on 16.12.2011 19:49 Ondrej Zajicek wrote: > On Fri, Dec 16, 2011 at 02:14:48PM +0100, Stefan Jakob wrote: >> Dear Bird Users, >> >> I have the following setup: >> >> Peer1 - AS65001 >> Peer2 - AS65002 >> >> RS - AS65123 >> GW - AS65123 >> >> >> All are connected via a layer 2 infrastructure and share next hop >> addresses out of a /22. This /22 is part of a /20. >> >> RS works as a routeserver with "rs client" in the protocol definition of >> Peer1, Peer2. >> >> My goal is, to announce the /20 over GW to the routeservers GW hasn't >> the "rs client" option set but "gateway direct". >> >> To solve the iBGP and empty AS path of GW, I want to prepend AS65123 for >> all GW incoming prefixes, so that the as path isn't empty. >> >> Do you expect this as a working design to announce the /20 from GW via >> RS to the peers? > > This is a bit tricky. I see a possible problem - received route on RS > would be probably rejected as loopy (received AS PATH contains local ASN) >
Well, RS would prepend AS65123 towards Peer1 and Peer2, not GW toward RS. This is intended iBGP behaviour, isn't it. > I see a simpler idea - just use a different 'local as' (perhaps some > private ASN) on the BGP config on RS directed to GW (i.e. just on that one > connection). In that case the session would be handled as eBGP, like all > other sessions. Because the session would be also configured with 'rs > client' on RS, the configured (private) ASN would not appear anywhere, > it does not matter. > Well, is that really simpler? > BTW, why not just announce that /20 directly on RS? I think that should > work too (this is probably not documented, but locally originated routes > receives ASN to their path even when propagated through the session with > 'rs client' enabled. > That also would need additional config as yyou would have to set next-hop to GW (actually the whole truth is that there are two GW) Wouldn't the original proposal (% the update I gave) reflect standard behaviour? Arnold -- Arnold Nipper / nIPper consulting, Sandhausen, Germany email: [email protected] phone: +49 6224 5593407 2 mobile: +49 152 53717690 fax: +49 6224 5593407 9
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