Hold on. I think I'm going to answer my own question. BGP only advertises the best route to peers. Looking at my eBGP peer in AS 200 says it's best route is via AS 300, it DOES have both paths in it's BGP table.
Theory proved - I removed the AS PATH Prepending and I can see all paths on my iBGP peer in AS 200. Happy days. On Fri, Feb 17, 2012 at 9:58 PM, Bal Birdy <[email protected]> wrote: > Hey All, > > So im currently playing with BGP and have come across something odd. I > have a three AS config so AS 200 connected to AS 400 and 300, and AS 400 > and 300 connected together i.e. a circle. Now I have a NLRI of 11.11.11.11 > in AS 400 that I'm advertising out, I want AS 200 to connect via AS 300. So > to achieve this I'm using AS Path Prepending. So far so good. Now what I'm > finding is that my eBGP router between 200 and 400 see's the NLRI with > correct path but it's iBGP peer is not. Now what I mean here is that my > iBGP peer doesnt even have it listed in the BGP table, it only has the NLRI > as advertised from AS 300. > > Now when I debug my update messages I can see the NLRI being advertised > from the AS 200 ebGP router, but then I get a withdrawn message straight > away. Can someone explain this? > In addition, if I shutdown the path from AS 200 to AS 300 the NLRI stays. > The minute I re-enable that path I get the withdrawn message. > > The only thing I can think is that route via AS 300, though a shorter path > is also an eBGP route and becuase of the AD being lower it's listed in my > route table BUT i'd still expect to see all paths in my BGP table. > > What am I missing?? > > Thanks > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
