Vikas,
The result was that C 'knew' via the BGP session with A, that to
get to external network 'ext-net', it should send traffic to A. It does
the IGRP lookup to get to A, and sends the traffic to 'B'. However,
since B did not have a BGP session with A, it did not know how to get
to the ext-net (in the real case, B was sending traffic back to C since
the default route was via C).
This is a documented limitation running with "no synchronization".
What really make me worried is that there doesn't seem to be way
to detect this kind of a problem easily.. how do others monitor
their BGP sessions ?
"show ip bgp summary".
And a little bird tells me that there is MIB in the works...
Tony