[c-nsp] BGP Default announcement disappearing

[Phil Rosenthal]

Hi all,

I know we've seen this bug now for several years, and I've given up  
hope for cisco ever fixing it.

We're now running SRD on a Sup720.

For those of you who haven't seen the bug before, it goes something  
like this:

1) Everything is working fine, you have your router in a full mesh in  
your network, seeing several full tables from various sources,  
including (at least) one directly connected full transit provider  
announcing a full table (or at least some peer with a very large  
number of routes).  You are announcing default (0.0.0.0/0) to several  
customer peers via BGP.
2) Transit provider (or peer with large number of routes) flaps a  
couple of times in rapid succession
3) A small number of default-only customer peers will see the default  
route get withdrawn, but most will continue as normal
4) Any default-only customer peer that flaps after this point will  
either not learn the default route, or will see it announced and then  
withdrawn immediately afterwards.

Sessions that are like this (supposed to be receiving default, but  
not), still show up just fine in a show ip bgp nei x.x.x routes  
command, eg:
BGP table version is 20510920, local router ID is x.x.x.x
Status codes: s suppressed, d damped, h history, * valid, > best, i -  
internal,
               r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

Originating default network 0.0.0.0

    Network          Next Hop            Metric LocPrf Weight Path

Total number of prefixes 0


Does anyone know of a way to get the router to once again announce  
0.0.0.0/0 without a reload?
I've tried removing the null0 route for 0/0 and re-adding it, as well  
as completely unconfiguring the sessions that should learn default and  
re-adding them, neither has worked.

Thanks,
-Phil