[c-nsp] iBGP confed question

Tim Durack tdurack at gmail.com
Wed Jan 9 11:07:15 EST 2008


On Jan 9, 2008 10:56 AM, Pete Templin <petelists at templin.org> wrote:
> Tim Durack wrote:
>
> > We run iBGP confeds between 3 POPs (seems more natural than
> > route-relectors), redundant routers at every POP, topology is
> > essentially a big ring over L2 transport.
> >
> > iBGP sessions are between IGP loopbacks. (I always thought iBGP should
> > be between loopbacks, rather than interface addresses, that way
> > sessions survive link failures without effect.)
>
> It's been 2-3 years since I abandoned confederations for route
> reflectors, and this is the first I've "looked back".  I can't remember
> specifically, but I think you might want to consider the ieBGP sessions
> (between the sub-ASen) on interface addresses, to allow the (sub) AS
> path to guide path selection in the event of WAN link failures.

That's what I had been thinking.

> > Is this correct, or is there an argument for iBGP between interface
> > addresses, making BGP more "aware" of the underlying topology? Maybe
> > it's a stupid question, but I haven't come up with a good answer
> > yet...
>
> FWIW, I switched from confederations to full mesh to route reflectors as
> we grew from four Riverstone routers to ~25 Cisco routers.  Our network
> was much happier as a result.  :)  Feel free to ping me offline if
> there's any guidance I can provide.

We are still small, so I would be interested to know why you went the
confed -> rr path.

We're not slinging full tables around, just our own global prefixes,
and default from different providers. In the future we will likely be
doing some L2/L3 MPLS VPN stuff, advertised through BGP.

Thanks,

Tim:>


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