CN1394053A - Fast protecting switching method for multi-protocol label exchange - Google Patents

Abstract

A multi-protocol label switching fast protection switching method, which includes: establishing a protection link with the same start point and end point as the protected link, establishing a protection label switching path along the protection link; The protection link performs fault detection; when a fault is detected, the data is marked with a label switching path and returned to the port that sent the data, and the port that sends the data forwards the data to the router where the faulty port is located through the protection link, and then passes Top-level label switching forwards data to the failed port. It occupies very little system capacity and is not limited to specific physical layer applications.

Description

Multiprotocol Label Switching Fast Protection Switching Method

The invention relates to network protection of data communication, in particular to a multi-protocol label switching fast protection switching method.

In data communication, a basic requirement of IP network is stability and reliability, which requires network equipment to provide a certain protection function, to have fault recovery capability when a local fault occurs in the network, and to ensure that the user's business is not interrupted as much as possible flow. The traditional protection technology can be divided into three categories according to the protocol level: the physical layer, the link layer and the IP (network) layer. Chinese patent application CN1230065A discloses a method for realizing fast protection switching, as shown in FIG. 1 . In Figure 1, each SDH network element A, B, C, and D automatically generates cross-connection matrix control data under normal operation and various protection modes according to their business upper and lower relationships and the protection mode of the loop, and stores them in each network element In the cross-connect matrix control storage area reserved in the network, when various faults occur in the loop, the following steps are performed: each SDH network element determines its position relative to the fault point; the main control unit in each SDH network element according to its A switching command is issued relative to the location of the fault point; each network element executes the switching command, and replaces the control data of the cross-connect matrix under normal operation with the control data of the cross-connect matrix under the corresponding protection mode. The disadvantage of this method is that in the cross-connect matrix control storage area, all the cross-connect matrix control data under normal operation and various protection modes should be stored. No matter which protection mode the cross-connect matrix control data is not saved, it will cause When this fault occurs, effective protection cannot be performed, so it has the disadvantage of occupying a large system capacity. In addition, this method can only be applied on a specific physical layer. Once the topology of the network changes, it is necessary to regenerate new cross-connect matrix control data.

The purpose of the present invention is to provide a multi-protocol label switching fast protection switching method, which does not need to store a large number of connection protection data under various fault conditions and various protection modes, occupies a very small system capacity, and is not limited to specific Applied on the physical layer, even if the topology of the network changes, it can still effectively implement protection.

To achieve the above object, the solution of the present invention is: a multi-protocol label switching fast protection switching method, which includes

a. Establish a protection link with the same starting point and end point as the protected link, and establish a protection label switching path along the protection link;

b. The port of the protected link performs fault detection on the protected link;

c. When a fault is detected in step b, the data sent to the faulty port will be marked with a label switching path and returned to the port that sent the data, and the port that sent the data will forward the data to the port where the faulty port is located through the protection link The router then forwards the data to that failed port via top-level label switching.

In step a, protection label switching paths are respectively established along the forward and reverse directions of the protection link.

In step b, fault detection can be carried out in such a way: the physical layer chip of the port of the protected link detects the port speed by itself, and compares the speed with the set standard value, once the speed is lower than The set standard value sends an alarm signal to the central processing unit controlling the port, so as to detect the fault of the protected link.

In step b, fault detection can also be performed in this way: the protected link is connected with the PPP link layer protocol, and the port sending the data sends an Echo-Request to the port receiving the data at a certain time interval message, the port receiving the data sends an Echo-Reply message back to the port sending the data after receiving the Echo-Request message, and the port sending the data judges the protected link by detecting whether the Echo-Reply message is received If a fault occurs, it is determined that the protected link is not faulty if the message is received, and it is determined that the protected link is faulty if the message is not received.

In step a, before the protection label switching path is established, the protection label is configured for the established protection label switching path, and the protection label contains which port of the router that sends the data is transferred to which protection label switching path via which other router Information about which port on the router that received the data arrived. In step c, after the data sent to the faulty port is marked with a label switching path and returned to the port that sent the data, the central processor of the port that sent the data identifies the information carried by the protection label, and according to the protection The information carried by the label sends the data to the router at the faulty port through the label switching path, and the router at the faulty port exchanges the top-level label, releases the target port information of the protection label, and exchanges it with the information of the faulty port.

Since the multi-protocol label switching fast protection switching method of the present invention is aimed at links, it establishes a protection link for each protected link. Once a fault is detected on the protected link, the data is immediately added to the label switching path Marking, through the protection link forwarding to the router where the faulty port is located, and forwarding the data to the faulty port through top-level label switching, this detection does not depend on the topology of the network and the fault status of other links, so it does not need to store A large number of connection protection data under various fault conditions and various protection methods occupies a very small system capacity, and because it does not depend on the topology of the network, it is not limited to specific physical layer applications, even if the network Even if the topology changes, the protection can still be implemented effectively.

Fig. 1 is a schematic diagram of implementing network protection switching in the prior art.

Fig. 2 is a flow chart of the multi-protocol label switching fast protection switching method of the present invention.

Fig. 3 is a schematic diagram of MPLS fast protection switching according to the present invention.

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 2 is a flow chart of the multi-protocol label switching fast protection switching method of the present invention, and it can be seen from Fig. 2 that the implementation steps of the present invention are as follows.

(1) Establish a protection link with the same start point and end point as the protected link, and establish a protection label switching path along the protection link.

The present invention establishes a protection link for each specific link that needs to be protected. The protection link itself may not be new, but existed before. It is just for transmitting data between other routers. For example, the C3 port in Figure 3 reaches the C4 port via L2 via other routers and then via L3. After the protected link is set, the data transmitted normally and the data switched to this link after the protected link fails are transmitted at the same time.

Each protection label switching path corresponds to a protection label. This protection label is configured before establishing a protection label switched path. The protection label contains information on which port of the router sending the data is transferred to which port of the router receiving the data via which other router to which protection label switched path is relayed.

The method of configuring the protection label for the established protection label switching path is to configure a register, and the central processing unit of the failed port writes to the register which protection line is relayed from which port of the router sending the data via which other router. Information about which port of the router that the label switching path reaches to receive the data is switched to the protection link according to the path of this information during channel switching described later.

Since the protection label switching trail is unidirectional, it is necessary to configure protection label switching trails in both directions. Each protected link needs to be configured with two protection label switching paths.

In order to make the establishment of the protection label switching path extend the protection path and configure the protection strategy parameters such as bandwidth and quality of service registration, the establishment of the protection label switching path needs to use CR-LDP signaling.

(2) The port of the protected link performs fault detection on the protected link.

There are basically two options for fault detection on the protected link:

The first method is that the physical layer chip of the port of the protected link detects the port rate by itself, and compares the rate with the set standard value. The processor sends an alarm signal to perform fault detection on the protected link. Most of the current POS and Ethernet physical layers have the function of on-off detection.

The second method is generally limited to the situation when the POS port uses the PPP link layer protocol. This condition allows link failure to be detected at the link layer. After the PPP connection is established, the LCP part in the PPP protocol can realize the function of connectivity detection. One side of the PPP connection sends an Echo-Request message to the other party at a certain time interval, and the other party must respond with an Echo-Reply message after receiving the Echo-Request. The sender of the Echo-Request can judge whether the connection is on or off by receiving the Echo-Reply. If the Echo-Reply is received, it can be judged that the link is not faulty, and if the Echo-Reply is not received, the link is considered to be faulty.

All these detection methods are combined with a fault detection mechanism that can realize MPLS fast protection switching, so that ports supporting MPLS fast protection switching can quickly detect link faults.

(3) When a fault is detected in the previous step, the fault is not reported to the IP layer for processing, and the IP layer sends the data to the port of the link fault as usual. The faulty port returns the data sent to the faulty port to the port that sent the data after adding the label switching path mark, and the central processor of the port that sends the data identifies the information carried by the protection label, The information sends the data to the router with the faulty port through the label switching path, and the router at the faulty port exchanges the top-level label, releases the target port information of the protection label, and exchanges it with the information of the faulty port.

If the link to be protected fails again, it is impossible to implement effective protection at this time. In order to prevent the data of a faulty link from being switched to the protection label switching path and then looped back from the protection label switching path of another faulty link, the router must be able to identify the protection label switching path to distinguish the data of the protection channel from the normal data. The data cannot be protected twice and must be discarded on the faulty link.

Below we give an example to describe the realization process of the present invention in detail. As shown in Figure 3. Suppose the link to be protected is L1, the routers at both ends are R1 and R2, and the two ports are C1 and C2 respectively. The data flows output from C1 and C2 to L1 are downlink data flows of C1 and C2 respectively, and the data flows from L1 to C1 and C2 are uplink data flows of C1 and C2 respectively. Under normal circumstances, the downstream data flow of C1 reaches C2 through L1 and becomes the upstream data flow of C2.

According to the present invention, a protection link is firstly established for the protected link L1 with the same start point and end point as the protected link: C1 to L2 to other routers to L3 to C4. A protection label switched path is established along the protection link. Before establishing the protection label switching path, a protection label needs to be configured, usually through a register. The central processing unit of the failed port writes the information of which port of the router that sends the data to which port of the router that receives the data is reached by which port of the router that sends the data via which other router transits which protection label switched path to the register by the central processor of the failed port. That is, once the L1 link fails, write the path information from the C3 port via L2 via other routers to the port C4 via L3 to the register, and then switch to this path according to this information during channel switching described later.

When the L1 link fails, the ports C1 and C2 enter the loopback protection state, and the downstream data flow of C1 is encapsulated with the label switching path mark during the link layer encapsulation process, and then looped back to the upstream of C1, and the upstream of C1 reaches the router R1. The central processing unit of router R1 starts to judge the content of the protection label, and reads the path information of the register, in this example, the path information from port C3 via L2 via other routers and finally to port C4 via L3. Router R1 forwards the message from port C3 through link L2 to other routers through the protection label switching path, and then reaches port C4 of router R2 through link L3.

When the protected message arrives at port C4 of router R2, the message is forwarded to port C2 through the switching network through top-level label switching. There is information about the target port in the top-level label. In this process, you only need to remove the information of the actually arrived target port and replace it with the information of the faulty port. Then port C2 forwards the packet to the upstream of C2 in the loopback protection state, which is the same as the normally arriving packet.

If L1 is protected and looped back due to a fiber break, and a fiber break occurs on L2 or L3 or other links again, all protected packets need to be discarded.

Claims (7)

1. A multi-protocol label switching fast protection switching method, which comprises: a. Establish a protection link with the same starting point and end point as the protected link, and establish a protection label switching path along the protection link; b. The port of the protected link performs fault detection on the protected link; c. When a fault is detected in step b, the data sent to the faulty port will be marked with a label switching path and returned to the port that sent the data, and the port that sent the data will forward the data to the port where the faulty port is located through the protection link The router then forwards the data to that failed port via top-level label switching. 2. The MPLS fast protection switching method according to claim 1, characterized in that: in step a, protection label switching paths are respectively established along the forward and reverse directions of the protection link. 3. The multi-protocol label switching fast protection switching method according to claim 1, characterized in that: in step b, the physical layer chip of the port of the protected link detects the port rate by itself, and compares the rate with the Compared with the set standard value, once the rate is lower than the set standard value, an alarm signal is sent to the central processor controlling the port, so as to detect the fault of the protected link. 4. The multi-protocol label switching fast protection switching method according to claim 1, characterized in that: in step b, the protected link is connected with the PPP link layer protocol, and the port that sends the data is connected to the port that receives the data The port that sends the data sends an Echo-Request message at a certain time interval, and the port that receives the data sends an Echo-Reply message back to the port that sent the data after receiving the Echo-Request message, and the port that sends the data passes the test. After receiving the Echo-Reply message, it is judged whether the protected link is faulty. If the message is received, it is judged that the protected link is not faulty. If the message is not received, it is judged that the protected link is faulty. 5. The multi-protocol label switching fast protection switching method according to claim 1, characterized in that: in step a, before establishing a protection label switching path, a protection label is configured for the established protection label switching path, and the protection label Information about which port of the router sending the data is transferred to which port of the router receiving the data is transferred to which protection label switching path via which other router. 6. The multi-protocol label switching fast protection switching method according to claim 5, characterized in that: in step c, after the data sent to the faulty port is marked with a label switching path and returned to the port that sent the data, The central processor of the port that sends the data identifies the information carried by the protection label, and sends the data to the router at the faulty port through the label switching path according to the information carried by the protection label, and the router at the faulty port performs top-level label exchange, Release the target port information of the protection label and replace it with the information of the faulty port. 7. The multi-protocol label switching fast protection switching method according to claim 6, characterized in that: in step a, the method of configuring the protection label for the established protection label switching path is to configure a register, and the faulty port The central processing unit of the computer writes information about which port of the router that sends the data to which port of the router that receives the data is reached from which port of the router that sends the data via which other router transits which protected label switching path to the register.

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