description

Route update method, system and router

The present application claims priority to Chinese Patent Application No. 200610127202.8, entitled "Routing Update Method and Router", filed on September 7, 2006, the entire contents of which is incorporated herein by reference.

Technical field

The present invention relates to the field of data communication technologies, and in particular, to a route update method, system, and router.

Background technique

The Border Gateway Protocol (BGP) is a dynamic route discovery protocol between ASs (Autonomous Systems). Its basic function is to automatically exchange loop-free routing information between autonomous systems. Corresponding to protocols running within the autonomous region, such as Open Shortest Path First (OSPF) and Routing Information Protocol (RIP), BGP is an external gateway protocol (EGP). OSPF and RIP are the Interior Gateway Protocol (IGP).

There are two types of BGP connections, IBGP (Intemal BGP, Internal Border Gateway Protocol) and

EBGP (External BGP, External Border Gateway Protocol). A BGP connection established in the same AS autonomous area is called IBGP. The BGP connection between different ASs is an EBGP connection.

A BGP router running in the same AS autonomous system requires full connectivity because of the protocol function and mechanism constraints, that is, any two routers running BGP must have an IBGP connection. The two routers that establish an IBGP connection are neighbors. The IBGP connection is a TCP connection, not a physical connection. The requirement is high and the complexity is N square. For example, if there are N routers in an autonomous system, if the connection is full (that is, a BGP connection is established between each two routers) , you need to establish N ( N-1 ) /2 IBGP connections. The application of the RR (Router Reflector) effectively reduces the number of IBGP neighbors established.

Please refer to FIG. 1 , which is a topology diagram of a route reflector network in the prior art. The concept of route reflector networking is to divide the router running BGP protocol in an autonomous system into RR101, client 102 and non-client 103. According to the reflector protocol, the non-client 103 and the route reflector 101 in the autonomous system remain fully connected, and the IBGP-based neighbor relationship must be established between the client 102 and the reflector 101. The route advertisement policy is: the route reflector 101 sends the client 102 The routing information is sent to the other client 102 and the non-client 103, and the routing information sent by the non-client 103 is sent to all the clients 101.

Please refer to FIG. 2, which is a schematic diagram of a network using a border gateway protocol in the prior art. On the access side, for the robustness of the network, the user usually establishes two paths with the backbone network and accesses different routers in the backbone network to provide redundant backup. The CE (Customer Edge) router 205 is connected to the carrier backbone network through the PE (Provider Edge) 1 router 202 and the PE2 router 203. To reduce the number of BGP neighbors, one router in the backbone network is configured as a route reflection. The PE1 router 202, the PE2 router 203, and the PE3 router 204 are all clients of the route reflector 201. The route reflector 201 and the three clients are configured with a BGP connection-based neighbor relationship; however, no configuration is required between the clients, such as the PE1 router 202 and the PE3 router 204, the PE2 router 203, and the PE3 router 204. Neighbor relationship based on BGP connection. After receiving the routing information of the client from the PE1 router 202 and the PE2 router 203, the route reflector 201 selects one of the optimal routing information and sends it to the PE3 router 204 according to the BGP routing rule. Thus, the traffic sent from the PE3 router 204 to the user autonomous system AS65535 can only go to one of the two routes PE3 router 204 - PE1 router 202 - CE router 205 or PE3 router 204 - PE2 router 203 - CE router 205, so it cannot Implement load sharing.

In addition, when a route failure occurs, the route reflector 201 needs to resend another route information to the PE3 router 204, thereby implementing route convergence, and then the service can be restored, so that fast handover when the route failure cannot be implemented.

Summary of the invention

The embodiments of the present invention provide a route update method, system, and router, which provide implementations for load balancing or fast handover of routes, thereby improving network operation quality.

The embodiment of the present invention provides a route update method, in which the first router sends multiple routing information to the second router to the same destination address, and the second router receives the multiple routing information according to the received routing information. Adding a route, the first router and the second router have a neighbor relationship; when the route is revoked, the first router sends the revoked next hop information to the second router, and the second router receives the The revocation route next hop information is revoked.

The embodiment of the present invention further provides a router, including: a neighbor relationship establishing unit, configured to establish a neighboring relationship with the other routers, where the other routers include at least a second router, and a route update information sending unit, configured to: when the route advertisements, the second relationship that has been established by the neighbor relationship establishing unit The router sends multiple routing information to the same destination address; and when the route is revoked, sends the revoked next hop information to the second router.

The embodiment of the present invention further provides a routing update system, which includes at least a first router and a second router that have a neighbor relationship with each other, and the first router sends the same to the second router when the route advertisement is performed. a plurality of routing information of the destination address, where the second router adds a route according to the received multiple routing information; when the first router performs routing revocation, sends the second hop information of the revoked route to the second router. The second router revokes the route according to the received revocation route next hop information.

It can be seen from the above technical solution that, in the embodiment of the present invention, the first router sends multiple routing information to the second destination router that has the neighbor relationship with the same destination address, so that the second router can maintain the same destination address. When the route is revoked, the first router may send the revoked next hop information to the second router, so that the second router can quickly switch traffic to other unfailed routes. It can be seen that the technical solution provided by the embodiment of the present invention can improve the network operation quality by providing load balancing or fast handover for routing. DRAWINGS

1 is a topology diagram of a route reflector network in the prior art;

2 is a schematic diagram of a network using a border gateway protocol in the prior art;

3 is a schematic flowchart of an embodiment of a route update method according to the present invention;

4 is a schematic structural diagram of an embodiment of a router in the present invention;

FIG. 5 is a schematic diagram of an embodiment of a route update system according to the present invention.

detailed description

In the embodiment of the present invention, before the route advertisement, the routers perform capability negotiation to establish a neighbor relationship. When the route advertisements, the router sends at least the neighboring routers (the neighbor routers) to the same destination address. Two routing information (ie, multiple routing information); when the route is revoked, the router sends the revoked next hop information to the neighboring router, and the neighboring router performs routing update according to the received information. Please refer to FIG. 3 , which is a schematic flowchart of a route update method according to the present invention.

Step 301: Before the route advertisement, the routers can advertise the capability of processing the multi-route information to the same destination address, perform capability negotiation, and establish a BGP-based neighbor relationship. The ability to process the multi-route information specifically includes the ability to advertise, identify, and revoke the ability to revoke the next hop information of the route.

According to the BGP rule, the router that supports the capability advertisement carries the capability parameter in the OPEN (open) packet when the connection is established with the peer router. The peer router determines whether the capability supported by the peer router is related to the local end according to the received parameters. The router matches. If the inconsistency, that is, the local router does not support some of the capabilities, the NOTIFICATION message is sent to the peer router to notify the peer router that the local router does not support the capability. After receiving the information, the peer router resends the OPEN. A packet carrying only the capability parameters supported by the peer router.

The OPEN packet is mainly used to establish a neighbor relationship, and is an initial handshake information between routers running BGP. Before sending any other advertisement information, the OPEN packet can be used to exchange the BGP version and the AS number (AS number). The BGP capability parameters can also be negotiated through the OPEN packet by the information such as the hold time of the adjacency relationship, the local router ID, the BGP identifier, and the capability advertisement. After receiving the OPEN message, the router at the receiving end responds with the KEEPALIVE message. Once the handshake is successful, the routers that are neighbors will perform UPDATE (update).

The KEEPA LIVE message is mainly used to implement the connection reliability confirmation between the neighboring routers. Since it is only used to confirm the neighbor relationship, it does not have a packet body only the packet header. After the router establishes a neighbor relationship, it sends the KEEPALIVE packet to the neighboring router periodically according to the set time. The interval is 60 seconds by default.

The NOTIFICATION packet is used to perform an error notification when detecting an error in the BGP connection relationship. This error may be artificial or systemic, including connection interruption and OPEN message negotiation error. When the router finds that the BGP connection relationship is in error, it sends a NOTIFICATION message to the neighbor router.

The relevant field format of the negotiation capability parameter in OPEN^ is as follows: Capability Code (1 byte)

Capability Length (1 byte)

Capability Value where:

Capability Code: Capability Code information, the specific content of the Capability Code field needs to be applied to an official agency, such as IANA, with a Capability Length of 4 bytes. The contents of Capability Value are defined as follows:

AFI Res. SAF1

AFI: Address family information, which identifies which protocol address family supports this feature;

Res: reserved field;

SAFI: Subaddress family information.

Capability Length: The length of the capability parameter value field;

Capability Value: The value of the capability, which is parsed according to the Capability Code information. Each capability negotiation may be carried by the OPEN message to carry one or more of the foregoing capability parameter related information, and each capability parameter represents a capability. Specifically, different "Capability Code" represents different types of capability parameters.

Referring to the related field format of the foregoing existing capability parameters, the embodiment of the present invention augments the type of the existing capability parameter, and adds a new type of capability parameter, that is, applies for a new "Capability Code", which is used to indicate a negotiation process for multiple routes. The ability parameter of the information. Specifically, when a connection is established, the router that needs to establish a neighbor relationship uses the new type of capability parameter in the OPEN packet, and notifies the other party of the capability of processing the multi-route information to the same destination address, thereby performing the type capability. Negotiation.

Step 302: When the route is advertised, the router sends at least two pieces of routing information to the neighboring router to the same destination address, and the neighboring router adds a route according to the information.

The sending router uses the UPDATE message to send the learned routing information to the neighboring router. Compared with the routing information sent in the prior art, the routing information sent in the embodiment of the present invention does not need to add a new attribute. The UPDATE message is used to advertise routing information between routers that are neighbor relationships. It includes three parts: unreachable (unreachable) and path attributes (path attributes). NLRI (network layer reachability information) „ UPDATE messages can advertise a route and can also revoke multiple unreachable routes.

When there are at least two (ie, multiple) routes that arrive at the same destination address and have different next hops, the router selects one route from each next hop, and then sends the neighboring router to the same destination address. Multiple routing information.

Step 303: When the route is revoked, the router sends the next hop information of the revoked route to the neighboring router, and the neighboring router revokes the route according to the next hop information of the revoked route carried by the information.

The sender router notifies the receiver router of the next hop information of the revoked route (that is, the route that needs to be revoked), so as to specify the route to be revoked. In the embodiment of the present invention, a field is newly added in the UPDATE message to carry the next hop information of the route to be revoked. The specific content of the UPDATE message in the embodiment of the present invention is as follows:

Revoke route length

Revoke the next hop of the route

Revoke the routing destination address

Path attribute length

Path attribute

Network Layer Reachability Information (NLRI) Compared with the existing UPDATE message, the second line in the UPDATE message content (the next hop of the revocation route) is the newly added content. When revoked, the UPDATE message may not carry the last three lines of information. In this way, after receiving the packet, the receiving router can find the route in the routing table according to the revocation route destination address and the revocation route next hop information, and perform the revocation operation. It should be noted that, in the case that the router itself fails, and all the routes through the faulty router are invalid, the sending router may not send the revoked routing destination address to the receiving router, and only send the retracing next hop information. Further, the receiving end router revokes all routes passing through the faulty router (ie, the router represented by the revoked next hop information) according to the revoked next hop information.

The following is still an example of the embodiment of the present invention. The network shown in Figure 2 A route reflector 201 is included, as well as a PE1 router 202, a PE2 router 203, and a PE3 router 204 as clients of the route reflector 201.

The route reflector 201 establishes a connection with the PE1 router 202, the PE2 router 203, and the PE3 router 204, and negotiates the multi-route processing capability to the same destination address and the ability to process the next hop information carrying the revoked route, thereby establishing a BGP-based Neighbor relationship.

At the time of the route advertisement, the route reflector 201 sends the two routing information that it knows to reach the same destination address to the PE3 router 204, and the two routing information are: PE 1 router 202 - CE router 205; and PE3 Router 204 - PE2 router. Thus, PE3 router 204 will know that there are two routes to AS65535: (1) PE3 router 204 - PE 1 router 202 - CE router 205; (2) PE3 router 204 - PE2 router 203 - CE router 205. At this time, the traffic of the PE3 router 204 to the AS65535 may be partially routed (1), that is, the PE3 router 204 sends the part of the traffic from the outbound interface connected to the PE1 router 202; the other part takes the route (2), that is, the PE3 router 204. This part of the traffic is sent out from the outbound interface connected to the PE2 router 203. It can be seen that the route reflector 201 sends two routing information to the PE3 router 204 to the same destination address, so that the PE3 router 204 can send traffic to the destination address through two routes, thus implementing load balancing of the traffic.

A person skilled in the art can understand that after the PE3 router 204 receives two routing information from the route reflector 201 to the same destination address, and adds a route according to the information, the two routing information can be sent to the same destination address through the two routing information. Traffic is used to implement load balancing. It is also possible to perform load balancing without just performing load balancing. Therefore, you can implement fast switching in the event of a fault. The following is a detailed introduction to JH. The reflector 201 sends two routing information to the PE3 router 204 during the previous route advertisement. Therefore, the PE3 router 204 and the PE3 router 204 - PE2 router 203 - CE router 205 remain in communication. Then, the route reflector 201 sends the route revocation next hop information (which may also include the revocation route destination address) to the PE3 router 204, and the revocation route next hop information refers to the PE 1 router 202, and then all passes through the PE1 router 202. The route will be invalid. After receiving the next hop information of the revoked route from the route reflector 201, the PE3 router 204 can send all the traffic that is sent through the PE3 router 204 - PE 1 router 202 - CE router 205. Switch to PE3 router 204 - PE2 router 203 - CE router 205 to send this route, so that traffic will not be interrupted, protect user services from being affected, implement route backup, and improve network operation quality.

It can be seen from the foregoing embodiment and the specific implementation manner that the technical solution provided by the embodiment of the present invention provides multiple routing information to the neighboring router to reach the same destination address, and provides load sharing and fast handover for the network system using BGP. Implement ^5 out. Further, by introducing a new optional capability advertisement to identify such processing capability of the router and negotiating through the existing capability negotiation mechanism of BGP, seamless backward compatibility can be achieved for existing devices. It should be noted that, although the specific embodiment shown in FIG. 2 is described by taking a network including a route reflector as an example, those skilled in the art should understand that the technical solutions provided by the embodiments of the present invention can also be applied to Set up the route reflector in the network.

A person skilled in the art may understand that all or part of the steps in implementing the above method embodiments may be completed by a program instructing related hardware, and the program may be stored in a computer readable storage medium, the storage medium Such as: ROM / RAM, disk, CD, etc.

Please refer to FIG. 4, which is a schematic structural diagram of a router embodiment using a border gateway protocol according to the present invention. The router 400 in this embodiment includes a neighbor relationship establishing unit 401, a route update information sending unit 402, and a routing table unit 403. The units are described in detail below.

The neighbor relationship establishing unit 401 is configured to establish a neighbor relationship with other routers based on BGP before the route advertisement. For convenience of description, it is assumed that the other routers include at least a second router. In order to be compatible with the BGP existing capability negotiation mechanism, the multi-route capability negotiation unit may be configured in the router 400, and the capability for negotiating and processing multiple routing information to the same destination address in the process of establishing the neighbor relationship by the neighbor relationship establishing unit 401 . It can be understood by those skilled in the art that if the BGP existing capability negotiation mechanism is not compatible, the multi-routing capability negotiation unit may not be set. For example, in the case that all routers have multi-route related processing capability, between routers It is also possible not to negotiate this capability.

The routing update information sending unit 402 is configured to: when the route advertisement is used, to the second router that has established the neighbor relationship by the neighbor relationship establishing unit 401 (since the router 400 has established a neighbor relationship with the second router, the two Sending multiple routing information to the same destination address for the neighboring router; and sending the next hop information of the revoked route to the second router when the route is revoked (eg, If necessary, you can also send the revocation route destination address information).

The routing table unit 403 is configured to: when receiving, by the other routers that have established the neighbor relationship by the neighbor relationship establishing unit 401, specifically the routing update information sending unit of the other router, multiple routing information that arrives at the same destination address Adding a route according to the information; and when receiving the revoked next hop information sent by another router (specifically, the route update information sending unit of the other router) that has established the neighbor relationship by the neighbor relationship establishing unit 401, The route is revoked according to the revocation route next hop information carried by the information.

It should be noted that, if the router 400 in the foregoing embodiment is only used as a route reflector, it may include only the neighbor relationship establishing unit 401 and the route update information sending unit 402; if the router is considered to be placed in a specific application environment, it may not be If the router is to be used as a route reflector or a normal router (such as the role of the PE3 router 204 in FIG. 2), the neighbor relationship establishing unit 401 and the route update information sending unit 402 may be set in the router 400 at the time of production. A routing table unit 403 is set. In this way, the router 400 can be configured as a route reflector or as a normal router.

Please refer to FIG. 5 , which is a schematic diagram of a route update system disclosed by the present invention. The routing update system in this embodiment includes at least a first router and a second router that have a neighbor relationship based on each other. The first router sends multiple routes to the second router to the same destination address when performing route advertisement. Routing information, the second router adds a route according to the received multiple routing information; the first router sends the revoked next hop information to the second router when the route is revoked, the second The router revokes the route according to the received next hop information of the revoked route. If the routing update system shown in this embodiment corresponds to the specific application environment shown in FIG. 2, the first router in the embodiment of the system corresponds to the route reflector 201 in FIG. 2, and the second router corresponds to FIG. 2. In the PE3 router 204.

Specifically, the first router includes a first neighbor relationship establishing unit 501, a route update information sending unit 502, and a first multi-routing capability negotiating unit 503; the second router includes a second neighbor relationship establishing unit 504, and a routing table. Unit 505 and second multi-routing capability negotiation unit 506. The internal structure and connection relationship of the system are further introduced below in conjunction with the working principle of the system.

First, the first router establishes a neighbor relationship with other routers based on the BGP by the first neighbor relationship establishing unit 501, and the other routers at least include the second router. Technical person It can be understood that the establishment of the neighbor relationship is mutual. Therefore, the establishment of the neighbor relationship between the first and second routers is mainly performed by the first neighbor relationship establishing unit 501 and the second neighbor relationship establishing unit 504.

If compatibility with the BGP existing capability negotiation mechanism is considered, a first multi-routing capability negotiation unit 503 may be set in the first router, and a second multi-routing capability negotiation unit 506 may be set in the second router. The two multi-routing capability negotiation units are configured to: when the first neighbor relationship establishing unit 501 and the second neighbor relationship establishing unit 504 establish a neighbor relationship between the first and second routers, the negotiation process reaches the same destination address. The ability to multi-route information.

Then, when the first router has established the neighbor relationship with the second router by the first neighbor relationship establishing unit 501, the first router sends the same to the second router through the route update information sending unit 502 when the route advertisement is advertised. Multiple routing information of the destination address. There are usually many routers in a network system. Therefore, the first router may also establish a neighbor relationship with other routers other than the second router through the first neighbor relationship establishing unit 501, thereby obtaining information from the other routers. The routing information, if it is found that there are multiple routing information that arrives at the same destination address through the learned routing information, the routing information sending unit 502 can send the multiple routing information to the second router. It can be understood that the multiple pieces of routing information sent may be all routing information that is learned by the first router and reach the same destination address, or may be only part of the routing information. In addition, when the route is revoked, the first router also sends the revoked next hop information to the second router by using the route update information sending unit 502 (and may also include the revoked destination address information if necessary).

After the second router receives the information of the first router that has established the neighbor relationship by the second neighbor relationship establishing unit 504, the second router performs processing by the routing table unit 505. Specifically, when receiving the plurality of pieces of routing information of the same destination address sent by the routing update information sending unit 502 of the first router, the routing table unit 505 adds a route according to the multiple routing information; When the route revoke information sending unit 502 sends the revoked next hop information, the routing table unit 505 revokes the route according to the revoked next hop information. The principles and embodiments of the present invention have been described in terms of specific examples, and the description of the above embodiments is only to assist in understanding the method of the present invention and its core concepts. Also, to those skilled in the art, In view of the above, the description of the present invention is not limited to the scope of the present invention.

Claims

Rights request

A method for updating a route, comprising:

When the route is advertised, the first router sends multiple routing information to the second router to the same destination address, and the second router adds a route according to the received multiple routing information, the first router and the second router. There is a neighbor relationship between them;

When the route is revoked, the first router sends the revoked next hop information to the second router, and the second router revokes the route according to the received revoked next hop information.

The method according to claim 1, wherein the sending, by the first router, the multiple routing information to the second router to the same destination address includes:

When the first router learns that there are multiple routes that arrive at the same destination address and have different next hops, the first router selects one route from each next hop, and sends the selected one to the second router. Multiple routing information.

The method according to claim 1, wherein before the routing advertisement, the method further includes: establishing, by the first router and the second router, a neighbor relationship, establishing at the first router and the second router The process of the neighbor relationship further includes:

The first router negotiates with the second router for the capability of processing multiple routing information to the same destination address.

The method according to claim 1, wherein the first router sends the destination address information of the revoked route while sending the revoked next hop information to the second router.

The method according to any one of claims 1 to 4, wherein the adding, by the second router, the route according to the received multiple routing information further comprises:

The second router sends traffic to the same destination address through the multiple routes, and performs load sharing.

The method according to any one of claims 1 to 4, wherein, after the second router revokes the route according to the received revocation route next hop information, the method further includes:

The second router switches the traffic sent by the revocation route to another route that reaches the same destination address for sending.

The method according to any one of claims 1 to 4, wherein the first router is a route reflector.

The method according to any one of claims 1 to 4, wherein the neighbor relationship existing between the first router and the second router is a neighbor relationship established based on the border gateway protocol BGP.

9. A router, comprising:

a neighbor relationship establishing unit, configured to establish a neighbor relationship with other routers, where the other routers include at least a second router;

a routing update information sending unit, configured to: when routing advertisements, send, to the second router that has established a neighbor relationship by the neighbor relationship establishing unit, multiple routing information that arrives at the same destination address; and when the route is revoked, The second router sends the revocation route next hop information.

The router according to claim 9, further comprising:

The multi-routing capability negotiation unit is configured to negotiate the capability of processing the multi-route information to the same destination address in the process of establishing the neighbor relationship by the neighbor relationship establishing unit.

The router according to claim 9 or 10, further comprising: a routing table unit, configured to: when receiving the same destination address sent by another router that has established a neighbor relationship by the neighbor relationship establishing unit When a plurality of pieces of routing information are added, the route is added according to the data; and when the next hop information of the revoked route sent by the other routers that have established the neighbor relationship by the neighbor relationship establishing unit is received, the route is revoked accordingly.

The router according to claim 9 or 10, wherein the neighbor relationship established by the neighbor relationship establishing unit is specifically a neighbor relationship established based on BGP.

A routing update system, comprising at least a first router and a second router having a neighbor relationship with each other, wherein:

The first router sends multiple routing information to the second router to the same destination address when the route advertisement is performed, and the second router adds a route according to the received multiple routing information.

The first router sends the revoked next hop information to the second router when the route is revoked, and the second router revokes the route according to the received revoked next hop information. Z 5

WO 2008/031334 PCT/CN2007/070183

- 14-

The system according to claim 13, wherein the first router comprises: a first neighbor relationship establishing unit, configured to establish a neighbor relationship with other routers, where the other routers include at least a second router ;

a routing update information sending unit, configured to: when routing advertisements, send, to the second router that has established a neighbor relationship by using the first neighbor relationship, a plurality of routing information that arrives at the same destination address; and When the data is revoked, the next hop information of the revoked route is sent to the second router.

The system according to claim 13 or 14, wherein the second router comprises:

a second neighbor relationship establishing unit, configured to establish a neighbor relationship with another router, where the other router includes at least the first router;

a routing table unit, configured to: when receiving the multiple routing information that is sent by the first router that has established the neighbor relationship by the second neighbor relationship establishing unit to reach the same destination address, increase the route according to the When the next hop information of the revocation route sent by the first router is sent, the route is revoked accordingly.

The system according to claim 15, wherein each of the first router and the second router further comprises:

a multi-routing capability negotiation unit, configured to: when the first neighbor relationship establishing unit and the second neighbor relationship establishing unit establish a neighbor relationship between the first and second routers, the negotiation process reaches the same destination address The ability to multi-route information.

The system according to claim 13 or 14, wherein the first router is a route reflector.