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Cisco Bug: CSCtd05282 - Saw %ROUTING-BGP-3-NEGCOUNTER msg during route flap

Last Modified

May 16, 2018

Products (1)

  • Cisco Carrier Routing System

Known Affected Releases

3.8.0.ROUT 3.8.2.ROUT 3.8.3.ROUT 4.0.0.BASE

Description (partial)


During route flapping, the number of bestpaths under neighbor address family is   
updated incorrectly.


The reproted problem occurs when (a) UUT has learned a prefix from two peers, 
(b) UUT selected path #1 as bestpath over path #2 and imported it into local 
same-rd table, and (c) the peer who sent path #1 sends an implicit withdrawal 
where the new path is not preferred over path #2.
When BGP receives the new path (implicit withdrawl), BGP ends up skipping to 
update (i.e. decrement) the bestpath counter. 
Similarly, when the peer who sent path #1 sends another implicit
withdrawl with prefered path over path #2, BGP skips to update (i.e.
increment) the bestpath counter.
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  • Status
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