WO2008098493A1

WO2008098493A1 - A method for aggregating routes, a method for forwarding messages and an autonomous system border router

Info

Publication number: WO2008098493A1
Application number: PCT/CN2008/070201
Authority: WO
Inventors: Yong Li
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-02-09
Filing date: 2008-01-28
Publication date: 2008-08-21
Also published as: CN101014014A; CN100596107C

Abstract

The present invention provides a route aggregation method which is applied to a network comprising at least one Autonomous System Border Router (ASBR), each ASBR is connected to at least one Provider Edge (PE), the method includes: the ASBR receiving a plurality of original routes from the PE, aggregating the original routes which have a same Route Distinguisher (RD) and belong to a same sub-network, generating aggregated routes, distributing a label to each aggregated route, and adding the label into the aggregated route, generating an aggregated route with the label. The routes which are received and stored by the Autonomous System Border Router are reduced by using the present invention, and the burden of forwarding the routes is also reduced. Simultaneously, the present invention also provides a method for forwarding messages and an Autonomous System Border Router, and the routes which are received and stored by the Autonomous System Border Router are effectually reduced, so as to reduce the number of the routes in the whole network.

Description

Route aggregation method, message forwarding method, and autonomous system border router

The present invention relates to a routing protocol technology in the field of data communication, and specifically relates to a method for implementing route aggregation in a Border Gateway Protocol/Multiple Protocol Label Switching Virtual Private Network (BGP/MPLS VPN). Packet forwarding method and autonomous system border router. Background of the invention

BGP/MPLS VPN is a mechanism that allows a service provider (SP) to use its own backbone network to provide customers with virtual private network (VPN) services. BGP/MPLS VPN uses the Border Gateway Protocol (BGP) protocol to advertise VPN routes on the service provider backbone network and forward VPN packets on the service provider backbone network using the MPLS (Multi Protocol Label Switch) protocol. . The MPLS protocol is a protocol for forwarding MPLS packets by using labels in MPLS packets. The VPN packets also belong to MPLS packets.

Figure 1 shows the block diagram of the BGP/MPLS VPN network model. As shown in FIG. 1, the BGP/MPLS VPN includes: a User Edge Device (CE) 101, a Provider Edge (PE) 102, and a Service Provider Router (P, Provider) 103. among them,

CE101 is used to connect user sites to the SP backbone network.

PE102 is an edge device of the SP backbone network and is directly connected to the CE. In a BGP/MPLS VPN network, all VPN information is processed on the PE. A VPN routing forwarding forwarding instance (VRF, VPN Routing & Forwarding Instance) is stored on the PE. The VPN instance contains routing tables and forwarding tables. The VPN packet arriving at PE102 can be based on the phase. The VPN instance should be forwarded.

P103 is the backbone router of the SP backbone network. It only needs to be responsible for forwarding VPN packets and does not need to maintain VPN information.

Before BGP/MPLS VPN is used for packet forwarding, firstly, each PE 102 exchanges VPN routes, that is, routes are advertised to ensure the uniformity of routing between PEs. Since a user site can belong to multiple VPNs, the IP address of the user site can belong to multiple VPNs. Therefore, the VPN route uses the route distinguisher (RD, Route Distinguisher) to indicate which VPN the VPN route comes from. The IP address in the VPN route consists of the RD and IPv4 address prefixes/masks, so the VPN route is also called VPN-IPv4 route.

When a PE distributes a VPN-IPv4 route using BGP, it uses itself as the next hop node and assigns and distributes a label for the VPN-IPv4 route. In the case that the current number of VPNs and the number of routes to the user sites of each VPN are large, the number of routes received and saved by the PE will be very large. To solve this problem, VPN-IPv4 routes are currently aggregated on the PE. Route aggregation is a method of merging multiple original routes into one aggregated route and using a single aggregate address to represent a series of network numbers. The route aggregation method on the PE can reduce the number of routes sent by PEs to other PEs, thus reducing the amount of route storage on each PE.

An autonomous system is a group of routers and networks under the control of a regulatory agency. In an actual networking application, when the SP backbone network is provided by more than one management organization, the VPN spans multiple autonomous systems, and an inter-domain VPN is formed. For inter-AS VPNs, PEs belonging to different autonomous systems can exchange VPN routes through the Autonomous System Border Router (ASBR) of their respective ASs. Summary of the invention

The embodiment of the present invention provides a route aggregation method, where the route aggregation method is applied to a network including at least one ASBR, and the ASBR is connected to at least one PE, and the method includes:

The ASBR receives multiple original routes from the PE, aggregates the original routes of the same subnet with the same route distinguisher (RD), generates an aggregated route, assigns a label to each aggregated route, and adds the label to the aggregated route. The label generates an aggregated route carrying the label.

The embodiment of the present invention provides a packet forwarding method, where the packet forwarding method is applied to a network including at least one ASBR, and the ASBR is connected to at least one PE, and the method includes:

The first ASBR receives at least one original route from the at least one PE, aggregates the original routes that belong to the same subnet, and generates an aggregated route, and assigns a label to each aggregated route, and joins the aggregated route. The label generates an aggregated route carrying the label;

And storing the corresponding relationship between the label allocated to the aggregation route and the original route corresponding to the aggregation route; and the advertised route carrying the label is advertised to the second ASBR of another autonomous system; the first ASBR receives the The packet carrying the packet sent by the second ASBR obtains the corresponding original route from the corresponding relationship according to the label carried in the packet; and obtains the packet forwarding route from the obtained original route; The forwarding route forwards the packet.

The embodiment of the invention further provides an autonomous system border router, which can reduce the received and saved routes and reduce the burden of routing and forwarding.

The ASBR is applied to a network including multiple ASBRs, and each ASBR is connected to multiple PEs, where the ASBR includes a route aggregation processing unit and a label allocation unit. The route aggregation processing unit is configured to receive a plurality of original routes from multiple PEs, and aggregate the original routes that belong to the same subnet, and generate an aggregation route, and send the aggregation route to the label distribution unit.

The label allocating unit is configured to allocate a label for each aggregated route received from the route aggregation processing unit, and add the label to the aggregated route to generate an aggregated route carrying the label.

Compared with the prior art, the route aggregation method, the packet forwarding method, and the autonomous system border router provided by the embodiment of the present invention perform aggregation processing and label distribution on the ASBR on the VPN-IPv4 route received from the PE. The ASBR advertises only the aggregated routes to the ASBRs of other ASs. Correspondingly, the ASBRs of other autonomous systems only advertise the aggregated routes to the ASBRs of the local AS. Therefore, the route received and saved by the ASBR is effectively reduced, the burden of routing and forwarding is reduced, and the problem of insufficient routing capacity of the ASBR is solved. At the same time, the reduction of routes reduces the number of labels allocated for routes, which greatly saves label resources. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the block diagram of the BGP/MPLS VPN network model.

FIG. 2 is a schematic diagram of an application scenario according to an embodiment of the present invention.

FIG. 3 is a flowchart of a method for a route aggregation method according to an embodiment of the present invention.

FIG. 4 is a flow chart of a method for implementing packet forwarding by using the route aggregation method of FIG. 3.

FIG. 5 is a flow chart of another embodiment of implementing packet forwarding by using the route aggregation method of FIG. 3.

FIG. 6 is a flow chart showing an example of the message forwarding method of FIG. 5.

FIG. 7 is a schematic structural diagram of a first embodiment of an autonomous system border router according to the present invention. FIG. 8 is a schematic structural diagram of a second embodiment of an autonomous system border router according to the present invention. Mode for carrying out the invention

The embodiments of the present invention will be further described in detail below with reference to the embodiments and the accompanying drawings.

FIG. 2 is a schematic diagram of an application scenario according to an embodiment of the present invention. The block diagram of the cross-domain BGP/MPLS VPN network model is shown in Figure 2. The AS (Autonomous System) 100 and AS200 are two autonomous systems. PE-1, PE-2, and ASBR-1 belong to AS100. PE-3, PE-4 and ASBR-2 belong to AS200. PEs that belong to different ASs need to be routed through the ASBR.

For example, when PE-1 advertises a route to PE-3, the VPN-IPv4 route carrying the label is sent to PE-3 through ASBR-1 and ASBR-2. Both ASBR-1 and ASBR-2 store and re-specify the processing of the next hop node and label in the received VPN-IPv4 route. It can be seen that for the inter-AS VPN, the ASBR aggregates the VPN-IPv4 routes sent by all the PEs in the AS, and the ASBR is responsible for receiving and storing the VPN-IPv4 routes sent by all the PEs of the AS. It is advertised to the ASBRs of other ASs. It also receives and saves the VPN-IPv4 routes advertised by the ASBRs of other ASs and advertises them to the PEs of the AS. Therefore, the ASBR has high storage and forwarding capacity. However, the existing aggregation of routes on the PE can only reduce the number of VPN-IPv4 routes advertised by each PE to the ASBR to a certain extent. The number of VPN-IPv4 routes that need to be stored and processed on the ASBR is still very large when the number of PEs in the entire network is large and the number of VPNs and the number of user sites per VPN are large. When an operator establishes a large-scale cross-domain VPN network, the ASBR will have problems such as insufficient routing capacity, insufficient label resources, and excessive forwarding burden.

In a cross-domain VPN, the PE only maintains the routes of the VPNs connected to it. Therefore, the VPN-IPv4 routes received by the ASBR from different PEs may come from the same VPN and still belong to the same subnet, so there is a possibility of further aggregation. But the prior art is not on the ASBR. The VPN-IPv4 routes that may also be aggregated are aggregated, but all received VPN-IPv4 routes are advertised to other autonomous systems.

Therefore, in the embodiment of the present invention, on the ASBR, the original routes that belong to the same subnet are aggregated according to the original routes received from the multiple PEs to generate an aggregation route, and each aggregation route is assigned a label and is aggregated. The label is added to the route to generate an aggregated route carrying the label. This reduces the number of routes that the ASBR advertises to other ASBRs. FIG. 3 is a flowchart of a method for a route aggregation method according to an embodiment of the present invention. The method specifically includes the following two steps:

Step 301: The ASBR receives multiple original routes from multiple PEs, and aggregates the original routes that belong to the same subnet and generates an aggregated route.

In this step, route aggregation is a method in which multiple VPN-IPv4 routes with the same RD and IPv4 address prefix/mask belong to the same subnet, that is, original routes, are aggregated and merged into one aggregation route. Route aggregation can use the aggregation algorithm defined by BGP. The VPN-IPv4 routes sent by the PE include attribute information such as RD, IPv4 address prefix/mask, route target (RT, Route Target), next hop node, and outgoing label. Therefore, the aggregated route needs to inherit the attribute information of the original route. During the aggregation process, the RD of the aggregated route, the IPv4 address before the mask, and the RT are determined according to the original route. The next hop of the aggregated route is the ASBR itself. The outgoing label of the aggregated route is specified by the ASBR.

The aggregation process includes: If the IPv4 address prefix/mask of the original route belongs to the same subnet, the ASBR will pre-address multiple IPv4 addresses belonging to the same subnet according to the RD and IPv4 address prefix/mask of the original route. And merging into a short masked IPv4 address before the 3/4/mask, and determining the merged IPv4 address prefix/mask as the pre-mask of the IPv4 address of the aggregated route; determining the RD of the original route as the RD of the aggregated route; Determine the RT of the aggregated route based on the RT of the original route. Step 302: The ASBR allocates an inbound label to each of the aggregated routes, and adds the inbound label to the aggregated route to generate an aggregated route that carries the inbound label.

The inbound label assigned to the aggregated route in this step is the outgoing label specified by the ASBR for the aggregated route. For the ASBR, the label carried in the original route received from the PE is the outgoing label, and the label allocated for the aggregated route is the incoming label. When the ASBR advertises the advertised route, the ASBR that receives the advertised route carries the label. Therefore, the following describes the labeling of the aggregated route, the outgoing label carried by the aggregated route, and the incoming label carried by the aggregated route.

At this point, the route aggregation on the ASBR is completed.

FIG. 4 is a flow chart of a method for implementing packet forwarding by using the route aggregation method of FIG. 3. Referring to FIG. 4, the method specifically includes the following steps:

Step 401: The ASBR receives multiple original routes from multiple PEs, and aggregates original routes that belong to the same subnet and generates aggregated routes.

Step 402: Assign an inbound label to each aggregation route, and add the ingress label to the aggregation route to generate an aggregation route carrying the label.

Step 403: Store the correspondence between the inbound label allocated to the aggregated route and the original route corresponding to the aggregated route.

Step 404: Publish the aggregated route carrying the inbound label allocated to the ASBR of the other autonomous system.

Step 405: The ASBR obtains the original route corresponding to the carried label of the VPN packet according to the correspondence between the inbound label and the original route that is stored in the ASBR, when the ASBR receives the VPN packet carrying the label from the ASBR of the other autonomous system. Obtain the VPN in the original route to forward the route, and then forward the VPN message.

At this point, the message forwarding is completed. In the following, an embodiment is described in detail, how to establish and store the correspondence between the inbound label allocated to the aggregated route and the original route corresponding to the aggregated route, and use the corresponding relationship to correctly forward the packet. FIG. 5 is a flowchart of another method for implementing packet forwarding by using the route aggregation method of FIG. 3. Referring to FIG. 5, the method specifically includes the following steps:

Step 500: Create a Forward Information Base (FIB) table, also called an RD FIB table, for each RD routing table in the ASBR.

This step is performed once during ASBR configuration. After the RD FIB table is created, it is not necessary to perform the route aggregation every time.

The RD routing table is used to store the VPN-IPv4 routes received by the ASBR and the aggregated routes after the ASBR is aggregated. All VPN-IPv4 routes are stored in the corresponding RD routing table according to the RD. The fields in the RD routing table include RD, IPv4 address/mask, next hop node, RT, outgoing label, and so on.

Each RD FIB table corresponds to an RD routing table. It can also be said that each RD FIB table corresponds to a different RD. Since an aggregated route corresponds to multiple original routes, these original routes are called original routes suppressed by route aggregation. The RD FIB stores the original route that is suppressed by aggregation. The fields in the RD FIB table include RD, IPv4 address/mask, next hop node, RT, outgoing label, and so on.

Step 501: The ASBR receives the original route sent by multiple PEs, and performs aggregation processing on the same original route of the RD.

In this step, if the routes have been aggregated by the PEs, the original route received by the ASBR can be the route that is aggregated by the PE.

The ASBR will receive the original routes from multiple PEs, depending on the route specifier RD.

After receiving the original routes of multiple PEs, the ASBRs are respectively stored in the corresponding RD routing table according to the different routing specifiers RD, and the original routes received from the PEs in the RD routing tables respectively. The aggregation process is performed, and the aggregation route is stored in the corresponding RD routing table. The purpose of aggregating the original routes in each RD routing table is also to aggregate the same original routes of the RD. Aggregated routes are also VPN-IPv4 routes. After the aggregation process is performed in this step, the RD, IPv4 address prefix/mask, and RT of the aggregated route are determined.

RT is the information that is sent along with the route during the route advertisement process. The RT is divided into an entry RT (Import RT) and an exit RT (Export RT). The import RT list is configured in the VPN instance of the PE. When the exported RT of the route received by the PE matches the imported RT list in the PE, the route is imported into the VPN instance. RT acts as a route filter. The RT referred to in this embodiment refers to Export RT. During the route issuance, the RT attribute is attached to the route and sent simultaneously. Therefore, when the ASBR performs route aggregation, it also needs to process the RT. Generally, the same route of RD, its RT will be configured to be the same, but it may not be the same.

In the embodiment of the present invention, the RTs of the original routes participating in the aggregation may be the same, so that the aggregated routes use the same RT as the original routes. The RT of the original route participating in the aggregation can also be different. For the case where the original routes RT participating in the aggregation are different, the aggregation route can select the following strategies to determine the RT it carries:

1) taking the complete set of RTs carried by the original route participating in the aggregation;

2) taking the intersection of the RTs carried by the original routes participating in the aggregation;

3) Manually set the RT that the aggregated route can carry on the RD routing table.

4) Set the RT that the aggregated route can carry according to the routing policy.

Step 502: Add the original route suppressed by the route aggregation to the RD FIB table.

In an actual application, each original route that is suppressed by the route aggregation may be stored in the RD FIB table as a forwarding equivalence class map next hop mark forwarding entry (FTN, FEC to NHLFE). The fields of the FTN entry include the RD of the original route, the IPv4 address prefix/mask, the next hop node, the outgoing label, and the RT. Step 503: The ASBR allocates a label for the aggregated route, and creates an ILM of the incoming label. In this step, the operation of assigning the label to the aggregation route and creating the ILM of the inbound label can be performed in two ways. The first method is to assign an inbound label to each aggregation route, and then create an ILM for each inbound label. The second is to assign an ingress label to each RD routing table, and create an ILM for the ingress label corresponding to the RD routing table. The aggregated routes in the same RD routing table use the same ingress label. Essentially, assigning an ingress label to an RD routing table is to assign an ingress label to the same aggregated route of the RD. In the second mode, the label is allocated to the aggregation route, which saves the label resources of the ASBR. Here, the created type of ILM is pop-up (POP), and the mapping relationship is to map the inbound label to the corresponding RD FIB table. Therefore, the ILM includes the following fields:

In Tag Operation Type POP RD

Among them, the corresponding RD FIB table can be found through RD. Therefore, in this embodiment, the ILM records the correspondence between the ingress label allocated for the aggregated route and the RD FIB table corresponding to the RD of the aggregated route. The original route that is suppressed by aggregation is stored in the RD FIB table. Thus, it can be seen that the ILM and the RD FIB table jointly store the correspondence between the ingress label allocated for the aggregated route and the original route of the aggregated route.

If the original route received by the ASBR from the PE includes a route that cannot be aggregated, the route is processed according to the existing technology, that is, an ingress label is assigned to the route, and an operation type is exchanged (SWAP) for the ingress label. ILM. The ILM records the outgoing label corresponding to the incoming label. When the ASBR processes the received VPN packet, the corresponding ILM is found according to the ingress label at the top of the label stack. According to the SWAP operation indication in the ILM, the outgoing label in the ILM is exchanged with the incoming label at the top of the label stack, according to the ILM mapping. The next hop forwarding entry forwards the current MPLS text to the corresponding PE through the SP backbone network.

Step 504: The ASBR uses itself as the next hop node to advertise the aggregated route carrying the next hop node and the inbound label allocated for the aggregation route to the ASBRs of other autonomous systems. Step 505: After receiving the aggregated route, the ASBR of the other autonomous system re-assigns the next hop node and the ingress label, and then advertises the aggregated route to the PE in the autonomous system to which it belongs.

In this step, the subsequent operations performed by the ASBRs of other autonomous systems after receiving the aggregated routes are the same as those in the prior art. After the step is performed, the VPN-IPv4 routes on the PE and the ASBR are the same in the inter-AS VPN. The correct packet forwarding can be performed on the SP backbone network.

Step 506: When the ASBR of the local AS receives the packet carrying the label sent by the ASBR of the other autonomous system, searches for the corresponding ILM according to the inbound label carried in the packet, and obtains the corresponding RD FIB table according to the found ILM. The forwarded route of the 4 艮。。。。。。。。。。。。。。。。。

In this step, when the ASBR receives the VPN packet from the ASBR of the other autonomous system, the ASBR checks the inbound label of the top of the label of the VPN packet, finds the corresponding ILM according to the inbound label, and pops up according to the POP operation indication in the ILM. The inbound label of the label stack is obtained, and the IP packet is obtained. According to the RD indication in the ILM, the RD FIB table corresponding to the RD is found; and the destination address in the IP packet header is compared with the found RD FIB table. The IPv4 address prefix of the FTN item is matched by the longest match, and the outbound label of the matched FTN item is pushed into the label stack, and the packet is forwarded to the corresponding PE according to the next hop node through the SP backbone network.

The following describes the route aggregation in the embodiment of the present invention and the specific implementation process of routing advertisement and packet forwarding after route aggregation.

This example assumes that two VPN instances are configured on PE-1 in Figure 2: vpnl and vpn2. The routing information in the two VPN instances is the route learned from the CE connected to it.

The RD of vpnl is 100:1 and there are three routes: 10.1.1.0/24, 10.1.2.0/24, 10.1.3.0/24.

The RD of vpn2 is 100:2 and there are three routes: 20.1.1.0/24, 20.1.2.0/24, 20.1.3.0/24.

Configure two VPN instances on PE-2, vpnl and vpn2: The RD of vpnl is 100:1 and there are three routes: 10.2.1.0/24, 10.2.2.0/24, 10.2.3.0/24.

The RD of νρη2 is 100:2 and there are three routes: 20.2.1.0/24, 20.2.2.0/24, 20.2.3.0/24.

In the entire network, vpn1 on all PEs belong to the same VPN, and all vpn2 belong to another VPN. Both PE-1 and PE-2 can perform route summarization, and only the aggregated VPN-IPv4 routes are advertised to ASBR-1.

FIG. 6 is a flow chart showing an example of the message forwarding method of FIG. 5. Referring to Figure 6, the method includes the following steps:

In step 600, the ASBR creates two corresponding RD FIB tables for the routing tables with RDs of 100:1 and 100:2.

Step 601: PE-1 and PE-2 respectively aggregate and assign the routes configured in the VPN instance to the label, and use the self as the next hop node to generate an aggregated route of the PE.

In this step, PE-1 generates the aggregated route of PE-1 based on the two VPN instances.

RD 100:1 10.1.0.0/16 Next hop PE-1 Incoming label Lm RT 100:1; RD 100:2 20.1.0.0/16 Next hop PE-1 Incoming label Ln RT 100:2. PE-2 generates the aggregation route of PE-2 according to the two VPN instances configured as follows: RD 100:1 10.2.0.0/16 Next hop PE-2 Incoming label Lm RT 100:1; RD 100:2 20.2.0.0 /16 Next hop PE-2 Incoming label Ln RT 100:2. Step 602: PE-1 and PE-2 respectively send the aggregation route of the PE to ASBR-1.

In this step, the aggregation path of the PE-1 carrying the label from the PE-1 of the ASBR-1 is:

RD 100:1 10.1.0.0/16 Next hop PE-1 outgoing label Lm RT 100:1; RD 100:2 20.1.0.0/16 Next hop PE-1 outgoing label Ln RT 100:2. The aggregation route of the PE-2 carrying the label from the PE-2 of the ASBR-1 is:

RD 100:1 10.2.0.0/16 Next hop PE-2 outgoing label Lm RT 100:1;

RD 100:2 20.2.0.0/16 Next hop PE-2 outgoing label Ln RT 100:2. It should be noted that the outgoing label in the aggregated route of the PE received by the ASBR-1 is the incoming label of the aggregated route generated by the PE.

Step 603: The ASBR-1 aggregates the aggregated routes of the PEs received from PE-1 and PE-2 in the RD routing table corresponding to the RD. The routes that ASBR-1 receives from PE-1 and from PE-2 are called original routes.

In this example, ASBR-1 includes at least two RD routing tables, namely: an RD routing table with an RD of 100:1 and an RD routing table with an RD of 100:2. After polymerization, it is obtained:

The route 10.1.0.0/16 and 10.2.0.0/16 in the RD routing table with the RD of 100:1 generates the route 10.0.0.0/8, and the RT is 100:1. The aggregated route is saved to the RD with the RD of 100:1. In the routing table.

The route with the RD of 100:2 in the RD routing table is 20.0.1.0/16, 20.2.0.0/16, which generates 20.0.0.0/8, and the RT is 100:2. The aggregated route is saved to the RD route with the RD of 100:2. In the table.

Step 604: Add the original route suppressed by the route aggregation to the RD FIB table corresponding to each RD routing table.

In this step, an FTN entry is added to the RD FIB table with an RD of 100:1, and each FTN entry corresponds to a suppressed original route:

RD 100:1 10.1.0.0/16 Down--hop PE-1 Out Label Lm RT 100:1;

RD 100:1 10.2.0.0/16 Down--hop PE-2 Outbound Lm RT 100:1; Add FTN entry in the RD FIB table with RD 100:2:

RD 100:2 20.1.0.0/16 Down--hop PE-1 Out Label Ln RT 100:2;

RD 100:2 20.2.0.0/16 Next hop PE-2 out label Ln RT 100:2. Step 605: ASBR-1 assigns an inbound label to the RD routing table, and creates an ILM whose inbound label operation type is POP. Aggregated routes in the RD routing table use the ingress label assigned to the RD routing table to which they belong.

In this step, ASBR-1 assigns the label Lj to the RD routing table with the RD of 100:1; creates the ILM entry for Lj; assigns the label Lk to the RD routing table with the RD of 100:2; creates the ILM entry for Lk. The above two ILM items include:

Incoming label Lj operation type POP RD 100:1;

Incoming label Lk operation type POP RD 100:2.

It can be seen that the ASBR-1 of this example only needs to assign two labels to the route received from the PE to create two ILMs. In the prior art, the ASBR-1 assigns 4 ingress labels to the routes received from the PE to create 4 ILMs. It can be seen that the embodiment of the present invention not only reduces the number of routes sent by the ASBR, but also reduces the demand for labels.

Step 606: The ASBR-1 advertises the determined aggregation route to the ASBR-2 as the next hop node that advertises the route.

The aggregation route advertised by ASBR-1 to ASBR-2 is:

RD 100:1 10.0.0.0/8 Next hop ASBR-1 Incoming label Lj RT 100:1;

RD 100:2 20.0.0.0/8 Next hop ASBR-1 Incoming label Lk RT 100:2;

It can be seen that the ASBR-1 only needs to advertise the two VPN-IPv4 routes carrying the label to the ASBR-2. The current technology is used for the route advertisement. In the case that the VPN instances configured on PE-1 and PE-2 are the same, ASBR -1 A VPN-IPv4 route carrying the label is required to be advertised to the ASBR-2. Therefore, the route received and saved by the ASBR-2 is reduced to half of the original, and the route advertised by the ASBR-2 to the PE in the autonomous system is Also reduced to half of the original. Step 607: When the ASBR-1 receives the VPN packet carrying the label sent by the ASBR-2, searches for the corresponding ILM according to the inbound label carried in the packet, and finds the packet according to the ILM from the corresponding FIB table. Forward the route and forward the packet according to the forwarding route.

In this example, when the ASBR-1 receives the VPN packet from the ASBR-2 and assumes the label Lj at the top of the label stack of the VPN packet, the ASBR-1 finds the corresponding ILM according to the label Lj, according to the ILM. The RD is 100:1, and the RD FIB table with the RD of 100:1 is found. Then, according to the indication of the operation type POP in the ILM, the packet label is popped up to obtain an IP packet header; according to the destination address in the IP packet header. In the RD FIB table with the RD of 100:1, the longest matching method is used to match the original route, and the matching original route is used as the forwarding route of the VPN packet. Assuming that the destination address of the obtained IP packet is 10.1.1.2/32, the following original route is matched in the RD FIB table with the RD of 100:1:

RD 100:1 10.1.0.0/16 Next hop PE-1 outgoing label Lm RT100:1; B'J, according to the original route, put the new outgoing label Lm into the label stack of the VPN packet, and according to the next The PE-1 forwards the packet to the correct PE.

To implement the route aggregation method illustrated in Figure 3, the present invention provides an autonomous system border router. FIG. 7 is a schematic structural diagram of a first embodiment of an autonomous system border router according to the present invention. The autonomous system border router includes a route aggregation processing unit 701 and a label allocation unit 702.

The route aggregation processing unit 701 is configured to generate an aggregation route according to the original route received from multiple PEs. After the label is allocated to the aggregation route, the aggregation route carrying the inbound label is sent to the label allocation unit 702.

The label allocating unit 702 is configured to allocate an inbound label for each aggregated route received from the route aggregation processing unit 701, and generate an aggregated route carrying the incoming label.

In order to implement the packet forwarding method shown in FIG. 4, it is also required to add a related module for implementing packet forwarding in the composition of the foregoing ASBR. The specific embodiment is shown in FIG. 8.

FIG. 8 is a schematic structural diagram of a second embodiment of an autonomous system border router according to the present invention. Reference As shown in FIG. 8, the ASBR of this embodiment includes a route aggregation processing unit 801, a label distribution unit 802, a route issuing unit 803, a correspondence relationship recording unit 804, a storage unit 805, and a message forwarding unit 806.

The difference from the embodiment 1 of the autonomous system border router shown in FIG. 7 is that the ASBR in this embodiment further includes a correspondence relationship recording unit 804, a storage unit 805, and a message forwarding unit 806. among them,

The correspondence relationship recording unit 804 is configured to receive the aggregated route carried by the label distribution unit 804 and carry the inbound label, and obtain the original route corresponding to the aggregated route carrying the label from the route aggregation processing unit 801, and then assign the inbound label to the aggregated route. The correspondence between the original routes corresponding to the aggregated route is recorded in the storage unit 805.

The storage unit 805 is configured to store a correspondence between an inbound label allocated for the aggregated route and an original route corresponding to the aggregated route.

The text forwarding unit 806 is configured to receive the packet carrying the label sent by the ASBR of the other autonomous system, and find the original route corresponding to the label from the corresponding relationship in the storage unit 805 according to the ingress label carried in the packet. And obtain the forwarding route of the packet from the original route that is found, and forward the message.

In order to implement the message forwarding method shown in FIG. 5, the autonomous system border router configuration shown in FIG. 8 may be employed. The storage unit 805 stores the RD FIB table corresponding to each RD and the ILM table in which the ILM corresponding to each inbound label is stored. The storage unit 805 also stores an RD routing table corresponding to each RD. Each RD FIB table corresponds to an RD routing table.

The working principle of the other component units of the autonomous system border router embodiment 2 will be described below in comparison with the various tables stored in the storage unit 805.

The route aggregation processing unit 801 receives the original route of each PE, and aggregates the original routes of the same RD, and sends the aggregated route to the label distribution unit 802, and sends the aggregated route and its corresponding original route to the corresponding relationship record unit 804. . The label assigning unit 802 allocates an inbound label to each of the received aggregated routes, and sends the aggregated route that carries the incoming label to the corresponding relationship recording unit 804.

The correspondence relationship recording unit 804 receives the aggregated route sent by the route aggregation processing unit 801 and its corresponding original route, and also receives the aggregated route carried by the label allocation unit 802 and carries the incoming label. The original route corresponding to the aggregated route is stored in the corresponding RD FIB table in the storage unit 805 according to the RD; the ILM of the operation type POP is created for the inbound label carried in the aggregated route, and the ILM is stored in the ILM table of the storage unit 805. The aggregated route and its corresponding original route are stored in the corresponding RD routing table in the storage unit 805.

The text forwarding unit 806, when receiving the VPN text forwarded by the other ASBR, is configured to pop the inbound label according to the ILM indication to obtain an IP packet; and simultaneously find the corresponding RD in the storage unit 805 according to the RD in the ILM. RD FIB table; the destination address in the IP packet header is matched with the IPv4 address prefix of the FTN entry in the RD FIB table. The VPN packet is forwarded to the SP backbone network according to the matched FTN entry. Corresponding PE.

It can be seen from the above that the route aggregation method, the route forwarding based on the route aggregation, and the ASBR that can implement route aggregation and packet forwarding can effectively reduce the VPN issued by the autonomous system. - The number of IPv4 routes reduces the routing capacity of the ASBR and PE devices on the entire network. The label resources of the ASBR are saved, and a large number of ILM entries are avoided, which reduces the burden on the forwarding layer. Further, the number of VPN-IPv4 routes on the entire network and the ILM entries on the ASBR are reduced, thereby saving memory resources, reducing the refresh of forwarding information between the main control board and the interface board, and improving the operation of the network device. stability. When the route aggregation solution is applied to a large-scale cross-domain VPN network of the carrier, the problem that the routing capacity is insufficient and the label resources are insufficient on the ASBR can be effectively solved. Indirectly increases the routing capacity and stability of ASBR devices.

In conclusion, the above is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications, equivalents, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

A route aggregation method is applied to a network including at least one autonomous system border router (ASBR), and the ASBR is connected to at least one provider border device (PE), and the method includes:

The method according to claim 1, wherein before the ASBR receives the original route, the method further comprises: the PE aggregating the route to be sent, and sending the route to the ASBR;

The original route is a route after the PE is aggregated.

The method according to claim 1, wherein the assigning a label to each aggregated route is:

Assigning different labels to each aggregated route;

Or, assign the same label to the same aggregated route of the RD.

The method according to claim 1, wherein the original routes of the same RD and the same subnet are aggregated to generate an aggregated route: the ASBR prefixes/masks the RD and the IPv4 address according to the original route. The code combines multiple IPv4 address pre-/masks belonging to the same subnet into a short masked IPv4 address before the mask, and the merged IPv4 address prefix/mask is determined as the aggregated route of IPv4. The address prefix/mask determines the RD of the original route as the RD of the aggregated route, and determines the RT of the aggregated route according to the route target RT of the original route.

The method according to claim 4, wherein the determining the aggregated route RT is:

When the RTs of the original routes of the aggregated route are the same, the same RT is used as the RT of the aggregated route;

When the RTs of the original routes of the aggregation route are different, the complete set of RTs of the original routes is taken as the RT of the aggregated route, or the intersection of the RTs of the original routes is taken as the RT of the aggregated route, or the aggregated route is manually set. RT; or set the RT of the aggregated route according to the routing policy.

A text forwarding method is applied to a network including at least one ASBR, where the ASBR is connected to at least one PE, and the method includes:

The first ASBR receives at least one original route from the at least one PE, aggregates the original routes of the same RD, and generates an aggregated route, assigns a label to each aggregated route, and adds the label to the aggregated route. The label is generated, and an aggregated route carrying the label is generated.

The corresponding relationship between the label assigned to the aggregated route and the original route corresponding to the aggregated route; the aggregated route carrying the label is advertised to the second ASBR of another autonomous system;

The first ASBR receives the packet carrying the label from the second ASBR, and obtains a corresponding original route from the corresponding relationship according to the label carried in the packet; Obtaining the packet forwarding route; forwarding the packet according to the forwarding route.

The method according to claim 6, wherein the method further comprises: the first ASBR separately creating a corresponding forwarding information base (FIB) table for different RDs; the storing is a label allocated by the aggregated route and the The step of the corresponding relationship between the original routes corresponding to the aggregated route includes: recording the correspondence between the label and the RD that are allocated for the aggregated route; and recording the original route corresponding to the aggregated route in the FIB table corresponding to the RD of the aggregated route; The step of obtaining the forwarding route of the packet includes: searching for the corresponding RD from the corresponding relationship according to the label carried in the packet; and obtaining the original route from the FIB table corresponding to the found RD, Acquiring the forwarding route of the packet in the obtained original route; forwarding the packet according to the forwarding route.

The method according to claim 6 or 7, wherein the original route carries an IPv4 address prefix or a mask;

The obtaining the forwarding route of the packet includes: matching the destination IP address of the packet with the IPv4 address prefix carried in the obtained original route, and using the original route that is successfully matched as the packet Forward the route.

An autonomous system border router, which is applied to a network including multiple ASBRs, where each ASBR is connected to multiple PEs, and the ASBR includes a route aggregation processing unit and a label allocation unit.

The route aggregation processing unit is configured to receive multiple original routes from multiple PEs, and aggregate the original routes that belong to the same subnet, and generate an aggregation route, and send the aggregation route to the label distribution unit.

The autonomous system border router according to claim 9, wherein the autonomous system border router further comprises a route issuing unit, configured to send the label-carrying aggregation route to an ASBR of another autonomous system.

The autonomous system border router according to claim 10, wherein the autonomous system border router further comprises a storage unit, a correspondence relationship recording unit, and a message forwarding unit;

The correspondence relationship recording unit is configured to receive the carrying label of the label allocating unit And the original route corresponding to the aggregated route carrying the label is obtained from the route aggregation processing unit, and the label allocated for the aggregated route and the original route corresponding to the aggregated route are recorded in the storage unit. in;

The storage unit is configured to store a correspondence between a label allocated for an aggregated route and an original route corresponding to the aggregated route; and return, to the text forwarding unit, an original route corresponding to the label;

The packet forwarding unit is configured to receive a packet carrying a label sent by an ASBR of another autonomous system, and search for a corresponding original route from a correspondence stored in the storage unit according to the label carried in the packet. The forwarding route of the packet is obtained from the original route that is found, and the packet is forwarded according to the forwarding route.