WO2011147299A1

WO2011147299A1 - Fast reroute method and apparatus in layer-2 virtual private network

Info

Publication number: WO2011147299A1
Application number: PCT/CN2011/074534
Authority: WO
Inventors: 李宁; 王韶夏
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-05-25
Filing date: 2011-05-23
Publication date: 2011-12-01
Also published as: CN101860482B; CN101860482A

Abstract

The present invention discloses a Fast ReRoute (FRR) method in a layer-2 virtual private network, which includes: respectively establishing a main and a standby FRR table for a pre-established main link and standby link, and adding the FRR index information of the established main FRR table and standby FRR table to a Media Access Control (MAC) address forwarding table; searching for the corresponding FRR table according to the FRR index information in the MAC address forwarding table, and performing inner layer label switching and/or outer layer label switching according to the label switching type marked by the mark bit in the standby FRR table. The present invention also discloses a fast reroute apparatus in a layer-2 virtual private network. A switching module in the apparatus is used for performing FRR switching to the standby link when it is detected that the main link is down. During the FRR switching due to a link failure in a Virtual Private Local area network Service (VPLS), the present invention considers not only inner layer label switching, but also outer layer label switching, thus ensuring the seamless transmission of the traffic, and improving the network stability.

Description

Layer 2 virtual private network fast rerouting method and device

The present invention relates to the field of communications, and in particular, to a Layer 2 virtual private network fast rerouting method and apparatus. Background technique

Today, with the rapid development of the network, the demand for triple play is becoming more and more urgent. Operators attach great importance to the service convergence speed when the network is faulty. When any node or link fails, the adjacent node services are quickly switched, end-to-end. The rapid convergence of services has gradually become a rigid requirement for bearer networks.

Various fast convergence techniques should be developed for the requirements of the bearer network for stable forwarding of devices. However, they are not well solved in the user-edge router device (CE, Custom Edge) dual-homing service provider edge router device (PE, Provider). In the network of Edge), the end-to-end service quickly converges when the link fails. Virtual Private Network (VPN) Fast Reroute (FRR) is dedicated to solving the end-to-end service convergence problem of the most common network model such as CE dual-homing, and will end-to-end services in the event of a failure. The convergence time is controlled within Is.

The CE dual-homing network is a very common form of networking in a real-world network. The VPN FRR technology is based on this network model and is deployed on the remote PE. The VPLS matching policy can be used to select the remote CE route to be protected. To solve the problem of fast end-to-end service convergence when the primary PE fails.

Multi-protocol label switching Layer 2 virtual private network MPLS L2VPN is the transparent transmission of user's Layer 2 data on the MPLS network. From the user's point of view, this MPLS network is a Layer 2 switching network through which Layer 2 connections can be established between different sites. MPLS L2VPN includes two types of virtual leased lines (VLL, Virtual Leased Line) and VPLS. VPLS is a widely used Layer 2 VPN technology.

The fault detection of existing links and nodes is mainly applied to the public network or private network. For the universally applied Multi-Protocol Label Switching (MPLS) network, the switching of the private network is likely to cause the forwarding path to the public network. The change, however, does not present an effective solution to the prior art for this situation.

In summary, it can be seen that in the prior art, the switching of the private network during the VPN FRR handover may cause the transition of the public network forwarding path to reduce the stability of the network. Therefore, it is necessary to propose an improved technical means. , to solve this problem. Summary of the invention

The present invention has been made in view of the prior art that there is a problem that the switching of the private network during the VPN FRR handover may cause the transition of the public network forwarding path to reduce the stability of the network, and the main purpose of the present invention is to provide a A Layer 2 virtual private network fast rerouting method and device, wherein: the Layer 2 virtual private network fast rerouting method according to the embodiment of the present invention includes: creating primary and backup fast rerouting for the pre-established primary link and backup link respectively (FRR) table, and add the FRR index information of the created primary and backup FRR tables to the media access control MAC address forwarding table; if it detects that the primary link is unavailable, perform FRR handover to the standby link; according to the MAC address The published FRR index information finds the corresponding FRR table, and performs inner label switching and/or outer label switching according to the label switching type marked by the label bit in the standby FRR table.

Preferably, after the FRR table is created for the pre-established primary link and the standby link, the method further includes: limiting the MAC address learning capability of the standby link.

Preferably, the corresponding FRR table is searched according to the FRR index information in the MAC address forwarding table, and the inner label switching and/or the outer label switching are performed, and the method further includes: reading the FRR index information according to the MAC address forwarding table. The FRR table is used to determine the label switching type according to the flag bit in the standby FRR table: If the inner label is switched, the inner label value is obtained according to the standby FRR table. Perform the inner label switching; determine whether the outer label switching is required. If necessary, obtain the outer label value according to the standby FRR table and perform outer label switching; if the outer label is switched, obtain the outer layer according to the standby FRR table. The tag value directly switches the outer tag.

Preferably, after the label switching is completed, the method further comprises: quickly forwarding the MAC address entry learned from the primary link by the MAC address forwarding table, and performing network-wide update.

Preferably, after the label switching is completed, the method further includes: removing the limitation of the MAC address learning capability of the standby link.

Preferably, before the FRR table is created for the pre-established primary link and the standby link, the method further includes: configuring at least one standby link for the primary link.

The Layer 2 virtual private network fast rerouting device according to the embodiment of the present invention includes: a table management module, configured to respectively create a primary and backup fast reroute (FRR) table for the pre-established primary link and backup link, and create The FRR index information of the primary and backup FRR tables is added to the media access control MAC address forwarding table; the switching module is configured to perform FRR handover to the standby link when the primary link is unavailable, and the label switching module is configured to The FRR index information in the address forwarding table finds the corresponding FRR table, and performs inner label switching and/or outer label switching according to the label switching type marked by the label bit in the standby FRR table.

Preferably, the label switching module further includes: a determining module, configured to read the standby FRR table according to the FRR index information in the MAC table, and determine whether to perform inner label switching or outer label switching according to the marking bit in the standby FRR table: a switching module, configured to: if the inner label is switched, obtain an inner label value according to the standby FRR table and perform inner label switching; and then determine whether an external switch is needed; and the second switching module is configured to switch if the outer label is Then, the outer label is directly switched according to the FRR table to obtain the outer label value.

Preferably, the apparatus further includes: an address update module, configured to quickly revoke the MAC address entry learned from the primary link, and perform network-wide update. Preferably, the device further includes: a configuration module, configured to configure at least one standby link for the primary link.

Compared with the prior art, according to the technical solution of the present invention, when the VPLS network link fails to perform FFR switching, not only the inner label switching but also the outer label switching is considered, the seamless transmission of the traffic is ensured, and the network stability is improved. Sex. DRAWINGS

1 is a schematic diagram of a network topology of a Layer 2 VPN FRR usage scenario according to Embodiment 1 of the present invention;

2 is a flow chart of a method for fast rerouting of a layer 2 virtual private network according to Embodiment 2 of the present invention;

3 is a flow chart of a method for fast rerouting of a layer 2 virtual private network according to Embodiment 3 of the present invention;

4 is a block diagram of a Layer 2 virtual private network fast rerouting apparatus according to Embodiment 4 of the present invention. detailed description

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

According to an embodiment of the present invention, a Layer 2 virtual private network fast rerouting method is provided. 1 is a schematic diagram of a network topology of a Layer 2 VPN FRR usage scenario according to Embodiment 1 of the present invention. As shown in FIG. 1, a primary link (primary PW) is established between UPE1 and NPE1, and a relationship is established between UPE1 and NPE2. The backup link (standby PW) implements the forwarding path protection for the primary link of the VPLS. The service provider edge routers (NPE and UPE) and the user edge router (CE) shown in FIG. 1 are merely illustrative, but the invention is not limited thereto.

2 is a flow chart of a method for fast rerouting of a two-layer virtual private network according to Embodiment 2 of the present invention; As shown in FIG. 2, the method includes (steps S202-S206):

Step S202: Create an FRR table for the pre-established primary link and the standby link, and add the FRR index information of the created FRR table to the media access control MAC address forwarding table.

The FRR table of the primary link is called the primary FRR table. The FRR table of the standby link is called the standby FRR table. After the FRR table is created, you need to limit the MAC address learning capability of the standby link to prevent MAC address flooding.

Step S204: If it is detected that the primary link is unavailable, perform FRR handover to the standby link. The primary link can be detected by using multiple detection methods. For example, BFD (Bidirectional Forwarding Detection) is used for detection. When the primary link is unavailable (DOWN), the FRR is switched to the primary link. Backup link.

Step S206: Find the corresponding FRR table according to the FRR index information in the MAC address forwarding table, and perform inner label switching and/or outer label switching.

Specifically, when the primary link is switched to the backup link, the FRR table is read according to the FRR index information in the MAC address forwarding table, and the label switching type is determined according to the flag bit in the standby FRR table: if the inner label is switched, according to The FRR table obtains the inner label value and performs the inner label switching. Then, it is determined whether the outer label switching is required. If necessary, the outer label value is obtained according to the standby FRR table and the outer label is switched.

If the outer label is switched, the outer label value is directly obtained according to the FRR table. It is not necessary to determine whether the inner label switching is required. Update and remove the MAC address learning capability limit of the standby link and relearn the MAC to complete the primary and backup link switching.

Through the above processing, when the VPLS network link fails to perform FFR switching, not only the inner label switching but also the outer label switching is considered, the seamless transmission of the traffic is ensured, and the network stability is improved. Details of each of the above processes will be described in detail below with reference to FIG.

3 is a flowchart of a VPLS fast rerouting method according to Embodiment 3 of the present invention, and FIG. 3 includes:

Step S302: Establish a primary and backup Spoke-PW link, and configure a Layer 2 VPN FRR service to protect the primary PW forwarding path of the VPLS.

Step S304: Create a primary and backup FRR table, and add index information of the primary and secondary FRR tables in the MAC address forwarding table.

The multi-protocol border gateway protocol (MBGP, Multiprotocol BGP) can be used to calculate the alternate link that can be used, and the corresponding information is added to the MAC address table and the FRR table. After the primary link is Down, the packet is forwarded. When the MAC table is read, as long as the FRR switch can be performed, the corresponding FRR table is read according to the routing information.

Step S306, limiting the MAC learning capability of the standby PW. The MAC learning of the standby PW is mainly used to prevent MAC flooding. When the primary link is UP (normal), the standby link is not used.

Step S308: The PW-BFD is used to detect the primary PW. When a fault is detected on the link, the FRR is switched.

Step S310: Check the corresponding flag bit in the MAC address table, read the index of the FRR table, and find the FRR table.

Specifically, the FRR table is read according to the FRR index information in the MAC table, and the flag bit in the FRR table indicates whether the inner VPN FRR switch or the outer VPN FRR switch is performed at this time.

If the inner label is switched, replace the label with the inner label in the original message. The change of the private network label causes the forwarding path to be different. The path of the public network packet may be different, which may cause the outer label to change. Therefore, you need to determine whether the outer VPN FRR switch needs to be performed.

The Interior Gateway Protocol (IGP) and the Label Distribution Protocol (LDP) can calculate the changes of the public network route and are reflected in the MAC address. In the address table, according to the index information of the FRR table in the MAC address table, the flag bit in the table indicates whether the outer label switching needs to be performed at this time. If yes, the outer label in the original packet is replaced by the outer label in the original packet. The change of the public network path.

If the FRR table is read according to the FRR index information in the MAC address table, the flag bit in the table indicates that the outer label switch is performed at this time, and it is not necessary to determine whether to perform inner label switching.

Step S312: Perform a Mac Withdraw operation to update the MAC of the entire network while the FRR is switched. MAC Address Withdrawal is applied to the PE device to quickly undo the MAC address entry learned from the PW, and then perform MAC update. This feature has been implemented and will not be described here.

In step S314, the MAC learning restriction on the standby PW is removed, so that the MAC is learned again. Step S316: After the MAC address of the entire network is updated, and the standby PW learns the MAC, complete the FRR active/standby switchover to restore traffic and services.

It should be noted that, after switching to the standby link, once the primary link is restored, the routing protocol automatically converges, then the FRR will switch back to the primary link; if the primary link is not restored, the backup link is DOWN again. In this case, the routing protocol will again calculate the convergence of the third link to meet the FRR handover requirements. Depending on the performance of the device, you can configure the FRR switchover link to meet the requirements of the high-reliability networking environment to reduce the fast switching between the two links and reduce the time it takes for the routing protocol to converge.

Device embodiment

According to an embodiment of the present invention, a Layer 2 virtual private network fast rerouting device is also provided.

4 is a two-layer virtual private network fast rerouting device according to an embodiment of the present invention. As shown in FIG. 4, the device includes: a table management module 10, a switching module 20, and a label switching module 30, where: a table management module 10, The FRR table is created for the pre-established primary link and the standby link, respectively, and the FRR index information of the created FRR table is added to the MAC address forwarding table; The switching module 20 is configured to detect that the primary link is unavailable, and perform FRR switching to

The label switching module 30 is configured to find a corresponding FRR table according to the FRR index information in the MAC address forwarding table, and perform inner label switching and/or outer label switching.

The label switching module 30 further includes: a determining module, configured to read the FRR table according to the FRR index information in the MAC table, and determine whether to perform inner label switching or outer label switching according to the marking bit in the FRR table:

The first switching module is configured to: if the inner label is switched, obtain the inner label value according to the standby FRR table and perform inner label switching; and then determine whether the outer label switching is required, and if necessary, if the outer label is switched Then, the outer label is directly switched according to the FRR table to obtain the outer label value, and it is not necessary to determine whether the inner label switching is required.

Moreover, the Layer 2 virtual private network fast rerouting device according to the embodiment of the present invention further includes: an address update module 40, configured to quickly cancel the MAC address entry learned from the primary link, and perform network-wide update; Used to configure at least one standby link for the primary link.

In the actual application, the specific processing procedure of the virtual private network fast rerouting device according to the embodiment of the present invention may be referred to FIG. 1 to FIG. 3 , and details are not described herein.

In summary, according to the above technical solution of the present invention, when the VPLS network link fails to perform FFR switching, not only the inner label switching but also the outer label switching is considered, the seamless transmission of the traffic is ensured, and the network stability is improved.

The above is only the embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. All modifications, equivalents, improvements, etc., made within the spirit and scope of the invention are intended to be included within the scope of the appended claims.

Claims

Claim

A method for fast rerouting of a Layer 2 virtual private network, the method comprising: creating a primary and backup fast reroute (FRR) table for a pre-established primary link and a backup link, respectively, and creating the Adding FRR index information of the primary and backup FRR tables to a media access control (MAC) address forwarding table;

If it is detected that the primary link is unavailable, performing FRR handover to the standby link; searching for a corresponding FRR table according to the FRR index information in the MAC address forwarding table, and according to the FRR table in the standby FRR table The tag switch type of the tag bit tag, for inner tag switching and/or outer tag switching.

The method according to claim 1, wherein after the FRR table is created for the pre-established primary link and the standby link, the method further includes:

Limiting the MAC address learning capability of the standby link.

The method according to claim 2, wherein the searching for the corresponding FRR table according to the FRR index information in the MAC address forwarding table, and performing inner label switching and/or outer label switching, Further includes:

And reading the FRR table according to the FRR index information in the MAC address forwarding table; determining the label switching type according to the flag bit in the standby FRR table;

If the inner label is switched, the inner label value is obtained according to the standby FRR table, and the inner label is switched; and then the outer label switching is required. If necessary, the outer label value is obtained according to the standby FRR table. Outer label switching;

If the outer label is switched, the outer label is directly switched according to the outer FRR table.

The method according to claim 3, wherein after the label switching is completed, the method further includes:

Fast 4 credits the MAC address forwarding table to learn the MAC address bar from the primary link And make a network update.

The limitation on the MAC address learning capability of the standby link is removed.

The method according to claim 1, wherein before the FRR table is created for the pre-established primary link and the standby link, the method further includes:

Configuring at least one standby link for the primary link.

A two-layer virtual private network fast rerouting device, the device comprising: a table management module, configured to respectively create a primary and backup fast reroute (FRR) for a pre-established primary link and backup link. a table, and adding the created FRR index information of the primary and secondary FRR tables to the media access control MAC address forwarding table;

a switching module, configured to detect that the primary link is unavailable, and perform FRR switching to the standby link;

a label switching module, configured to search for a corresponding FRR table according to the FRR index information in the MAC address forwarding table, and perform inner label switching and/or according to a label switching type marked by a label bit in the standby FRR table. The outer label is switched.

8. The apparatus according to claim 7, wherein the label switching module further comprises:

a judging module, configured to read the FRR table according to the FRR index information in the MAC table, and determine, according to the flag bit in the FRR table, whether to perform inner label switching or outer label switching;

a first switching module, configured to: if the inner label is switched, obtain an inner label value according to the standby FRR table and perform inner label switching; and then determine whether an outer label switching is required, and if necessary, the second switching module, If the outer label is switched, the method is obtained according to the standby FRR table. The outer label value directly switches the outer label.

The device according to claim 7, wherein the device further comprises: an address update module, configured to quickly cancel the MAC address entry learned from the primary link, and perform network-wide update.

The device according to claim 7, wherein the device further comprises: a configuration module, configured to configure at least one standby link for the primary link.