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Cisco Bug: CSCtf23727 - BGP must not register with route watch while RP is standby

Last Modified

Mar 01, 2018

Products (1)

  • Cisco IOS

Known Affected Releases

12.2SRE 12.2XN 12.4T

Description (partial)

On a dual-RP PE router where a BGP CE peer is connected via a PPP link and the CE peer is also configured for NSR ("neighbor ha-mode sso" command), forwarding for prefixes learned from the CE router may fail after an RP switchover. After the switchover, the affected routes appear in the BGP table without a bestpath and the reason "nexthop inaccessible" listed.

The problem can be seen when all of the following conditions are true:
* The PE router is dual-RP
* The PE router is configured for SSO redundancy mode and is operating in hot standby mode
* The PE is connected to a CE router over an PPP link
* On the PE router, the CE neighbor is configured for BGP NSR
* BGP learns prefixes from the CE and the nexthop addresss for those prefixes are via PPP
* An RP switchover is performed
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