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Re: Sprint BGP filters in 207.x.x.x?
In message <199512140726.BAA08568@freeside.fc.net>, Jeremy Porter writes: > >>If we had a good method for people to indicate routes that they didn't want > to > >>be aggregated, then more proxy aggregation could be done safely. > >> > > > > If I may... The idea of using a routing registry for > > this purpose has been suggested before. I still think > > it is a valid approach. Could be very useful in assisting > > with better proxy aggregation for all. > > Let me just say I think the RR has some good uses, i.e. > finding out what people intended the routing to look like, etc. > > I don't really understand how a RR can help with proxy aggregation > seeing as the route objects really only provide origin AS > and regular aggregation. The additional clues can be found in the aut-num for dual homed AS. If a route is registered with more than one origin AS and you route differently to these two AS, that's a clue to look carefully before proxying too. > It seems to me dual homed sites which are the concence of > proxy aggregation, can be detected with a reasonably full set > of routes, i.e. the second from AS from the origin in the ASPATH > being different. (Or some split in the path outside of an > AS communinity or confederation). The secondary route may not be advertised to you if the primary suppresses the advertisement. For example if previders are A and B and they peer with each other, I may think I can aggregate some prefix over provider A, but B may not be advertising a backup path since it is preferring the same primary through A. Curtis