WO2012079375A1 - Method and system for link protection in a virtual private network - Google Patents

Abstract

Disclosed in the present invention are a method and system for link protection in a virtual private network. Transmission nodes and reception nodes in the virtual private network are all connected with a main forwarding node and a standby transmitting node via pseudo wires, the method comprises the following steps: a standby channel is set for at least one of the pseudo wires(301); when the pseudo wire with a standby channel fails, services carried on the pseudo wire is switched to the standby channel(302). The technical solution provided by the present invention can be applied to the management of layer 2 link protection in a virtual private network.

Description

 Link protection method and system for virtual private network

 The present invention relates to a link protection technology for a virtual private network, and more particularly to a link protection method and system for a virtual private network.

Background technique

 MPLS TE (Multiprotocol Label Switching Traffic Engineering) Fast Reroute (FRR) is one of the most commonly used techniques for fast fault recovery. Its basic idea is to operate in two operations. An end-to-end traffic engineering (TE, Traffic Engineering) tunnel is established between the device (PE, Provider Edge), and a backup LSP is established in advance for the primary label switching path (LSP, Label Switched Path) to be protected. When the device detects that the primary LSP is unavailable (node failure or link failure), the device switches the traffic to the backup LSP to implement fast service switching.

 The MPLS TE FRR technology is a technology for implementing network local protection. In a network where MPLS TE is applied, when a link or node fails, the LSP configured with fast reroute protection can automatically switch data to the protection chain. Go on the road. MPLS TE FRR establishes a local backup path in advance, protecting the LSP from link/node failure. When a fault occurs, the device detecting the link/node failure can quickly switch the service from the faulty link to the backup path. At the same time, the head node of the LSP tries to find a new path to re-establish the LSP and switch the data to the new path. Before the new LSP is established successfully, the service data is always forwarded through the protection path.

 In addition, the virtual private network FRR (Virtual Private Network FRR) utilizes a VPN-based private network route fast handover technology, and sets the primary PE and the standby PE in the remote PE in advance. The primary and secondary forwarding entries, combined with the rapid detection of PE faults, are designed to solve the problem that the end-to-end service convergence time caused by PE node failure is longer in the MPLS VPN network where the user edge device (CE, Customer Edge) is dual-homed to the PE. The problem of s), and the problem that the PE node failure recovery time is related to the number of private network routes it carries. In the case of a PE node failure, the end-to-end service convergence time is less than ls.

Virtual Private Line Service (VPWS, Virtual Private Wire Service) is built on MPLS On top of the network infrastructure, high-speed Layer 2 transparent transmission is provided between a pair of ports on both routers.

 The main components of VPWS include: PE router, Label Distribution Protocol (LDP), and MPLS Label Switching Tunnel (LSP Tunnel). Interface devices that join the VPWS service support broadcast, forward, and filter Ethernet frames. The PEs are connected to each other by pseudowires (PW, Pseudo Wire) to form a simulated LAN for the client. Each PE not only learns the Media Access Control (MAC) address of the Ethernet packet from the PW, but also learns the MAC address from the CE it is connected to. The PW usually uses an MPLS tunnel to transparently transmit data between the PEs. The tunnel can be a Label Distribution Protocol (LDP), and the Resource ReSerVation Protocol-Traffic Engineering (RSVP-TE) Wait.

A PE is usually an MPLS edge router and can establish tunnels to other PEs.

 For a Layer 2 VPN network such as VPWS, how to protect the traffic when the link is disconnected is a problem that needs to be solved. Summary of the invention

 The present invention provides a link protection method and system for a virtual private network, which can shorten the time of service interruption when the link is interrupted, compared with the prior art.

 In order to solve the above technical problem, the present invention provides the following technical solutions:

 A link protection method for a virtual private network, where a sending node and a receiving node in the virtual private network are connected to an active forwarding node and a standby forwarding node by using a pseudowire to form the sending node and the primary forwarding node. And a path between the receiving node and the transmitting node, the standby forwarding node, and the receiving node, the method includes:

 Setting a standby tunnel for at least one of the pseudowires;

 When a pseudowire failure of the standby tunnel is set, the service carried by the failed pseudowire is switched to the standby tunnel.

The method further includes: if the path between the sending node, the primary forwarding node, and the receiving node is disconnected due to a fault, the sending node switches the path of the service to the sending node, and the standby forwarding A path between a node and the receiving node. Wherein: the path between the sending node, the primary forwarding node, and the receiving node, Forming a pseudowire or a backup tunnel between the transmitting node and the primary forwarding node, and a pseudowire or a standby tunnel between the primary forwarding node and the receiving node;

 a path between the sending node, the standby forwarding node, and the receiving node, a pseudowire or a standby tunnel between the sending node and the standby forwarding node, and the primary forwarding node and the A pseudowire or alternate tunnel consisting of receiving nodes.

 The step of switching the service carried by the failed pseudowire to the standby tunnel includes: if the backup tunnel does not pass through the routing node in the virtual private network, the forwarding label according to the pre-acquired standby tunnel will be faulty. The traffic carried by the pseudowire is switched to the standby tunnel.

 The step of switching the service carried by the failed pseudowire to the standby tunnel includes: if the standby tunnel passes through at least one routing node in the virtual private network, and performs service switching according to a pre-failed pseudowire To the alternate tunnel.

 A link protection system for a virtual private network, where a sending node and a receiving node in the virtual private network are connected to an active forwarding node and a standby forwarding node by using a pseudowire to form the sending node and the primary forwarding node. And a path between the receiving node and the transmitting node, the standby forwarding node, and the receiving node, the system includes a setting module and a first switching module, where:

 The setting module is configured to: set a standby tunnel for at least one pseudowire in the pseudowire; the first switching module is configured to: when a pseudowire fault of the standby tunnel is set, the faulty pseudowire is carried The service switches to the standby tunnel.

 The system also includes a second switching module,

 The second switching module is configured to: when the path between the sending node, the primary forwarding node, and the receiving node is disconnected due to a fault, switch the path of the service to the sending node, and the standby Transmitting a path between the node and the receiving node;

 The second switching module is deployed on the sending node.

Wherein: the path between the sending node, the primary forwarding node and the receiving node, and a pseudowire or a standby tunnel between the sending node and the primary forwarding node, and the primary forwarding a pseudowire or an alternate tunnel between the node and the receiving node; a path between the sending node, the standby forwarding node, and the receiving node, a pseudowire or a standby tunnel between the sending node and the standby forwarding node, and the primary forwarding node and the A pseudowire or alternate tunnel consisting of receiving nodes.

 The first switching module is configured to switch the service carried by the failed pseudowire to the standby tunnel in the following manner:

 When the standby tunnel does not pass through the routing node in the virtual private network, the service carried by the failed pseudowire is switched to the standby tunnel according to the forwarding label of the pre-acquired standby tunnel.

 The first switching module is configured to switch the service carried by the failed pseudowire to the standby tunnel in the following manner:

 When the standby tunnel passes through at least one routing node in the virtual private network, the service carried according to the pre-failed pseudowire switches to the standby tunnel.

The technical solution provided by the present invention, by setting a backup tunnel for a pseudowire, to switch to the standby tunnel when the pseudowire fails, and implementing local protection for the transmission link, and directly performing the active/standby forwarding node in the prior art. Compared with the handover, the service processing content required for the handover is reduced, thereby improving the switching speed, achieving the purpose of rapid handover, and shortening the time of service interruption. BRIEF abstract

 1 is a schematic structural diagram of an embodiment of a link protection system of a virtual private network according to an embodiment of the present invention;

 2 is a schematic diagram of networking of an embodiment of the present invention;

Preferred embodiment of the invention

The present invention will be further described in detail below with reference to the drawings and specific embodiments. It should be noted that, in the absence of conflict, The features in the embodiments and the examples in the application can be arbitrarily combined with each other.

 FIG. 1 is a schematic structural diagram of an embodiment of a link protection system of a virtual private network according to an embodiment of the present invention. The transmitting node and the receiving node in the virtual private network in the system embodiment shown in FIG. 1 are connected to the primary forwarding node and the standby forwarding node by using a pseudowire. The system includes: a setting module, a first switching module, and a second switching. Module, where:

 The setting module is configured to: set a standby tunnel for at least one of the pseudowires; the first switching module is configured to: when a pseudowire fault of the standby tunnel is set, switch the service carried by the failed pseudowire to the Said alternate tunnel.

 The setting module and the first switching module are deployed on a node, including at least one of a sending node, an active forwarding node, and an alternate forwarding node.

 The system further includes a second switching module, wherein the second switching module is configured to: switch the service path when the path between the sending node, the active forwarding node, and the receiving node is disconnected due to a fault And a path between the sending node, the standby forwarding node, and the receiving node. The second switching module is deployed on the sending node.

 a path between the sending node, the primary forwarding node, and the receiving node, a pseudowire or a standby tunnel between the sending node and the primary forwarding node, and the primary forwarding node a pseudowire or an alternate tunnel between the receiving nodes;

 a path between the sending node, the standby forwarding node, and the receiving node, a pseudowire or a standby tunnel between the sending node and the standby forwarding node, and the primary forwarding node and the A pseudowire or alternate tunnel consisting of receiving nodes.

The tunnel set for the pseudowire may be a tunnel directly connected between the nodes at both ends of the pseudowire, or may be formed by at least two tunnels between at least one routing node and nodes at both ends of the pseudowire, for example, sending The pseudowire between the node and the active forwarding node is provided with a standby tunnel, which may be a tunnel that directly connects the sending node and the primary forwarding node, or may be forwarded by the routing node A through the routing node A. The multi-segment tunnel connected by the node, that is, the tunnel between the sending node and the routing node A is M, and the tunnel between the routing node A and the active forwarding node is N, then the combination of the tunnel M and the tunnel N constitutes the transmitting node and the primary node. An alternate tunnel that forwards pseudowires between nodes. The first switching module is further configured to: when the standby tunnel does not pass through the routing node in the virtual private network, switch the service carried by the failed pseudowire to the standby tunnel according to the forwarding label of the standby tunnel.

 Since the standby tunnel does not pass through any routing node, the forwarding label of the standby tunnel includes information of the downstream node of the failed pseudowire, so the service can be routed to the downstream node of the failed pseudowire.

 The first switching module is further configured to: when the standby tunnel passes through at least one routing node in the virtual private network, a forwarding label according to the failed pseudowire and a forwarding label allocated by the routing node will occur The service carried by the failed pseudowire is switched to the standby tunnel.

 When the standby tunnel does not pass through any routing node, the forwarding label of the standby tunnel includes information of the downstream node of the failed pseudowire, so the service may be routed to the downstream node of the failed pseudowire; The standby tunnel passes through the routing node, and the routing node performs routing according to the forwarding label of the failed pseudowire, and routes the service to the downstream node of the failed pseudowire according to the forwarding label allocated by the next hop routing node.

 The system provided by the present invention provides a backup tunnel for a pseudowire, and when the pseudowire fails, the switch is switched to the standby tunnel to implement local protection on the transmission link, and the active/standby forwarding node is directly implemented in the prior art. Compared with the switching, the business processing content required for the switching is reduced, thereby improving the switching speed, achieving the purpose of rapid switching, and shortening the time of service interruption.

 The system provided by the present invention is further described in detail below:

 Before this, for the convenience of description, the relationship between the above links is simply named: the pseudowire and the alternate tunnel between the two ends of the pseudowire are called local protection of the link;

 The link between the sending node, the active forwarding node, and the receiving node is called the primary path. The link between the sending node, the standby forwarding node, and the receiving node is called the alternate path. These two paths are called the global link. protection.

In the data transmission process, the priority order of the path selection is a global protection primary path, a primary path, a local protection tunnel, a global protection alternate path, and an alternate path, a local protection tunnel. Here, the VPWS network is taken as an example for description, but is not limited thereto. For other MPLS-based protocols. The proposed Layer 2 virtual private network is also applicable, and will not be described here:

 In the networking process, in order to protect the link between the sending node and the receiving node, two forwarding nodes are configured, and the active/standby forwarding node is configured to be protected by the sending node and the receiving node respectively through the pseudowire; A tunnel is also arranged between the nodes at both ends of each pseudowire to implement switching between the pseudowire and the tunnel to achieve local protection of the primary path.

 In the above network structure, the link protection device creates a VPWS service forwarding, a global protection forwarding table, and a local protection forwarding table according to the structure of the network;

 The VPWS service forwarding table includes a global protection index, and is used to find a global protection table. See Table 1 in which the VC label in the VPWS table is the VC label of the primary label and the forwarding label.

 Table 1 VPWS forwarding table

 The global protection forwarding table records the primary path and the alternate path of the global protection, as shown in Table 2. Specifically, the forwarding label of the PW in the active path (that is, the pseudo-line forwarding label allocated by the primary forwarding node to the sending node) and the virtual circuit (VC) label (ie, the receiving node is allocated to the sending node to pass the primary use) Forwarding the virtual label of the node; the same as the forwarding label and VC label of the PW in the alternate path;

 The global protection forwarding table further includes a local protection flag bit and a local protection index, where: when the pseudo line of the main path fails, if the local protection flag is invalid, the data service packet is performed according to the global protection active/standby path. For protection switching, the forwarding label and VC label in the alternate path need to be used for transmission. When the local protection flag is valid, the data is forwarded according to the local protection table. At this time, the VC label is obtained from the global protection table, and the forwarding label is obtained from the local protection table. Obtained, the data service packet is protected and switched according to the locally protected tunnel.

Table 2 Global Protection Forwarding Table KEY Result

 VPNID Global Protection Index Local Protection Local Protection Primary PW VC Primary PW Transfer PW VC Standby PW Transfer Mark Index Label Label Label Label

The local protection forwarding table is generally used when a backup tunnel has multiple tunnels. See Table 3 for recording the active/standby relationship of the pseudowire and its corresponding tunnel in the local protection, the respective outbound port index, and the tunnel access. Tag information, where the egress port index is used to find the next bounce port table.

Local protection entry

 The following describes the contents of each item in the above table in combination with an application example.

 2 is a schematic diagram of the networking provided by the present invention, where PE1 and PE2 are source nodes and target nodes, respectively, where P1 is the primary node and P2 is the standby node, and PE1 and PE2 can communicate through PW1 and PW2, where PW1 includes PW11 and PW12, where PW11 (PE1-P1) and PW12 (P1-PE2), PW2 include PW21 (PE1-P2) and PW22 (P2-PE2). among them:

The MPLS TE protection tunnels of PW11 are Tl ( PE1-P3 ) and T2 ( P3-P1 ) ;

 The MPLS TE protection tunnels of the PW12 are T3 (P1-P4) and T4 (P4-PE2).

 Optionally, you can set the corresponding MPLS TE protection tunnel for PW21 and PW22 in advance, as shown in the following figure:

 The MPLS TE protection tunnels of the PW21 are T5 ( PE1-P5 ) and T6 ( P5-P2 ) ;

 The MPLS TE protection tunnels of the PW22 are T7 (P2-P6) and T8 (P2-PE2).

It can be seen that the starting point of the MPLS TE protection tunnel is the same as the starting point of each pseudo line. The PE1 device is used as an example. The VPWS forwarding table has a global protection index. The global protection table in the VPWS forwarding table is used to query the global protection table. The information about PW1 and PW2 can be obtained. The PW1 information includes the forwarding label assigned by P1 to PE1. PE2 is assigned to the VC label of PW1 of PE1; the information of PW2 includes the forwarding label assigned by P2 to PE1 and the VC label of PW2 allocated by PE2 to PE1. PW1 and PW2 both establish a protection relationship for local protection. Take PW11 as an example. A new tunnel consisting of tunnels T1 and T2 protects PW11. The local protection table is queried according to the local protection index in the global protection table. The pseudowire PW11 used and the tunnel T1 for standby.

 For Table 3, the PE1 device is used as an example. The local protection entry includes the primary tunnel forwarding label, the standby tunnel forwarding label, the next hop port information of the primary tunnel, and the next hop port information of the standby tunnel. The tunnel T1 and Τ2 protect the PW11 segment. The index of the local protection is Index1; the tunnels T3 and T4 protect the PW of the PW12, and the index of the local protection is Index2. The Index1 entry includes the primary tunnel forwarding label, which is the label that P1 assigns to PE1. The standby tunnel forwarding label is the label that P3 assigns to PE1. The next-hop outgoing port information of the primary tunnel is the outgoing port information of PE1 to P1. The port information is the outbound port information of PE1 to P3. The index 2 entry includes the label of the primary tunnel forwarding label that is assigned to P1 by PE2. The label of the standby tunnel is the label that P4 assigns to P1. The information of the next outbound port of the primary tunnel is P1. The outgoing port information of PE2, and the information of the next outgoing port of the standby tunnel is the outbound port information of P1 to P4.

 If there is no global protection, if there is no local protection, the forwarding label in the local protection table is the forwarding label assigned by P1 to PE1, and the next hop is directed to P1. At this time, the packet encapsulates the Layer 2 label for forwarding, and the outer forwarding label is localized. The protection table is obtained, the inner VC tag is obtained from the global protection table; if there is local protection switching, the forwarding label in the local protection table is the label assigned by P3 to PE1, and the inner label of the local protection protection is the label assigned by P1 to PE1. The time packet encapsulates the Layer 3 label for forwarding, and the outer layer 2 label is obtained from the local protection table, which is the label assigned by P3 to PE1, the inner label of the local protection protection is the label assigned by P1 to PE1, and the inner layer is the VC of PW1. The label is obtained from the global protection table, and the next hop is directed to P3 forwarding, thereby achieving local protection.

 The following describes the link switching mode:

 1) When both PW11 and PW12 are working normally, no link switching is required, and the path of communication between PE1 and PE2 is PW11-PW12;

2) When PW11 fails but PW12 is working normally, PE1 is faulty due to PW11 failure. The data is switched to the PW11 protection tunnel for transmission. After the P1 receives the data, the PW12 is still working, and the PW12 is still used for transmission. Therefore, the path of communication between PE1 and PE2 is T1-T2-PW12.

 3) When the PW11 is working normally but the PW12 is faulty, the PW11 is still working. The PW11 is still used for transmission. After the P1 receives the data, P1 switches the data to the PW11 protection tunnel for transmission. Because the PW12 fails, P1 will The data is switched to the protection tunnel of PW12 for transmission, so the path of communication between PE1 and PE2 is PW11-T3-T4;

 4) When both PW11 and PW12 are faulty, PE1 will switch data to the PW11 protection tunnel for transmission. After P1 receives the data, P1 will switch the data to the PW12 protection tunnel after the PW12 fails. Transmission, so the path of communication between PE1 and PE2 is T1 - T2 - T3 - T4;

 5) When at least one of the PW11 and the PW12 fails and the corresponding MPLS TE protection tunnel also fails, the standby node needs to be used for transmission, that is, the transmission between the PE and PE2 and the P2 is performed, so PE1 and PE2 The path of communication between them is PW21-PW22.

 Of course, if at least one of PW21 and PW22 is configured with an MPLS TE protection link,

When at least one of PW21 and PW22 fails, it can be handled by referring to 2 to 4 of the above cases.

 In the network shown in this application example, the method of transmitting data is as follows:

 Step 201: After determining that the received network packet is a VPWS network packet according to the access mode of the network packet, PE1 searches for a corresponding VPWS forwarding entry, where the VPWS forwarding table includes a global protection index, a PW VC label, and a forwarding. Label, ;

 Step 202: The PE1 searches for the global protection forwarding entry from the VPWS forwarding entry according to the global protection index that is found.

 Step 203, PE1 determines whether the local protection flag in the global protection forwarding is set, if yes, proceeds to step 204, otherwise proceeds to step 203;

 Step 204: The PE1 processes the received network packet in the manner that the global VPWS service global protection protection is configured, that is, the P1 network is transmitted from the PW11 to the P1, and the process ends.

Step 205: The PE1 searches for the partial protection according to the local protection index in the global protection forwarding table that is found. The guard entry, the local protection entry contains the next hop information to obtain the information of the TE primary tunnel and the standby tunnel (such as the outgoing port of the pseudowire and the outgoing port of the standby tunnel);

 Step 206: The PE1 encapsulates and forwards the VPWS service packet, which includes: obtaining the VC label of the VPWS service from the global protection table, the VC label is a label allocated by the LDP protocol, and the forwarding label of the VPWS service is a local protection entry. The label is obtained, and the label of the local protection entry is a label allocated by the RSVP protocol. The process ends.

 Similarly, after receiving the above content, P1 can refer to the processing flow of steps 201-206 to transfer data to PE2. If P1 cannot transmit data to PE2, P1 notifies PE1 that transmission cannot be performed, and PE1 passes between P2 and P2. The pseudowire transmits data to PE2.

FIG. 3 is a schematic structural diagram of an embodiment of a link protection method for a virtual private network according to the present invention. With reference to the systems shown in FIG. 1 and 2, the transmitting node and the receiving node in the virtual private network in the method embodiment shown in FIG. 3 are connected to the primary forwarding node and the standby forwarding node through a pseudowire to form the transmitting node. And a path between the primary forwarding node and the receiving node, and a path between the sending node, the standby forwarding node, and the receiving node, where the method includes:

 Step 301: Set a standby tunnel for at least one pseudowire in the pseudowire.

 Step 302: When a pseudowire fault with the standby tunnel is set, the service carried by the failed pseudowire is switched to the standby tunnel.

 The method further includes:

 And if the path between the sending node, the primary forwarding node, and the receiving node is disconnected due to a fault, the sending node switches the path of the service to the sending node, the standby forwarding node, and the receiving The path between nodes. The path in the method embodiment is specifically described as follows: the path between the sending node, the active forwarding node and the receiving node, and the pseudo between the sending node and the active forwarding node a line or backup tunnel, comprising a pseudowire or a standby tunnel between the primary forwarding node and the receiving node;

a path between the sending node, the standby forwarding node, and the receiving node, a pseudowire or a standby tunnel between the sending node and the standby forwarding node, and the primary forwarding node It consists of a pseudowire or an alternate tunnel between the receiving nodes.

 The step of switching the service carried by the failed pseudowire to the standby tunnel includes: if the backup tunnel does not pass through the routing node in the virtual private network, the forwarding label according to the pre-acquired standby tunnel will be faulty. The service carried by the pseudowire is switched to the standby tunnel; if the standby tunnel passes through at least one routing node in the virtual private network, the service carried according to the pre-failed pseudowire switches to the standby tunnel.

 The method of the present invention provides a backup tunnel for a pseudowire, and when the pseudowire fails, the switch is switched to the standby tunnel to implement local protection on the transmission link, and the active/standby forwarding node is directly implemented in the prior art. Compared with the switching, the business processing content required for the switching is reduced, thereby improving the switching speed, achieving the purpose of rapid switching, and shortening the time of service interruption.

It will be understood by those skilled in the art that all or part of the steps of the above embodiments may be implemented using a computer program flow, which may be stored in a computer readable storage medium, such as on a corresponding hardware platform (eg, The system, device, device, device, etc. are executed, and when executed, include one or a combination of the steps of the method embodiments.

 Optionally, all or part of the steps of the foregoing embodiments may also be implemented by using an integrated circuit. These steps may be separately fabricated into individual integrated circuit modules, or multiple modules or steps may be fabricated into a single integrated circuit module. achieve. Thus, the invention is not limited to any particular combination of hardware and software.

 The various devices/function modules/functional units in the above embodiments may be implemented using a general-purpose computing device, which may be centralized on a single computing device or distributed over a network of multiple computing devices.

 Each device/function module/functional unit in the above embodiments can be stored in a computer readable storage medium when implemented in the form of a software function module and sold or used as a standalone product. The above mentioned computer readable storage medium may be a read only memory, a magnetic disk or an optical disk or the like.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and any person skilled in the art can easily within the technical scope disclosed by the present invention. Any changes or substitutions are contemplated as being within the scope of the invention. Therefore, the scope of the invention should be determined by the scope of the claims.

Industrial applicability

 The technical solution provided by the present invention, by setting a backup tunnel for a pseudowire, to switch to the standby tunnel when the pseudowire fails, and implementing local protection for the transmission link, and directly performing the active/standby forwarding node in the prior art. Compared with the switching, the business processing content required for the switching is reduced, thereby improving the switching speed, achieving the purpose of rapid switching, shortening the time of service interruption, and having strong industrial applicability.

Claims

Claim A link protection method for a virtual private network, where a sending node and a receiving node in the virtual private network are connected to an active forwarding node and a standby forwarding node by using a pseudowire to form the sending node and the primary node. a path between the forwarding node and the receiving node, and a path between the sending node, the standby forwarding node, and the receiving node, where the method includes:  Setting a standby tunnel for at least one of the pseudowires;  When a pseudowire failure of the standby tunnel is set, the service carried by the failed pseudowire is switched to the standby tunnel. 2. The link protection method according to claim 1, further comprising:  And if the path between the sending node, the primary forwarding node, and the receiving node is disconnected due to a fault, the sending node switches the path of the service to the sending node, the standby forwarding node, and the receiving The path between nodes. 3. The link protection method according to claim 2, wherein:  a path between the sending node, the primary forwarding node, and the receiving node, a pseudowire or a standby tunnel between the sending node and the primary forwarding node, and the primary forwarding node a pseudowire or an alternate tunnel between the receiving nodes;  a path between the sending node, the standby forwarding node, and the receiving node, a pseudowire or a standby tunnel between the sending node and the standby forwarding node, and the primary forwarding node and the A pseudowire or alternate tunnel consisting of receiving nodes. The link protection method according to any one of claims 1 to 3, wherein the step of switching the service carried by the failed pseudowire to the standby tunnel comprises:  If the standby tunnel does not pass through the routing node in the virtual private network, the service carried by the failed pseudowire is switched to the standby tunnel according to the forwarding label of the pre-acquired standby tunnel. The link protection method according to any one of claims 1 to 3, wherein the step of switching the service carried by the failed pseudowire to the standby tunnel comprises: If the standby tunnel passes through at least one routing node in the virtual private network, according to the pre- The service carried by the failed pseudowire switches to the standby tunnel. A link protection system for a virtual private network, wherein the sending node and the receiving node in the virtual private network are connected to the primary forwarding node and the standby forwarding node by using a pseudowire to form the sending node and the primary node. a path between the forwarding node and the receiving node and a path between the sending node, the standby forwarding node, and the receiving node, the system comprising a setting module and a first switching module, where:  The setting module is configured to: set a standby tunnel for at least one pseudowire in the pseudowire; the first switching module is configured to: when a pseudowire fault of the standby tunnel is set, the faulty pseudowire is carried The service switches to the standby tunnel. 7. The link protection system according to claim 6, further comprising a second switching module, wherein the second switching module is configured to: at the transmitting node, the primary forwarding node, and the receiving node When the path between the two is disconnected due to a fault, the path of the service is switched to the path between the sending node, the standby forwarding node, and the receiving node;  The second switching module is deployed on the sending node. 8. The link protection system according to claim 7, wherein:  a path between the sending node, the primary forwarding node, and the receiving node, a pseudowire or a standby tunnel between the sending node and the primary forwarding node, and the primary forwarding node a pseudowire or an alternate tunnel between the receiving nodes;  a path between the sending node, the standby forwarding node, and the receiving node, a pseudowire or a standby tunnel between the sending node and the standby forwarding node, and the primary forwarding node and the A pseudowire or alternate tunnel consisting of receiving nodes. The link protection system according to any one of claims 6 to 8, wherein: the first switching module is configured to switch the service carried by the failed pseudowire to the standby tunnel in the following manner: When the standby tunnel does not pass through the routing node in the virtual private network, according to the pre-acquisition The forwarding label of the standby tunnel switches the service carried by the failed pseudowire to the standby tunnel. 10. The link protection system according to any one of claims 6 to 8, wherein: the first switching module is configured to switch the service carried by the failed pseudowire to the standby tunnel in the following manner: When the standby tunnel passes through at least one routing node in the virtual private network, the service carried according to the pre-failed pseudowire switches to the standby tunnel.