A quick clarification -- the liberal BGP widthraw policy implemented by Cisco
(and a few other vendors) only accounts for a small fraction of the ~5 million
plus daily withdraws in the default-free Internet. The real source of all
these spurious withdraws remains a bit of a mystery. Our data shows some
strange sort of 30 second looping/oscilation behavior is taking place.
Possible causes of this behavior include configuration errors, unexpected
IGP-EGP interactions, vendor implementation bugs, and problems inherent with
the BGP protocol itself.The source of the millions of BGP withdraws is NOT Cisco's "liberal BGP
withdraw" policy -- this generates a fairly minor number of extra withdraws
(O(n) per router), and there are a quite a few valid and compelling reasons
for wanting implementing BGP this way.- Craig
What %age of the route assertions and withdrawls are substantially the same
set of routes each day?
Avi