Announce less specific prefix in routeserver environment for upstream purpose

[Ondrej Zajicek]

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 at 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."
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