[nsp] BGP route withdrawal bug?

[Pete Templin]

sam_ml at spacething.org wrote:

> Was wondering if anyone had ever seen a C6500 (Sup2/MFSC2) behave like 
> this before. First warning we had was when all of a sudden, without 
> warning, the amount of routes it was advertising via iBGP dropped 
> dramically.
> 
> Looked at the router in question and it appeared to not be having any
> problems. However, when I did a 'sh ip bgp nei x.x.x.x routes' on a full
> transit feed it only showed ~500 prefixes, but 'sh ip bgp sum | inc
> x.x.x.x' implied it was still receiving a full table (~138,000 routes)

One of my upstreams had a similar problem.  I was migrating from a DS3 
homed into a GSR at their POP to a Metro Ethernet homed into a C6500. 
When I flipped MED values to make the Metro Ethernet the preferred link, 
MLS didn't release some of my routes (or it may have been down to the 
/32 FIB level; I don't remember), and I saw Roto-Router on traceroutes. 
Two of their core engineering folks immediately recognized the issue, 
acknowledged a known Cisco bug, and scheduled a software update for two 
days later.  Poof!  All better.

Unfortunately, I don't know what versions were implicated in the event.

pt