CN102238138A

CN102238138A - Pseudo wire service processing method and system

Info

Publication number: CN102238138A
Application number: CN2010101568964A
Authority: CN
Inventors: 金利忠; 胡侃; 陈保军; 冯健
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2010-04-23
Filing date: 2010-04-23
Publication date: 2011-11-09

Abstract

The invention discloses a pseudo wire service processing method, which comprises the following steps of: negotiating about the consistency of pseudo wire freeze configuration between a local provider edge (PE) and a remote PE in a static configuration or signaling notification way; if a signaling session between the local PE and the remote PE is interrupted or protocol processors of the local PE and the remote PE fail when the local PE and the remote PE are both configured with the freeze attribute of a pseudo wire, continuously keeping the forwarding state of the pseudo wire. The invention also discloses a pseudo wire service processing device. By the method and the device provided by the invention, the service forwarding state of the pseudo wire is continuously kept, and a pseudo wire service corresponding to the signaling session may not be stopped if the signaling session is interrupted or the protocol processors of the local PE and the remote PE fail, thereby ensuring the continuous forwarding of a customer service.

Description

Pseudo wire service processing method and system

Technical Field

The present invention relates to pseudowire technologies in network communications, and in particular, to a method and a system for processing pseudowire services.

Background

The Pseudo Wire (PW) technology is a solution proposed for future converged communication networks, and is a technology for providing a network service simulating the traditional layer 1 and layer 2 networks on a packet-switched network. The pseudo wire technology is almost suitable for all networks including a transmission network and an access network, and can break through a core network by a Multi-Protocol Label switching (MPLS) technology to realize real convergence of the access network and a metropolitan area network.

The pseudowire is a point-to-point connection between Edge routers (PE, Provider Edge), a pseudowire establishment mechanism is defined in RFC4447 of Internet Engineering Task Force (IETF), a Target Label distribution protocol (T-LDP) session is used as a signaling mechanism to establish the pseudowire, and Label exchange and parameter negotiation of the pseudowire are performed. Location of pseudowire, T-LDP session, in the network, as shown in FIG. 1. When a T-LDP session is interrupted due to some failure, the edge router needs to tear down the pseudowire corresponding to the failed session, including releasing the label forwarding information corresponding to the pseudowire, and the customer service carried by the corresponding pseudowire is also interrupted.

The T-LDP session is easily affected by network instability or failure due to the characteristics of the T-LDP session based on Internet Protocol (IP), lacks an effective protection mechanism, and relies on IP for automatic convergence to cause a long convergence time, generally more than 40 seconds. In some cases, the T-LDP session may be independent of the packet-switched network Tunnel (PSN Tunnel) that carries the pseudowire, and when the T-LDP session is interrupted, the PSN Tunnel corresponding to the pseudowire may still be intact. At this time, the interruption of the pseudo wire is caused by the interruption of the T-LDP session, thereby causing the interruption of customer service, and greatly reducing the availability of the pseudo wire.

By using the existing Graceful Restart (Graceful Restart) mechanism to separate the control plane and the forwarding plane of the pseudowire, the forwarding of traffic can be continuously maintained while keeping the traffic uninterrupted when the T-LDP session is interrupted. But the Graceful Restart function is a mechanism designed under the assumption of a Restart of a far-end PE member, thereby limiting its scope to all pseudowire traffic associated with a T-LDP session between two PEs that are peer-to-peer with each other. If a user requires some pseudowire services on a certain T-LDP session, the services need to be maintained when the signaling is interrupted, and for other pseudowire services, the services need to be interrupted when the signaling is interrupted, and then the existing Graceful Restart cannot complete the function. In addition, the existing Graceful Restart has the maximum time limit for the service retention time; that is, when the time of interruption of the T-LDP session exceeds the Restart latency (Restart time) of Graceful Restart, the PE establishing the pseudowire still deletes the pseudowire, so that the service carried by the pseudowire is interrupted. In addition, the smooth restart mechanism can be enabled only in a unit of session, that is, if a session enables the smooth restart mechanism, all pseudowires passing through the session have the smooth restart mechanism. This cannot be done if the user wants only some pseudowires to be independent of the control plane and the forwarding plane.

Virtual Private local area network Service (VPLS) based on a Border Gateway Protocol (BGP) signaling mode, and completes VPLS member automatic discovery, label switching of pseudo wires and parameter negotiation through BGP signaling. The location of the VPLS, pseudowire, BGP signaling session in the network, as shown in fig. 2. When BGP signaling is interrupted due to some failure, the PE members of VPLS delete the corresponding pseudowire labels, thereby causing service interruption of VPLS.

BGP signaling sessions are susceptible to network instability or failure due to their IP nature and lack an effective protection mechanism. In some cases, the BGP signaling session is independent of the packet-switched network tunnels (PSN tunnels) that carry the user traffic, and when the BGP signaling session is interrupted, the PSN tunnels corresponding to the pseudowires between the two VPLS member PEs may still be intact. At this time, the interruption of the pseudowire is caused by the interruption of the BGP signaling session, which causes the interruption of the customer service carried by the pseudowire and greatly reduces the availability of the VPLS.

Disclosure of Invention

In view of the above, the present invention provides a method and a system for processing a pseudo wire service to improve the availability of the pseudo wire.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the invention provides a method for processing pseudo wire service, which comprises the following steps:

negotiating the consistency of pseudo wire freezing configuration between a local edge router (PE) and a far-end PE in a static configuration or signaling notification mode;

when the local PE and the far-end PE are both configured with the freezing attribute of the pseudo wire, if the signaling session between the local PE and the far-end PE is interrupted or the protocol processors of the local PE and the far-end PE fail, the forwarding state of the pseudo wire is continuously maintained.

The signaling session includes: all pseudowire sessions are established based on the target label distribution protocol (T-LDP) and the Border Gateway Protocol (BGP).

The protocol processors of the local PE and the far-end PE have a main and standby protection function or a function of storing pseudo wire information in a Non-Volatile memory (Non-Volatile ROM).

The method further comprises the following steps:

the local PE and the far-end PE respectively send pseudo-wire attribute advertisements to the opposite end, and the local PE and the far-end PE respectively judge whether the opposite end is configured with the freezing attributes of the pseudo-wires through the received pseudo-wire attribute advertisements, and further judge whether the pseudo-wire freezing configurations of the local PE and the far-end PE are consistent.

The method for negotiating the consistency of pseudo wire freezing configuration between the local PE and the far-end PE in a signaling notification mode specifically comprises the following steps:

configuring a freezing attribute of a pseudo wire on a local PE, notifying the freezing attribute to a far-end PE through a signaling session, configuring the freezing attribute by the far-end PE according to a received signaling session, and sending a pseudo wire attribute notification to the local PE; or,

the method comprises the steps that a freezing attribute of a pseudo wire is configured on a far-end PE, the freezing attribute is notified to a local PE through a signaling session, and the local PE configures the freezing attribute according to a received signaling session and sends the pseudo wire attribute notification to the far-end PE.

Negotiating that the pseudo wire freezing configuration is consistent between the local PE and the far-end PE in a signaling notification mode, specifically comprising:

configuring a freezing attribute on the local PE or the far-end PE, and sending the configured freezing attribute to the PE of the opposite end in a signaling notification mode, wherein the PE of the opposite end configures according to the received freezing attribute;

or, the local PE and the far-end PE configure the freezing attribute respectively, and send the configured freezing attribute to the PE of the opposite end in a signaling notification manner, and the local PE and the far-end PE negotiate the consistency of the configuration of the freezing attribute.

After the local PE and the far-end PE are both configured with the frozen attribute of the pseudowire, the method further comprises: and the local PE and the remote PE transmit the pseudo wire state information through a pseudo wire associated channel.

The invention also provides a pseudo wire service processing device, which is applied to the local PE and the far-end PE, and the device comprises:

the configuration module is used for negotiating that the pseudo wire freezing configurations of the local PE and the far-end PE are consistent in a static configuration or signaling notification mode;

and the service processing module is used for continuing to keep the forwarding state of the pseudo wire if the signaling session between the local PE and the far-end PE is interrupted or the protocol processors of the local PE and the far-end PE fail when the local PE and the far-end PE are both configured with the freezing attribute of the pseudo wire.

The signaling session includes: all of the T-LDP and BGP based sessions for pseudowires are established.

The protocol processors of the local PE and the far-end PE have the functions of main and standby protection or the function of storing pseudo wire information in a Non-voice ROM.

The configuration module is further configured to send a pseudo wire attribute advertisement to an opposite end of the PE, and determine whether the opposite end is configured with a frozen attribute of the pseudo wire by receiving the pseudo wire attribute advertisement of the opposite end, thereby determining whether the frozen configurations of the pseudo wires of the local PE and the far-end PE are consistent.

The configuration module is further configured to configure a frozen attribute of the pseudowire, notify the frozen attribute to an opposite end of the PE through a signaling session, and receive a pseudowire attribute notification sent by the opposite end.

The configuration module is further configured to configure a freezing attribute on the local PE or the far-end PE, send the configured freezing attribute to the PE of the opposite end in a signaling notification manner, and trigger the PE of the opposite end to perform configuration according to the received freezing attribute;

or, respectively configuring the freezing attributes on the local PE and the far-end PE, and sending the configured freezing attributes to the PE of the opposite end in a signaling notification manner, triggering the local PE and the far-end PE to negotiate the consistency of the configuration of the freezing attributes.

The service processing module is further configured to transmit pseudowire state information between the local PE and the remote PE through the pseudowire association channel after the local PE and the remote PE are both configured with the frozen attribute of the pseudowire.

The invention provides a method and a system for processing pseudo wire service, which negotiate the consistency of pseudo wire freezing configuration between a local PE and a far-end PE in a static configuration or signaling notification mode; when the local PE and the far-end PE are both configured with the freezing attribute of the pseudo wire, if the signaling session between the local PE and the far-end PE is interrupted or the protocol processors of the local PE and the far-end PE fail, the forwarding state of the pseudo wire is continuously maintained, so that the control plane and the forwarding plane of the pseudo wire are completely separated. By the invention, when the signaling session (including all the sessions for establishing the pseudo wires based on the T-LDP and the BGP) is interrupted or the protocol processors of the local PE and the far-end PE fail, the pseudo wires are enabled to continuously keep the service forwarding state, and the pseudo wire service corresponding to the signaling session is not removed, thereby ensuring the continuous forwarding of the customer service and improving the availability of the pseudo wires.

Drawings

FIG. 1 is a schematic diagram of the location of a pseudowire, T-LDP session in a network in the prior art;

fig. 2 is a schematic diagram of the locations of VPLS, pseudowires, and BGP signaling sessions in a network in the prior art;

FIG. 3 is a flowchart of notifying the pseudowire frozen attribute through a T-LDP session according to an embodiment of the present invention;

FIG. 4 is a flowchart of advertising a pseudowire frozen attribute by static configuration according to an embodiment of the present invention;

FIG. 5 is a flowchart illustrating an embodiment of the present invention, wherein a freezing attribute is configured only in a single-side PE, and a T-LDP session announces the freezing attribute of a pseudo wire to a far-end PE;

fig. 6 is a flowchart of notifying VPLS freezing attribute by crossing BGP signaling session according to an embodiment of the present invention;

fig. 7 is a flowchart of notifying the VPLS freeze attribute through static configuration in an embodiment of the present invention;

fig. 8 is a flowchart of sixth embodiment of the present invention, in which a freezing attribute is configured only in a single-side PE, and a BGP session notification VPLS freezes the attribute to a remote PE.

Detailed Description

The technical solution of the present invention is further elaborated below with reference to the drawings and the specific embodiments.

Considering the pseudowire establishment and teardown mechanisms provided by RFC4447 and RFC4761 of IETF, the customer service carried by the pseudowire is easily affected by signaling session fluctuation, and the availability of the pseudowire is reduced. Therefore, the invention provides a mechanism for improving the availability of the pseudo wire, aiming at ensuring that the pseudo wire continuously keeps the service forwarding state when the signaling session is interrupted, and the pseudo wire service corresponding to the signaling session is not removed, thereby ensuring the continuous forwarding of the customer service.

The invention is based on the following core idea: the signaling session is interrupted, or the protocol processors of the local PE and the remote PE fail, and the forwarding capability of the PW may still be maintained; thereby proposing a Freeze (Freeze) state and an Unfreeze (Unfreeze) state of the PW, wherein the forwarding capability of the PW in the Freeze state is not influenced by a signaling session or the failure of protocol processors of the local PE and the remote PE; the forwarding capability of the PW in the Unfreeze state will be affected by the failure of the protocol processors of the local PE and the remote PE, or the signaling session. The failure of the protocol processors of the local PE and the remote PE means that at least one of the protocol processors of the local PE and the remote PE has failed.

Based on the above thought, the processing method of the pseudo wire service provided by the invention mainly comprises the following steps:

step 201, negotiation is performed between the local PE and the remote PE in a static configuration or signaling notification manner to ensure consistent pseudowire freezing configuration.

The static configuration means that the same frozen attribute is statically configured at the local PE and the remote PE, respectively. The signaling notification mode is that negotiation consistency of pseudo wire freezing configuration is realized through signaling interaction between the local PE and the remote PE. For example: configuring a freezing attribute on a local PE or a far-end PE, sending the configured freezing attribute to a PE of an opposite end in a signaling notification mode, and configuring the PE of the opposite end according to the received freezing attribute; or, the local PE and the far-end PE configure the freezing attribute respectively, and send the configured freezing attribute to the PE of the opposite end in a signaling notification manner, and the local PE and the far-end PE negotiate the consistency of the configuration of the freezing attribute. The specific implementation operation will be described in detail in the following embodiments.

Step 202, when the local PE and the far-end PE are both configured with the freezing attribute of the pseudo wire, if the signaling session between the local PE and the far-end PE is interrupted or the protocol processors of the local PE and the far-end PE fail, the forwarding state of the pseudo wire is continuously maintained. The so-called signaling session includes all pseudowire-established sessions based on T-LDP and BGP.

The pseudowire of the invention is a broad pseudowire category, including single-hop pseudowires and multi-hop pseudowires. Local PE and far-end PE operational behaviors are also applicable to Switching provider edge nodes (S-PEs) of multi-hop pseudowires.

The following describes the processing method of the above pseudowire service in detail with reference to specific embodiments.

As shown in fig. 3, a flow for advertising a pseudowire frozen attribute through a T-LDP session according to an embodiment of the present invention includes the following steps:

step 301, the user configures a T-LDP session on the local PE to establish a T-LDP session with the remote PE for transmitting a signaling message of a pseudo wire.

Step 302, configuring a pseudo wire service on the local PE, including information such as a pseudo wire Identifier (ID), a pseudo wire type, and an ID of the far-end PE, and meanwhile configuring a frozen attribute of the pseudo wire. The steps and step 301 have no strict order relationship.

Step 303, judging whether the pseudo wire on the local PE is configured with the freezing attribute, if so, executing step 304; otherwise, step 310 is performed.

It should be noted that the local PE may configure the pseudowire freezing attribute after the pseudowire is successfully established, or may configure the pseudowire freezing attribute before the pseudowire is established.

In step 304, the local PE advertises the frozen attribute to the remote PE via a T-LDP session.

Step 305, judging whether the local PE receives the pseudo wire attribute notification of the far-end PE, wherein the pseudo wire attribute notification has a frozen attribute, if so, executing step 306; otherwise, step 310 is performed.

It should be noted that, the local PE does not receive the pseudowire attribute advertisement of the remote PE; or the local PE receives the pseudowire attribute advertisement of the remote PE but does not have the frozen attribute in the advertisement, step 310 is performed.

At step 306, the pseudowire freeze function is enabled.

After the pseudo wire freezing function takes effect, if the T-LDP session is interrupted or the protocol processors of the local PE and the far-end PE fail, the forwarding state of the pseudo wire is continuously maintained, wherein the forwarding state comprises a pseudo wire outgoing label received from the far-end PE and a locally distributed incoming label entry; meanwhile, the local PE continues to forward the customer service borne by the pseudo wire. If the PSN Tunnel carrying the pseudowire traffic is also interrupted at this time, the traffic will be interrupted.

Step 307, after the pseudowire with the frozen attribute is successfully established, the pseudowire state (PW Status, including information such as PW UP/DOWN) information transmitted through the T-LDP session is no longer transmitted by the T-LDP session. The pseudowire associated channel (PW associated channel) may be selected for transmission, or the pseudowire status information may be selected not to be transmitted.

At step 308, the customer may delete the frozen nature of the pseudowire, otherwise known as Unfreeze (Unfreeze), on the local PE, depending on the customer's needs. After the frozen attribute of the pseudo wire is deleted, if the T-LDP session is normal at the moment, the local PE needs to resend the LDP mapping message to the far-end PE according to the description of RFC4447, so that the far-end PE has the opposite-end information of the pseudo wire; if the T-LDP session has been interrupted at this point, the local PE needs to delete the forwarding information of the pseudowire and interrupt customer traffic.

In step 309, in the case that one of the local PE and the remote PE is restarted but the other is not restarted, the restart party will resend the updated pseudowire information (including the information in step 302). If the pseudowire information of the frozen pseudowire is updated from the T-LDP session, the pseudowire information needs to be updated so as to keep the pseudowire information to be up to date all the time. Service interruption may be caused during pseudowire information updating. After the pseudo wire is frozen, if the control board of the device has the main/standby protection function, the main control board needs to synchronize the forwarding information of the pseudo wire to the backup control board. If the device does not have the main/standby protection function, the device may store the forwarding information of the pseudo wire by other methods, such as storing in a Non-Volatile memory (Non-Volatile ROM). After the active/standby switching or the device is restarted, the T-LDP session is re-established, and if the pseudowire is found to be in the frozen state and the complete and correct forwarding information can be obtained, the pseudowire information still needs to be updated through the T-LDP session.

Step 310, when the local PE does not support the pseudowire freezing function, or receives the pseudowire attribute notification of the remote PE through the T-LDP session, and finds that the pseudowire does not have the freezing attribute, the local PE does not perform the related operations of freezing the pseudowire, but performs the operations according to the standard described in RFC 4447.

It should be noted that, after the pseudowire is thawed, the user can perform the freezing configuration of the pseudowire again, refer to the foregoing steps 302 to 307. The remote PE also needs to perform the same functional operations as the local PE (refer to steps 301 to 310), which is not described herein again.

As shown in fig. 4, a flow for advertising a pseudowire frozen attribute by static configuration according to an embodiment of the present invention includes the following steps:

step 401, the user configures a T-LDP session on the local PE to establish a T-LDP session with the remote PE for transmitting a signaling message of a pseudo wire.

Step 402, configuring pseudowire service on the local PE, including information such as pseudowire ID, pseudowire type, and ID of the far-end PE, and meanwhile configuring the frozen attribute of the pseudowire. The steps and step 401 have no strict order relationship.

Step 403, judging whether the pseudo wire on the local PE is configured with the freezing attribute, if so, executing step 404; otherwise, step 407 is executed.

At step 404, the pseudowire freezing function is enabled.

After the pseudowire freezing function is in effect, if the T-LDP session is interrupted or the protocol processors of the local PE and the far-end PE fail, the forwarding state of the pseudowire is continuously maintained, wherein the forwarding state comprises a pseudowire outgoing label received from the far-end PE and a locally distributed incoming label entry. Meanwhile, the local PE continues to forward the customer service borne by the pseudo wire. If the PSN Tunnel carrying the pseudowire traffic is also interrupted at this time, the traffic will be interrupted.

It should be noted that, the user needs to ensure through configuration, the local PE and the far-end PE configure the freezing attribute of the pseudo wire at the same time, otherwise, there will be service transmission at one end of the pseudo wire, and no service reception at the other end, resulting in network black hole phenomenon.

Step 405, after the pseudowire with the frozen attribute is successfully established, the pseudowire state (PW Status, including PW UP/DOWN and other information) information transmitted through the T-LDP session is not transmitted by the T-LDP session any more. The pseudowire associated channel (PW associated channel) may be selected for transmission, or the pseudowire status information may be selected not to be transmitted.

At step 406, the customer may delete the frozen nature of the pseudowire, otherwise known as Unfreeze (Unfreeze), on the local PE, depending on the customer's needs. After the frozen attribute of the pseudowire is deleted, if the T-LDP session is normal at this time, the local PE needs to resend the LDP mapping message to the remote PE as described in RFC4447, so that the remote PE has the peer-end information of the pseudowire. If the T-LDP session has been interrupted at this point, the local PE needs to delete the forwarding information of the pseudowire and interrupt customer traffic.

In step 407, if the local PE does not support the pseudowire freezing function, the local PE does not perform the freezing operation on the pseudowire, and performs the operation according to the standard described in RFC 4447.

It should be noted that, after the pseudowire is thawed, the user can perform the freezing configuration of the pseudowire again, refer to steps 402 to 405. The remote PE also needs to perform the same functional operations as the local PE (steps 401 to 407), which are not described herein again.

As shown in fig. 5, a flow of notifying a pseudowire freezing attribute to a far-end PE by a T-LDP session notification pseudowire freezing attribute through configuring the freezing attribute only in a single-sided PE according to an embodiment of the present invention includes the following steps:

step 501, a user configures a T-LDP session on a local PE to establish a T-LDP session with a remote PE for transmitting a signaling message of a pseudo wire.

Step 502, pseudowire service is configured on the local PE, including information such as pseudowire ID, pseudowire type, and ID of the far-end PE. This step and step 501 have no strict order relationship.

Step 503, only configuring the frozen attribute of the pseudowire on the local PE, and the local PE advertises this attribute to the remote PE through the T-LDP session. The far-end PE configures the freezing attribute of the far-end PE according to the received signaling session.

The local PE can configure the pseudowire freezing attribute after the pseudowire is successfully established, and can also configure the pseudowire freezing attribute before the pseudowire is established.

And step 504-505, the far-end PE sends a pseudo wire attribute notice to the local PE through the T-LDP session, and the pseudo wire freezing function takes effect.

Step 506, after the pseudowire with the frozen attribute is successfully established, the pseudowire state (PW Status, including PW UP/DOWN and other information) information transmitted through the T-LDP session is not transmitted by the T-LDP session any more. The pseudowire associated channel (PW associated channel) may be selected for transmission, or the pseudowire status information may be selected not to be transmitted.

At step 507, according to the requirement of the user, the user may delete the frozen attribute of the pseudowire, or Unfreeze, on the local PE. After the frozen attribute of the pseudowire is deleted, if the T-LDP session is normal at this time, the local PE needs to resend the LDP mapping message to the remote PE as described in RFC4447, so that the remote PE has the peer-end information of the pseudowire. If the T-LDP session has been interrupted at this point, the local PE needs to delete the forwarding information of the pseudowire and interrupt customer traffic.

In step 508, in the local PE and the remote PE, if one of the two parties is restarted but the other party is not restarted, the restart party will resend the updated PW information. And if the PW which is frozen is updated by receiving the PW information from the T-LDP session, the PW information needs to be updated so as to always keep the PW information to be the latest. During the PW information updating process, service interruption may be caused. After the pseudo wire is frozen, if the control board of the device has the main/standby protection function, the main control board needs to synchronize the forwarding information of the pseudo wire to the backup control board. If the device has no main/standby protection function, the device may store the forwarding information of the pseudo wire by other methods, such as storing in a Non-voice ROM. After the active/standby switching or the device is restarted, the T-LDP session is re-established, and if the pseudowire is found to be in the frozen state and the complete and correct forwarding information can be obtained, the pseudowire information still needs to be updated through the T-LDP session.

It should be noted that, after the pseudo wire is thawed, the user can perform the freezing configuration of the pseudo wire again, refer to steps 502 to 506. The above is explained by taking the local PE as an example, if the "single-side PE configuration freeze attribute" refers to the remote PE, the operation performed by the remote PE is similar to the operation performed by the local PE (steps 501 to 508), and the description thereof is omitted.

As further shown in fig. 6, it is a flow for notifying the VPLS freezing attribute by crossing a BGP signaling session according to the embodiment of the present invention, where the flow includes the following steps:

step 601, the user configures a BGP signaling session on the local PE to establish a BGP signaling session with the far-end edge router for transmitting the signaling message of the VPLS.

Step 602, configuring a VPLS service on the local PE, where the VPLS service includes information such as a Route Target (RT) of the VPLS, a Route Distinguisher (RD) of the VPLS, a Virtual Edge Identifier (VEID), and the like, and the VPLS freezing attribute needs to be configured. There is no strict order relationship between this step and step 601.

Step 603, judging whether the local PE is configured with the VPLS freezing attribute, if so, executing step 604; otherwise, step 609 is performed.

It should be noted that the local PE may configure the VPLS freezing attribute after the VPLS is successfully established, or may configure the VPLS freezing attribute before the VPLS is established.

In step 604, the local PE notifies the VPLS frozen attribute to the remote PE through a BGP signaling session.

Step 605, determining whether the local PE receives the VPLS attribute advertisement of the remote PE, and if so, executing step 606, where the pseudowire attribute advertisement has a frozen attribute; otherwise, step 609 is performed.

It should be noted that, the VPLS attribute advertisement of the remote PE is not received at the local PE; or the local PE receives the VPLS attribute advertisement of the remote PE, but the advertisement does not have the VPLS frozen attribute, step 609 is performed.

At step 606, a pseudowire freezing function is in effect, and this freezing function is only in effect for pseudowires between the two PEs.

After the pseudowire freezing function is in effect, if a BGP signaling session is interrupted or protocol processors of the local PE and the remote PE fail, the forwarding state between the two PEs will continue to be maintained, including the pseudowire outgoing label received from the remote PE and the pseudowire incoming label entry locally allocated. Meanwhile, the local/far-end PE continues to forward the customer service carried by the pseudo wire of the VPLS. If the PSNTunnel carrying the pseudowire traffic is also interrupted at this time, the traffic will be interrupted.

In step 607, the user can delete the frozen property of VPLS, or Unfreeze, on the local PE according to the user's needs. After the frozen attribute of the VPLS is deleted, if the BGP signaling session is normal at this time, the local PE resends the BGP update message according to the standard described in RFC 4761. If the BGP signaling session is interrupted, the local PE needs to delete the forwarding information of the pseudowire corresponding to the BGP signaling and interrupt the customer service carried by the pseudowire of the VPLS.

In step 608, in the local PE and the remote PE, if one of the two parties is restarted but the other party is not restarted, the restart party will resend the updated PW information. If the already frozen PW receives an update of the PW information from the BGP signaling session, the PW information needs to be updated, so as to keep the PW information up to date all the time. During the PW information updating process, service interruption may be caused. After the pseudo wire is frozen, if the control board of the device has the main/standby protection function, the main control board needs to synchronize the forwarding information of the pseudo wire to the backup control board. If the device has no main/standby protection function, the device may store the forwarding information of the pseudo wire by other methods, such as storing in a Non-voice ROM. After the active/standby switching or the device is restarted, the BGP signaling session is re-established, and if the pseudowire is found to be in the frozen state and complete and correct forwarding information can be obtained, the information of the pseudowire still needs to be updated through the BGP signaling session, so that the far-end PE has the opposite-end information of the pseudowire. Meanwhile, the routing of the PW by the VPLS needs to be selected according to the attribute of the BGP, and the freezing attribute is not included.

Step 609, if the local PE does not support the VPLS freezing function, or receives the VPLS attribute notification of the remote PE through the BGP signaling session, and finds that the VPLS does not have the freezing attribute, the local PE does not perform the freezing operation on the VPLS, but performs the operation according to the standard described in RFC 4761.

It should be noted that, after the pseudowire is thawed, the user can perform the freezing configuration of the pseudowire again, refer to steps 602 to 606. The remote PE needs to perform the same functional operations as the local PE (steps 601-609), which is not described herein again.

As shown in fig. 7, a flow for advertising a VPLS frozen attribute through static configuration in an embodiment of the present invention includes the following steps:

step 701, a user configures a BGP signaling session on a local PE to establish a BGP signaling session with a remote PE for transmitting a signaling message of a VPLS.

Step 702, configuring VPLS service on local PE, including information such as RT of VPLS, RD of VPLS, and VEID, and at the same time, configuring the VPLS freezing attribute. There is no strict order relationship between this step and step 701.

Step 703, judging whether the VPLS on the local PE configures the freezing attribute, if so, executing step 704; otherwise, step 706 is performed.

At step 704, the pseudowire freeze function is enabled. This freeze function can be for all pseudowires of this VPLS, or for a particular pseudowire between the VPLS and a far end PE.

After the pseudowire freezing function is in effect, if a BGP signaling session is interrupted or protocol processors of the local PE and the remote PE fail, a forwarding state between the two PEs will be continuously maintained, including a PW outgoing label received from the remote PE and a PW incoming label entry locally allocated. Meanwhile, the local/far-end PE continues to forward the customer service carried by the pseudo wire of the VPLS. If the PSNTunnel carrying the pseudowire traffic is also interrupted at this time, the traffic will be interrupted.

It should be noted that, a user needs to ensure through configuration, the local PE and the far-end PE configure the freezing attribute of the VPLS at the same time, otherwise, a service transmission is performed at one end of a pseudo wire between the two PEs, and no service is received at the other end of the pseudo wire, thereby forming a network black hole phenomenon.

Step 705, according to the user's requirement, the user can delete the frozen attribute of VPLS on the local PE, alternatively called unfreezing (Unfreeze). After the frozen attribute of the VPLS is deleted, if the BGP signaling session is normal at this time, the local PE still needs to update the information of the pseudowire through the BGP signaling session as described in RFC4761, so that the far-end PE has the opposite-end information of the pseudowire. If the BGP signaling session is interrupted, the local PE needs to delete the forwarding information of the pseudowire corresponding to the BGP signaling and interrupt the customer service carried by the pseudowire of the VPLS.

Step 706, if the local PE does not support the VPLS freezing function, the local PE does not perform the freezing operation on the VPLS, and performs the operation according to the standard described in RFC 4761.

It should be noted that, after the pseudo wire is thawed, the user can perform the freezing configuration of the pseudo wire again, refer to steps 702 to 704. The remote PE needs to perform the same functional operations as the local PE (steps 701-706), which is not described herein again.

As shown in fig. 8, a flow for a BGP session notification VPLS to notify a far-end PE of a pseudowire frozen attribute by configuring the frozen attribute only in a single-sided PE according to an embodiment of the present invention includes the following steps:

step 801, a user configures a BGP signaling session on a local PE to establish a BGP signaling session with a remote PE for transmitting a signaling message of a VPLS.

Step 802, VPLS service is configured on the local PE and the remote PE, including information such as RT of VPLS, RD of VPLS, and VEID. This step is not strictly sequential to step 801.

In step 803, the VPLS configures the frozen attribute only on the local PE, and the local PE notifies the attribute to the remote PE through the BGP signaling session. The far-end PE configures the freezing attribute of the far-end PE according to the received signaling session.

The local PE can configure the VPLS freezing attribute after the VPLS is successfully established, and can also configure the VPLS freezing attribute before the VPLS is established.

And 804-805, the far-end PE sends a VPLS attribute notification to the local PE through a BGP signaling session, and the pseudo wire freezing function takes effect. This freeze function only works for pseudowires between the two PEs.

At step 806, the user can delete the frozen property of VPLS on the local PE, otherwise called unfreezing (Unfreeze), according to the user's needs. After the frozen attribute of the VPLS is deleted, if the BGP signaling session is normal at this time, the local PE still needs to update the information of the pseudowire through the BGP signaling session as described in RFC4761, so that the far-end PE has the opposite-end information of the pseudowire. If the BGP signaling session is interrupted, the local PE needs to delete the forwarding information of the pseudowire corresponding to the BGP signaling and interrupt the customer service carried by the pseudowire of the VPLS.

In step 807, in the case where the local PE and the remote PE are restarted, if one of them is not restarted, the restart will resend the updated PW information. If the already frozen PW receives an update of the PW information from the BGP signaling session, the PW information needs to be updated, so as to keep the PW information up to date all the time. During the PW information updating process, service interruption may be caused. After the pseudo wire is frozen, if the control board of the device has the main/standby protection function, the main control board needs to synchronize the forwarding information of the pseudo wire to the backup control board. If the device has no main/standby protection function, the device may store the forwarding information of the pseudo wire by other methods, such as storing in a Non-voice ROM. After the active/standby switching or the device is restarted, the BGP signaling session is re-established, and if the pseudowire is found to be in the frozen state and complete and correct forwarding information can be obtained, the information of the pseudowire still needs to be updated through the BGP signaling session, so that the far-end PE has the opposite-end information of the pseudowire.

It should be noted that, after the pseudo wire is thawed, the user can perform the freezing configuration of the pseudo wire again, refer to steps 802 to 805. The above is explained by taking the local PE as an example, if the "single-side PE configuration freeze attribute" refers to the remote PE, the operation performed by the remote PE is similar to the operation performed by the local PE (steps 801 to 807), and is not described herein again.

Corresponding to the above pseudowire service processing method, the present invention also provides a pseudowire service processing device, which is applied to the local PE and the far-end PE, and the device comprises: a configuration module and a service processing module. And the configuration module is used for negotiating that the pseudo wire freezing configurations of the local PE and the far-end PE are consistent in a static configuration or signaling notification mode. And the service processing module is used for continuing to keep the forwarding state of the pseudo wire if the signaling session between the local PE and the far-end PE is interrupted when the local PE and the far-end PE are both configured with the freezing attribute of the pseudo wire.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.

Claims

1. A method for processing pseudo wire service is characterized in that the method comprises the following steps:

2. The method for processing the pseudo wire service according to claim 1, wherein the signaling session comprises: all pseudowire sessions are established based on the target label distribution protocol (T-LDP) and the Border Gateway Protocol (BGP).

3. The method of claim 1, wherein the protocol processors of the local PE and the remote PE have active/standby protection functions or function of storing pseudo wire information in a Non-Volatile memory (Non-Volatile ROM).

4. A method for handling pseudowire traffic according to claim 1, 2 or 3, characterized in that the method further comprises:

5. The method for processing the pseudo wire service according to claim 1, 2 or 3, wherein the pseudo wire freezing configuration is negotiated between the local PE and the remote PE in a signaling notification manner, specifically:

6. The method for processing the pseudo wire service according to claim 1, 2 or 3, wherein negotiating the consistency of the pseudo wire freezing configuration between the local PE and the far-end PE in a signaling notification manner specifically comprises:

7. The method for processing the pseudo-wire service according to claim 1, 2 or 3, wherein after the local PE and the far-end PE are both configured with the frozen attribute of the pseudo-wire, the method further comprises: and the local PE and the remote PE transmit the pseudo wire state information through a pseudo wire associated channel.

8. A processing device of pseudo wire service, which is applied in local PE and far-end PE, characterized in that the device comprises:

9. The apparatus for processing pseudowire traffic according to claim 7, wherein the signaling session comprises: all of the T-LDP and BGP based sessions for pseudowires are established.

10. The apparatus for processing pseudo-wire service according to claim 7, wherein the protocol processors of the local PE and the remote PE have a main/standby protection function or a function of storing pseudo-wire information in Non-voice ROM.

11. The apparatus for processing the pseudowire service according to claim 8, 9 or 10, wherein the configuration module is further configured to send a pseudowire attribute advertisement to an opposite end of the PE, and determine whether the opposite end is configured with the frozen attribute of the pseudowire by receiving the pseudowire attribute advertisement of the opposite end, thereby determining whether the frozen configurations of the pseudowires of the local PE and the far-end PE are consistent.

12. The apparatus for processing the pseudowire service according to claim 8, 9 or 10, wherein the configuration module is further configured to configure a frozen attribute of the pseudowire, notify the frozen attribute to an opposite end of the PE through a signaling session, and receive a pseudowire attribute notification sent by the opposite end.

13. The apparatus for processing the pseudowire service according to claim 8, 9 or 10, wherein the configuration module is further configured to configure a freezing attribute on the local PE or the far-end PE, send the configured freezing attribute to the PE of the opposite end in a signaling notification manner, and trigger the PE of the opposite end to perform configuration according to the received freezing attribute;

14. The apparatus for processing pseudowire service according to claim 8, 9 or 10, wherein the service processing module is further configured to transmit pseudowire status information between the local PE and the far-end PE through the pseudowire association channel after the local PE and the far-end PE are both configured with the frozen attribute of the pseudowire.