WO2008095381A1

WO2008095381A1 - Method for sending label distribution protocol information and label switching router

Info

Publication number: WO2008095381A1
Application number: PCT/CN2007/070435
Authority: WO
Inventors: Min Peng
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-02-05
Filing date: 2007-08-08
Publication date: 2008-08-14
Also published as: CN100550855C; CN101009654A

Abstract

A method for sending label distribution protocol information includes determining whether the ongoing LDP information has Hop Count TLV, if yes, modifying said LDP before sending it out, otherwise, sending said LDP directly. Said method guarantees the reception of the LDP by the receiver, and ensures the normal establishment of the LSP. A LSR for sending said LDP information is also presented.

Description

Method for transmitting label distribution protocol message and label switching router

Technical field

The invention relates to a method for multiprotocol label switching (MPLS) messages and a Label Switching Router (LSR). Background of the invention

On an MPLS network, LDP messages are transmitted between different LSRs to establish a Label Switching Path (LSP). Most LDP messages are encapsulated by a Type Length Value (TLV) scheme. Each LDP message contains one or more mandatory or optional TLVs. Each TLV can be divided into a 4-byte common TLV header unit and a variable-length value domain unit. The format of TLV is shown in Table 1:

Table 1

In the structure definition of the TLV, the unknown TLV bit (U bit ) is used to: when an LDP message received by an LSR in the MPLS network includes an unrecognizable TLV, if the T bit of the TLV The value is a predefined value of the ignoring LDP message, that is, equal to 0, then the LSR ignores the entire LDP message and returns a notification message to the LSR that sent the LDP message; if the U bit of the TLV The value is a predefined value that ignores the TLV, that is, equal to 1. The operation is to ignore the TLV, and the other part of the LDP message containing the TLV will be processed normally, and the LSP can be established normally.

In different types of LDP messages, the Label Request message and the Label Mapping message can be hop-by-hop along the LSP. Therefore, the TLV carried by the LDP messages can record the information along the LSP and implement the loop. Detection. The hop count TLV ( Hop Count TLV ) is an optional parameter in the label request message or the label mapping message. The hop count TLV records the number of hops along the LSP. When the hop count exceeds the previously configured value, it indicates that a loop occurs.

In the prior art, if an LSR supports loop detection, the label request message or the label mapping message sent by the LSR must carry the hop count TLV, and the value of the U bit of the hop count TLV is fixed to the predefined LDP ignoring. The corresponding value of the message, which is equal to 0, does not take into account the situation when the receiver of the message does not support loop detection. If the receiving end of the message does not support the loop detection itself, the hop count TLV in the received message cannot be identified, and because the U bit of the hop count TLV is fixed to ignore the corresponding value of the LDP message, that is, 0, the whole The LDP message will be ignored and will not be processed. The LDP message cannot be established because the LDP message is related to the label request message or the label mapping message. It can be seen that the setting of the LDP message sent in the prior art may affect the identification of the entire LDP message by the receiving end and affect the normal establishment of the LSP. Summary of the invention

In this regard, the embodiment of the present invention provides a method for transmitting an LDP message, and the LDP message sent by the method can ensure the normal establishment of the LSP.

The embodiment of the present invention further provides an LSR that sends an LDP message, and the LDP message sent by the LSR can ensure the normal establishment of the LSP. In order to achieve the above object, the technical solution of the present invention is implemented as follows:

A method for transmitting an LDP message, the method includes: determining whether the LDP message to be sent includes a hop count TLV: if yes, modifying the LDP message, and sending the modified LDP message; if not, directly Send the LDP message.

An LSR that sends LDP messages. The LSR includes:

a hop count TLV judging module, configured to determine whether the LDP message to be sent includes a hop count TLV: if yes, send a modify command to the LDP message processing module; if not, send the LDP message processing module to the LDP message processing module Modify the command;

The LDP message processing module is configured to: modify the LDP message according to the received modification command, and send the modified LDP message to the LDP message sending module; send the LDP message to the LDP message according to the received no modification command. Module

The LDP message sending module is configured to send the received LDP message.

It can be seen that the method for transmitting an LDP message and the LSR proposed by the embodiment of the present invention can modify and send the LDP message, and the LDP message sent by the method does not affect the normal establishment of the LSP. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a basic flowchart of sending an LDP message according to an embodiment of the present invention;

2 is a flowchart of a specific implementation of sending an LDP message according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an LSR that sends an LDP message according to an embodiment of the present invention. Mode for carrying out the invention

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

The present invention provides a method of transmitting an LDP message. Referring to Figure 1, Figure 1 is a A basic flow chart for sending an LDP message.

Step 101: Determine whether the LDP message to be sent includes the hop count TLV: if yes, go to step 102; if not, go to step 103.

Step 102: Modify the LDP message.

Step 103: Send an LDP message.

In the foregoing method, the method for modifying the LDP message in the step 102 may be: modifying the value of the U bit of the hop count TLV in the LDP message to: a corresponding value of the predefined hop count TLV, that is, equal to 1. After the modification, if the receiving end does not recognize the hop count TLV, only the hop count TLV will be discarded without affecting the identification of the entire LDP message.

Before the label request message or the label mapping message is transmitted between the two LSRs, an LDP session (Session) needs to be established between the two LSRs. When an LDP session is established, each LSR uses an Initialization message to advertise the other party. Whether it supports loop detection itself. The initialization message carries a loop detection bit (D bit), which is used to indicate whether the LSR that sends the initialization message supports loop detection. If the value of the D bit is a predefined value supporting the loop detection, that is, equal to 1, it indicates that the LSR supports loop detection; if the value of the D bit is a predefined value that does not support loop detection, it is equal to 0. , indicating that the LSR does not support loop detection. If an LSR itself supports loop detection, the LSR can identify the hop count TLV when it receives the LDP message carrying the hop count TLV. If an LSR does not support loop detection, the LSR receives the bearer. When the LDP message of the TLV is counted, the hop count TLV cannot be recognized. Therefore, before the LDP message is sent, the LDP message can be modified according to whether the receiving end can recognize the hop count TLV.

In this manner, when the LDP message to be sent includes the hop count TLV, the method may further include: determining whether the receiving end of the LDP message can identify the hop count TLV: if not, modifying the LDP message, the modification The latter LDP message is sent out; if it can be identified, the LDP message is directly sent. In the foregoing method, the manner of modifying the LDP message may be: modifying the value of the U bit of the hop count TLV in the LDP message to: a corresponding value of the predefined hop count TTL, that is, equal to 1. Or, delete the hop count TLV in the LDP message.

In the foregoing method, the method for determining whether the receiving end of the LDP message can identify the hop count TLV may be: determining whether the value of the D bit in the initialization message sent by the receiving end of the LDP message is a preset support loop detection. The corresponding value, which is equal to 1:

If yes, the receiving end of the LDP message can identify the hop count TLV;

If not, the receiving end of the LDP message cannot recognize the hop count TLV.

Referring to FIG. 2, FIG. 2 is a flowchart of a specific implementation of sending an LDP message according to an embodiment of the present invention. Step 201: Determine whether the LDP message to be sent includes a hop count TLV: if yes, perform step 202; if not, perform step 204.

Step 202: Determine whether the receiving end of the LDP message can identify the hop count TLV: If not, go to step 203; otherwise, go to step 204.

Step 203: Delete the hop count TLV in the LDP message, and continue to step 204;

Step 204: Send an LDP message.

In the foregoing step 202, the method for determining whether the receiving end of the LDP message can identify the hop count TLV may be:

Determining whether the D bit in the initialization message sent by the receiving end of the LDP message is a corresponding value of the preset support loop detection, that is, equal to 1: If yes, the receiving end of the LDP message can identify the hop count TLV; , it is not recognized.

The present invention also proposes an LSR that transmits an LDP message. Referring to FIG. 3, FIG. 3 is a schematic structural diagram of an LSR that sends an LDP message according to an embodiment of the present invention. The LSR includes: a hop count TLV judging module 301, an LDP message processing module 302, and an LDP message sending module 303;

The hop count TLV judging module 301 is configured to determine whether the LDP message to be sent includes a hop count TLV: if yes, send a modification to the LDP message processing module 302. If not included, sending the LDP message processing module 302 to the LDP message processing module 302 without modifying the command; the LDP message processing module 302 is configured to modify the LDP message according to the received modification command, and send the modified LDP message to the The LDP message sending module 303: sends the LDP message to the LDP message sending module 303 according to the received no-modification command, and the LDP message sending module 303 is configured to send the received LDP message. In the above LSR, the LDP message processing module 302 may include: a receiving end determining submodule 3021 and a processing submodule 3022;

The receiving end determining sub-module 3021 is configured to: after receiving the modification command, determine whether the receiving end of the LDP message can identify the hop count TLV, and if yes, send the processing sub-module 3022 without the modification command, if not, Sending a modification command to the processing sub-module 3022; or, when receiving the no-modification command, forwarding the modification command to the processing sub-module 3022;

The processing sub-module 3022 is configured to: modify the LDP message according to the received modification command, and send the modified LDP message to the LDP message sending module 303; or send the LDP message to the LDP message according to the received no modification command. The LDP message sending module 303.

In the foregoing LSR, the LDP message processing module 302 is configured to modify the value of the U bit of the hop count TLV in the LDP message to a corresponding value of the predefined ignore hop count TLV according to the received modification command, and the modified LDP The message is sent to the LDP message sending module. Here, the predefined value of the ignoring hop count TLV can be 0.

In the LSR, the processing sub-module 3022 is configured to delete the TTL of the hop in the LDP message according to the received modification command, or modify the value of the U bit of the TTL of the LDP message to a predefined hop count TLV. The LDP message is sent to the LDP message sending module 303.

In the foregoing LSR, the receiving end determining module 3021 is configured to determine whether the value of the D bit in the initialization message sent by the receiving end of the LDP message is a preset support loop check. The corresponding value measured, that is, equal to 1:

If yes, the receiving end of the LDP message can identify the hop count TLV;

It can be seen that the method for transmitting an LDP message and the LSR according to the embodiment of the present invention can modify the LDP message to be sent, and the modification manner can be: Modify the U bit of the hop count TLV in the LDP message to a predefined ignore. The corresponding value of the hop count TLV; or according to whether the receiving end of the LDP message can identify the hop count TLV to delete or retain the hop count TLV in the LDP message. After the LDP message is sent out, whether the LDP message receiving end can identify the hop count TLV does not affect the identification of the entire LDP message and ensures the normal establishment of the LSP.

Claims

Claim

A method for transmitting a label distribution protocol LDP message, the method comprising:

Determining whether the LDP message to be sent includes the hop type length value TLV: If yes, the LDP message is modified, and the modified LDP message is sent; if not, the LDP message is directly sent.

The method according to claim 1, wherein when determining that the LDP message to be sent includes the hop count TLV, the method further includes:

Determining whether the receiving end of the LDP message can identify the hop count TLV: If the LDP message is not recognized, the LDP message is modified, and the modified LDP message is sent out; if it can be identified, the LDP message is directly sent.

The method according to claim 1 or 2, wherein the manner of modifying the LDP message is:

The value of the unrecognized TLV bit U bit of the hop count TLV in the LDP message is modified as: The corresponding value of the predefined hop count TLV.

The method according to claim 2, wherein the modifying the LDP message is: deleting the hop count TLV in the LDP message.

The method according to claim 2, wherein the manner of determining whether the receiving end of the LDP message can identify the hop count TLV is:

Determining whether the value of the loop detection bit D bit in the initialization message sent by the receiving end of the LDP message is a preset value of the support loop detection:

If yes, the receiving end of the LDP message can identify the hop count TLV;

A label switching router LSR that transmits an LDP message, characterized in that the LSR include:

The LDP message processing module is configured to: modify the LDP message according to the received modification command, and send the modified LDP message to the LDP message sending module; or send the LDP message to the LDP according to the received no modification command. Message sending module;

The LDP message sending module is configured to send the received LDP message.

The LSR according to claim 6, wherein the LDP message processing module comprises:

The receiving end determining sub-module is configured to: after receiving the modification command, determine whether the receiving end of the LDP message can identify the hop count TLV, and if yes, send a no-modification command to the processing sub-module, if not, to the processing sub-module The module sends a modification command; or, when the command does not need to be modified, the modification command is forwarded to the processing submodule;

The processing submodule is configured to: modify the LDP message according to the received modification command, and send the modified LDP message to the LDP message sending module; or send the LDP message to the LDP message according to the received no modification command. Send module.

The LSR according to claim 6, wherein the LDP message processing module is configured to modify the value of the U bit of the hop count TLV in the LDP message to a predefined ignore hop according to the received modification command. The corresponding value of the number of TLVs is sent to the LDP message sending module.

The LSR according to claim 7, wherein the processing sub-module is configured to delete a TTL of a TTL in an LDP message according to the received modification command, or a U bit of a TTL of the LDP message The value is modified to a corresponding value of the predefined hop count TTL, and the modified LDP message is sent to the LDP message sending module.

The LSR according to claim 7, wherein the receiving end determining submodule is configured to determine whether the value of the D bit in the initialization message sent by the receiving end of the LDP message is a preset support. Corresponding values for loop detection:

If yes, the receiving end of the LDP message can identify the hop count TLV;