On Fri, Dec 16, 2011 at 11:39:38PM +0100, Arnold Nipper wrote:
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.
In that case it is probably OK.
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?
It depends. This variant does not need any special handling in filters.
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?
With the update it probably is. -- Elen sila lumenn' omentielvo Ondrej 'SanTiago' Zajicek (email: santiago@crfreenet.org) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so."