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Cisco Bug: CSCtd63806 - L2-L2VPN_PW-3-UPDOWN state changes on backup pseudowire

Last Modified

Jan 15, 2017

Products (4)

  • Cisco Carrier Routing System
  • Cisco IOS XR Software
  • Cisco ASR 9010 Router
  • Cisco ASR 9006 Router

Known Affected Releases

3.7.3.MPLS

Description (partial)

Symptom:
When you configure MPLS l2vpn redundant pseudowires you may see the backup pseudowire briefly report changing state to up and then back down very quickly.

RP/0/RSP0/CPU0:Dec  4 14:10:38.009 MET-1MEST,M3.5.: l2vpn_mgr[259]: %L2-L2VPN_PW-3-UPDOWN : Pseudowire with address 10.10.10.20, id  901001, state is Up 
RP/0/RSP0/CPU0:Dec  4 14:10:38.009 MET-1MEST,M3.5.: l2vpn_mgr[259]: %L2-L2VPN_PW-3-UPDOWN : Pseudowire with address 10.10.10.20, id  901001, state is Down 

If the label switch path (LSP) for the backup pseudowire that is down changes, it triggers a pseudowire up and then down event and syslog message on the far end.

This happens because l2vpn_mgr sends label mapping message for the backup pseudowire to the far end. Then l2vpn_mgr realizes that it's a backup pseudowire, and the primary is already UP, so l2vpn_mgr sends label withdrawal to far end.
 
On receiving the label mapping message from the far end l2vpn_mgr brings up the backup pseudowire. On receiving the label withdrawal message, it brings down the backup pseudowire. That's the reason we see Up/Down messages on the console.

This bug is to try change the behavior so that the event does not produce a syslog up and then down flap event.

Conditions: This problem was reported in IOS-XR release 3.7.3 on an ASR9000 but applies to all releases and platforms.
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