MPLS Pseudowire Status Signaling
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MPLS Pseudowire Status SignalingLast Updated: January 12, 2012
The MPLS Pseudowire Status Signaling feature enables you to configure the router so it can send pseudowire status to a peer router, even when the attachment circuit is down. In releases prior to Cisco IOS 12.2(33)SRC, if the attachment circuit was down, the pseudowire status messages were not sent to the peer.
Finding Feature InformationYour software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required. Prerequisites for MPLS Pseudowire Status Signaling
Restrictions for MPLS Pseudowire Status Signaling
Information About MPLS Pseudowire Status SignalingHow MPLS Pseudowire Status Signaling WorksIn releases prior to Cisco IOS Release 12.2(33)SRC, the control plane for AToM does not have the ability to provide pseudowire status. Therefore, when an attachment circuit (AC) associated with a pseudowire is down (or is forced down as part of the Pseudowire Redundancy functionality), labels advertised to peers are withdrawn. In Cisco IOS Release 12.2(33)SRC, the MPLS Pseudowire Status Signaling feature enables the AC status to be sent to the peer through the Label Distribution Protocol. The pseudowire status messages are sent in label advertisement and label notification messages if the peer also supports the MPLS Pseudowire Status Signaling feature. You can issue the show mpls l2transport vc detail command to show that both the local and remote routers support pseudowire status messages. The following example shows the line of output to look for:
Router# show mpls l2transport vc detail
. . . status TLV support (local/remote): enabled/supported
When One Router Does Not Support MPLS Pseudowire Status SignalingThe peer routers must support the ability to send and receive pseudowire status messages in label advertisement and label notification messages. If one router does not support pseudowire status messages, Cisco recommends that you disable the messages with the no status command. This returns the router to label withdraw mode. If the peer does not support the MPLS Pseudowire Status Signaling feature, the local router changes its mode of operation to label withdraw mode. You can issue the show mpls l2transport vc detail command to show that the remote router does not support pseudowire status messages. The following example shows the line of output to look for:
Router# show mpls l2transport vc detail
. . . status TLV support (local/remote): enabled/not supported When you issue the following debug mpls l2transport vccommands, the messages show that the peer router does not supportthe MPLS Pseudowire Status Signaling feature and that the local router is changing to withdraw mode, as shown in bold in the following example: Router# debug mpls l2transport vc event Router# debug mpls l2transport vc status event Router# debug mpls l2transport vc status fsm Router# debug mpls l2transport vc ldp *Feb 26 13:41:40.707: AToM LDP [110.1.1.2]: Sending label withdraw msg *Feb 26 13:41:40.707: AToM LDP [110.1.1.2]: VC Type 5, mtu 1500 *Feb 26 13:41:40.707: AToM LDP [110.1.1.2]: VC ID 100, label 18 *Feb 26 13:41:40.707: AToM LDP [110.1.1.2]: Status 0x0000000A [PW Status NOT supported] Status Messages Indicating That the Attachment Circuit Is DownWhen the attachment circuit is down between the two routers, the output of the show mpls l2transport vc detail command shows the following status:
Router# show mpls l2transport vc detail
. . . Last remote LDP TLV status rcvd: AC DOWN(rx,tx faults) The debug messages also indicate that the attachment circuit is down, as shown in bold in the command output: Router# debug mpls l2transport vc event Router# debug mpls l2transport vc status event Router# debug mpls l2transport vc status fsm Router# debug mpls l2transport vc ldp
*Feb 26 11:51:42.427: AToM LDP [10.1.1.1]: Received notif msg, id 88
*Feb 26 11:51:42.427: AToM LDP [10.1.1.1]: Status 0x00000007 [PW Status]
*Feb 26 11:51:42.427: AToM LDP [10.1.1.1]: PW Status 0x00000006 [AC DOWN(rx,tx faults)]
Other pseudowire status messages include not-forwarding, pw-tx-fault, and pw-rx-fault. Message Codes in the Pseudowire Status MessagesThe debug mpls l2transport vcand the show mpls l2transport vc detail commands show output that contains message codes. For example: Label/status state machine: established, LruRru AToM MGR [10.9.9.9, 100]: S:Evt local up, LndRru->LnuRru The message codes (LruRru, LndRru, and LnuRru) indicate the status of the local and remote routers. You can use the following key to interpret the message codes: L--local router R--remote router r or n--ready (r) or not ready (n) u or d--up (u) or down (d) status The output also includes other values: D--Dataplane S--Local shutdown How to Configure MPLS Pseudowire Status SignalingEnabling MPLS Pseudowire Status SignalingPerform the following task to enable the router to send pseudowire status to a peer router even when the attachment circuit is down. If both routers do not support pseudowire status messages, then disable the messages with the no status command. DETAILED STEPS Configuration Examples for MPLS Pseudowire Status Signaling
MPLS Pseudowire Status Signaling ExampleThe following example configures the MPLS Pseudowire Status Signaling feature on two PE routers. By default, status messages are enabled. The status command is included in this example in case status messages have been disabled. Verifying That Both Routers Support Pseudowire Status Messages ExampleYou can issue the show mpls l2transport vc detail command to show that both the local and remote routers support pseudowire status messages. The following example shows the line of output to look for:
Router# show mpls l2transport vc detail
. . . status TLV support (local/remote): enabled/supported Additional ReferencesRelated Documents
MIBsTechnical Assistance
Feature Information for MPLS Pseudowire Status SignalingThe following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R) Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental. © 2012 Cisco Systems, Inc. All rights reserved.
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