WO2009046652A1

WO2009046652A1 - Link state detecting method and network device

Info

Publication number: WO2009046652A1
Application number: PCT/CN2008/072349
Authority: WO
Inventors: Yong Tang; Liang Chen
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-09-30
Filing date: 2008-09-12
Publication date: 2009-04-16
Also published as: CN101136810A

Abstract

A link state detecting method and a network device are disclosed. The link state detecting method includes multiple steps. When a main link is in a fault state, a source end of the main link receives messages transmitted from a destination end of the main link from a reversing link. If the source end receives a checkout message transmitted from the destination end during a first fixed period and does not receive a specific message transmitted from the destination end, or if the source end receives the checkout message transmitted from the destination end during a second fixed period, it is determined that the main link changes from the faultstate to a normal state.

Description

Link state detection method and network device

This application claims priority to Chinese Patent Application No. 200710151391.7, entitled "Detection Method of Link Status and Network Equipment," filed on September 30, 2007, the entire contents of which are incorporated by reference. In this application.

Technical field

The present invention relates to the field of network communication technologies, and in particular, to a link state detection method and a network device.

Background technique

OAM (Operation and Maintenance) based on Multiprotocol Label Switching (MPLS) is a link detection technology defined by the International Telecommunications Union (ITU) standard.

The link detection technology based on the MPLS OAM protocol in the prior art is implemented as follows: The source periodically sends a probe packet to the sink, and the sink determines the detected label switched path (LSP) according to the received probe packet. The label switch path is faulty. If the specified number of probe packets cannot be received within a fixed period of the sink, or if the number of probe packets received exceeds the specified number, the detected LSP is faulty. The sink sends a reverse defect indication (BDI) message to the source through the reverse LSP, notifying the detected LSP that the fault is detected, and triggering the source to start the corresponding protection mechanism, such as protection switching. If the source does not receive the BDI packet for 3 consecutive cycles, the device will exit the defect state and trigger the protection switchover, that is, the backup LSP is switched to the detected LSP. The detected LSP is usually called the primary LSP. . The detection packet sent by the source is CV (Connective Verification) or Fast Failure Detection (FFD).

Summary of the invention

The technical problem to be solved by the embodiments of the present invention is to provide a link state detection method and a network device, which can accurately determine the state of the primary link.

To solve the above technical problem, an aspect of the embodiment of the present invention provides a method for detecting a link state, where the method includes: a packet sent by a sink end; If the source end receives the verification packet sent by the sink end in the first fixed period and does not receive the specified packet sent by the sink end, or if the source end is in the second fixed period Upon receiving the verification packet sent by the sink, it is determined that the primary link is restored from the fault state to the normal state.

The source end of the embodiment of the present invention needs to detect whether the verification packet sent by the sink end is received in a fixed period, and whether the specified packet sent by the sink end is not received. When the reverse link is gradually recovered from the fault state to the normal state, the embodiment of the present invention can more accurately determine whether the primary link is in a fault state or a normal state, thereby avoiding false failback. In turn, business traffic is not interrupted.

The embodiment of the invention further provides a network device, where the network device includes:

a first receiving unit, configured to receive, when the primary link is in a fault state, a packet sent by a sink of the primary link from a reverse link;

a first detecting unit, configured to determine, in a fixed period, whether to receive the verification packet sent by the sink, and whether the specified packet sent by the sink is not received, and the verification packet is received When the specified message is not received, the main link is detected to be restored from the fault state to the normal state.

The embodiment of the invention also provides a network device, including:

a second receiving unit, configured to receive, when the primary link is in a fault state, a packet sent by a sink of the primary link from a reverse link;

And a second detecting unit, configured to determine, in a fixed period, whether the verification message sent by the sink end is received, and when the verification message is received, detecting that the main link is restored from a fault state to a normal state.

The embodiment of the invention further provides a network device, including:

Means for receiving a message sent by a sink of the primary link from a reverse link when the primary link is in a fault state;

When it is detected that the check packet sent by the sink end is received in the first fixed period, and the specified packet sent by the sink end is not received, or the sink end is received in the second fixed period. When the verification packet is sent, the unit that restores the primary link from the fault state to the normal state is determined.

The embodiment of the present invention further provides a link state detection system, including a source end and a sink end connected by a primary link and a reverse link, where the sink end is configured to detect that the primary link fails. Sending the specified packet to the source end by using the reverse link, and sending the verification packet when the specified packet is stopped. The embodiment of the present invention can accurately obtain the state of the primary link by detecting whether the verification packet sent by the sink end is received in a fixed period, thereby avoiding error back-cutting, and thus the service traffic is not interrupted.

DRAWINGS

1 is a flowchart of a method for processing a source end according to an embodiment of the present invention;

2 is a flowchart of a method for processing a sink end according to an embodiment of the present invention;

3 is a flowchart of a method for detecting a link state according to an embodiment of the present invention;

4 is a schematic diagram of a network device according to Embodiment 2 of the present invention;

FIG. 5 is a schematic diagram of a network device according to Embodiment 3 of the present invention.

detailed description

In the process of implementing the present invention, the inventors have found that at least the following problems exist in the prior art: Since the transmission of the BDI packet depends on the reverse LSP, if the reverse LSP enters the defect state, the source end is caused to the primary LSP under certain conditions. The status of the error is incorrectly judged and triggers an incorrect failback, causing traffic to be interrupted. The invention can be better understood by the following description of the embodiments of the invention.

Referring to FIG. 1, FIG. 1 is a flowchart of a method for processing a source end according to an embodiment of the present invention. As shown in FIG. 1, if the source end supports the extended function, the source terminal exits the defect to determine that the extended BDI is received within three cycles. -BDI) The message did not receive the corresponding BDI message. The method includes:

101. Reset all timers, that is, reset timers T3 and Τ4.

102. Determine whether a BDI message is received, and if yes, execute 103, otherwise return to execution 101.

103. Stop all reverse metrics. Reverse metrics are parameters that measure the performance of the primary link in reverse.

104. Timer Τ3 starts timing.

105. Determine whether the timer Τ3 is less than 13 cycles, if yes, execute 106, otherwise execute 110.

106. Determine whether the source supports extension. If yes, execute 107, otherwise execute 108.

107. Determine whether an E-BDI message is received, and if yes, execute 108, otherwise return to execution 105.

108. Determine whether the BDI message is not received within 3 cycles. If yes, execute 109, otherwise return to execution 105.

109. Reset all reverse metrics, that is, reset the parameters that measure the performance of the primary link in reverse, and then return to execution 101. 110. The timer T3 stops counting, and the timer Τ4 starts timing.

111. Determine whether the source end supports the extended function. If yes, execute 112, otherwise execute 113.

112. Determine whether an E-BDI message is received within a fixed period. If yes, execute 113, otherwise return to execution 111. Among them, the MPLS ΟΑΜ protocol usually defines a fixed period as three consecutive periods.

113. Determine whether a BDI message is not received within a fixed period. If yes, execute 114, otherwise return to execution 111. The fixed period is consistent with the fixed period of 112.

114. Determine whether the BDI message is not received within 10 consecutive periods. If yes, execute 115, otherwise execute 116.

115. Timer T4 stops timing.

116. Determine whether the source end receives the BDI message, and if yes, return to execute 114, otherwise return to execute.

111.

Referring to FIG. 2, FIG. 2 is a flowchart of a processing method of a sink end according to an embodiment of the present invention. As shown in FIG. 2, when the sink end exits from the defect state, the judgment of whether the extended function is supported is added, and if the extension is supported, the sending is stopped. Forward Defect Indication (FDI) message and BDI message, triggering the transmission of E-BDL3⁄4 text and entering the branch processing flow after E-BDI transmission; if extension is not supported, the procedure is as specified in the original protocol. deal with. The method includes:

201. Reset the timers T1 and Τ2.

202. Determine whether a defect is detected. If yes, execute 203, otherwise return to execution 201.

203. Determine whether the sink end receives the FDI packet sent by the source end, if yes, execute 205, otherwise execute 204, generate a defect warning, and then execute 205.

205. The sink sends the FDI packet and the BDI packet to the source end.

206, timer T1 starts timing.

207. Determine whether T1 is less than 10 cycles. If yes, execute 208, otherwise execute 212.

208. Determine whether the defect is over. If yes, execute 209, otherwise return to execution 207.

209. Determine whether the sink supports the extended function. If yes, execute 210, otherwise execute 211.

210. Stop sending FDI messages and BDI messages, send E-BDI packets at the same time, and then execute 201.

211. Stop sending FDI messages and BDI messages, and then execute 201.

212. Timer T1 stops timing, and timer Τ2 starts timing.

213. Determine whether the defect is ended. If yes, execute 214, otherwise continue to perform 213. 214. Determine whether the sink supports the extended function. If yes, execute 215, otherwise stop sending the FDI to the text and the BDI text.

215. Stop sending FDI messages and BDI messages, and send E-BDI packets at the same time.

216. Determine whether 9 to 11 expected CV messages are received within 10 cycles, and no undesired messages are received. If yes, execute 217, otherwise execute 219.

217. Timer T2 stops timing.

218. Reset all metrics, that is, parameters that measure the performance of the primary link.

219. Determine whether a defect is detected. If yes, execute 220, and then execute 213, otherwise execute

220.

220. Send an FDI packet and a BDI packet to the source end, and then execute 213.

Embodiment 1 A method for detecting a link state, and a method flowchart is shown in FIG. 3, including:

301. The source end periodically sends a probe packet to the sink through the primary link, where the probe packet may be a CV or FFD packet.

302. The sink determines whether the probe packet is not received in the fixed period, or the specified packet received exceeds the specified number. If yes, execute 303, otherwise the process ends.

303. The primary link is faulty, and the sink sends a packet to the source through the reverse link to notify the status of the primary link. The sent packet is a check packet, a specified packet, and the like, and the check packet is an E-BDI packet or an arbitrary packet stipulated by the source end and the sink end, and the specified packet may be a BDI report. Text or fault detection message, etc.

304. The source end determines whether the verification packet sent by the sink end is received in a fixed period, and if yes, execute

305, otherwise the main link is still in a fault state, and the process ends.

305. The source end determines whether the specified packet sent by the sink end is not received in the fixed period. If yes, the main link is restored from the fault state to the normal state, and the source end triggers the protection switching back to cut, so that the traffic is from the backup chain. The road switches to the primary link, otherwise the process ends.

306. The source end sends an acknowledgement packet to the sink end to indicate that the check packet sent by the sink end has been received.

The first embodiment is a preferred embodiment of the present invention. When the reverse link of the embodiment goes from a fault state to a normal state, the source end may receive a BDI packet, and may not receive a BDI packet. If the verification packet is received, the verification packet may not be received. Therefore, it is necessary to determine the reception status of the two types of packets to accurately determine the status of the primary link. It is worth noting that if the reverse link is in the normal state or the fault state, when the primary link returns to the normal state, the source end cannot receive the BDI packet. In this case, it is determined whether the source end receives the calibration within a fixed period. The message can be informed of the status of the primary link.

It is also to be noted that the verification message in the embodiment of the present invention may be an E-BDI message, and may also be any message stipulated by the source end and the sink end, for example, a 1-byte all-zero message or all 1 message, etc. The FFD (E-FFD) message of the exhibition can also be any message stipulated by the source end and the sink end.

Finally, the source end and the sink end of the embodiment of the present invention may be a label switching router, or a router or other network equipment without label switching capability, and the primary link and the reverse link may be label switching paths or none. Routing of label switching capabilities, etc.

The expansion of BDI packets, CV packets, and FFD packets is described below in conjunction with Table 1, Table 2, and Table 3. The extension of the packet involves two parts:

1 ) , type ( Type ) field

The type field of the BDI packet is 03H, the type field of the CV packet is 01H, and the type field of the FFD packet is 02H. After the extension, the type fields of the E-CV, E-FFD, and E-BDI use 00H, that is, The type of the reservation in the OAM protocol packet is used to identify the packet as an extended packet. If the source or the sink supports the extended function, the packet is sent to the extended packet after receiving the packet. If the source or sink does not support the extension, the packet will be discarded. This will not affect the original function and ensure compatibility.

2) , Reserve (Reserve) field

The reserved fields of BDI, CV and FFD messages are all 00H. After expansion, the reserved field of E-BDI is 01H, the reserved field of E-CV is 02H, and the reserved field of E-FFD is 03H, which distinguishes three extensions. Protocol message. The Defect Type and Defect Location fields involved in each extended packet are not processed, and the processing of other fields of the packet is not changed to ensure the unique correspondence between the extended protocol packet and the LSP. Relationship and the reliability of the message.

The extended BDI, CV and FFD messages are as follows: 0 7 15 23 31 Type field (00H) Reserved field (01H) Defect type tracking network device source identifier

Defect location padding field

16-bit cross parity

Table 1

0 7 15 23 31 Type field (00H) Reserved field (02H) Track network device source identifier

Defect location padding field

16-bit cross parity

Table 2 0 7 23 31 Type field (00H) Reserved field (03H) Defect type tracking network device source identifier

Defect location

table 3

It will be understood by those skilled in the art that all or part of the methods for implementing the above embodiments may be implemented by a program indicating related hardware, and the program may be stored in a computer readable storage medium, and when executed, the program includes : The message sent by the sink;

Detecting whether the verification packet sent by the sink is received, and whether the specified packet sent by the sink is not received, and the verification packet is received and the When a packet is specified, it is detected that the primary link is restored from a fault state to a normal state.

In addition, the execution method of the program may include: a message sent by the sink end;

Detecting whether the verification packet sent by the sink is received in a fixed period, and detecting that the primary link is restored from a fault state to a normal state when the check packet is received.

The storage medium may be a ROM, a RAM, a magnetic disk or an optical disk, or the like.

Embodiment 2 A network device, as shown in FIG. 4, the network device includes a first receiving unit 401, a first detecting unit 402, and a transmitting unit 405.

The first receiving unit 401 is configured to receive, when the primary link is in a fault state, the packet sent by the sink end of the primary link from the reverse link; The first detecting unit 402 includes:

The first judging unit 403 is configured to determine, in a fixed period, whether the check packet sent by the sink end is received, where the check packet may be an E-BDI packet, or may be a source end and a sink end agreement. Any of the messages, for example, 1 byte of the whole (^艮文 or 艮文, etc.).

The second determining unit 404 is configured to determine, when the verification packet is received in a fixed period, whether the specified packet sent by the sink is not received, and detect that the primary link is faulty when the specified packet is not received. The state is restored to the normal state, and the specified packet is a BDI packet.

The sending unit 405 is configured to send the extended connectivity confirmation packet, the fast fault detection packet, or any packet agreed by the source end and the sink end to the sink end after the first receiving unit 401 receives the verification packet.

Implementation 3: A network device, as shown in FIG. 5, the network device includes:

The second receiving unit 501 is configured to receive, when the primary link is in a fault state, the packet sent by the sink of the primary link from the reverse link.

The second detecting unit 502 is configured to determine, in a fixed period, whether the verification packet sent by the sink end is received, and when the verification packet is received, detecting that the primary link is restored from the fault state to the normal state.

The second sending unit 503 is configured to send the extended connectivity confirmation packet, the fast fault detection packet, or any packet agreed by the source end and the sink end to the sink end after the second receiving unit 501 receives the verification packet.

It should be noted that the above may further include a module for timing, such as a timer, and the timing module may be integrated with the first detecting unit or the second detecting unit, or may be used as a single module.

It is also worth noting that the network device can be implemented by software or hardware modules having the same or corresponding functions in addition to the implementation methods provided in the second embodiment and the third embodiment.

In summary, the source end of the embodiment of the present invention needs to detect whether the check packet sent by the sink end is received in a fixed period, and whether the specified packet sent by the sink end is not received, and In the embodiment of the present invention, when the reverse link gradually recovers from the fault state to the normal state, the embodiment of the present invention can more accurately determine that the primary link is faulty. The status is still normal, so that error back-cutting can be avoided, so that traffic is not interrupted.

In addition, since the BDI packet is not sent in the faulty or normal state, the state of the primary link is incorrectly determined. In this embodiment, the embodiment of the present invention detects whether the device is received in a fixed period. The check packet sent by the sink end can accurately obtain the state of the primary link, thereby avoiding Error-free back-cutting, so that business traffic will not be interrupted.

The description of the above embodiments is only for helping to understand the method of the present invention and its core idea; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in specific embodiments and applications. In summary, the content of the specification should not be construed as limiting the invention.

Claims

Rights request

A method for detecting a link state, where the method includes: a packet sent by a sink end;

If the source end receives the verification packet sent by the sink end in the first fixed period and does not receive the specified packet sent by the sink end, or if the source end is in the second fixed period Upon receiving the verification packet sent by the sink, it is determined that the primary link is restored from the fault state to the normal state.

2. The method according to claim 1, wherein the method further comprises: after detecting, by the sink, that the primary link fails, transmitting the specified packet through the reverse link.

The method according to claim 2, wherein the method further comprises: when the sink stops transmitting the specified packet, sending the verification packet.

The method according to claim 3, wherein the method further comprises: determining, before the sending end of the verification message, whether the sink end supports an extended function, and if yes, executing Sending the verification packet.

The method according to any one of claims 1 to 4, wherein the verification message is an extended reverse defect indication message or an arbitrary message agreed by the source end and the sink end.

The method according to any one of claims 1 to 4, wherein the specified message is a reverse defect indication message or a failure detection message.

A network device, which is used as a source end of a primary link, the network device includes: a first receiving unit, configured to receive, by the reverse link, when the primary link is in a fault state a packet sent by a sink of the primary link;

The network device according to claim 7, wherein the first detecting unit comprises: a first determining unit, configured to determine whether the check message is received in a fixed period; When the verification packet is received in a fixed period, it is determined whether the specified packet is not received, and when the specified packet is not received, the main link is detected to be restored from the fault state to the positive state. Constant state.

The network device according to claim 7 or 8, wherein the network device further comprises:

The sending unit is configured to send the extended connectivity confirmation packet, the fast fault detection packet, or any packet agreed by the source end and the sink end to the sink end after the first receiving unit receives the verification packet.

A network device, configured to be used as a source of a primary link, the network device, comprising: a second receiving unit, configured to receive, when the primary link is in a fault state, receive from a reverse link a packet sent by a sink of the primary link;

11. A network device, characterized by comprising:

12. A link state detection system, comprising: a source end and a sink end connected by a primary link and a reverse link, wherein:

The sink end is configured to: after detecting that the primary link fails, send a specified text to the source end by using the reverse link, and send a check when stopping the sending of the specified “3⁄4 text” 3⁄4 text.

The system according to claim 12, wherein the sink is further configured to determine whether the sink supports an extended function before sending the check packet, and if yes, perform the sending The verification message.

14. The system of claim 13 wherein:

The source end is configured to receive, when the primary link is in a fault state, the packet sent by the sink end of the primary link from the reverse link, and detect that the sent by the sink end is received in the first fixed period. Determining that the primary link is restored from a fault state when the packet is received and the specified packet sent by the sink is not received, or when the check packet sent by the sink is received in the second fixed period. To normal state.