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Cisco Bug: CSCvh87605 - "Negative Path counter" traceback for BGP neighbor printed.

Last Modified

Jan 14, 2020

Products (1)

  • Cisco Carrier Routing System

Known Affected Releases

6.3.3.BASE 6.4.1.BASE 6.4.2.ADMIN 6.4.2.BASE 6.5.1.BASE 6.5.2.BASE 6.5.2.ROUT

Description (partial)


Negative Path count traceback gets printed from standby bgp.
After this it has functional impact post fail-over.

NSR enabled in bgp.

Issue may happen if following events occur:
1) on standby bgp, neighbor n1 gets reset just after TCP init sync.
2) bgp init sync gets completed and becomes NSR ready.
3) on active bgp, neighbor n1 flaps before scoped sync is started.

Once n1 comes up and starts learning prefixes, issue can be seen on standby.

Many NSR related events need to happen in specific order for issue to happen.
It is very heavily based on timing condition. No easy steps to reproduce it.
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