IBGP Question --- Router Reflector or iBGP Mesh

Alexei Roudnev alex at relcom.net
Wed Jan 12 08:06:19 UTC 2005

Are you sure? RR should just distribute routes.

RR do not make any route decisions, and (btw) iBGP do not make route
decisions - they are mostly based on IGP routing. All iBGP + RR are doing
- tie external routes to internal IP;
- distribute this information using iBGP mesh, RR's etc.
- receive this information and set up routing using internal IP (which are
routed by IGP protocls).

End routers receives iBGP routes and uses IGP (OSPF or EIGRP or anything you
use) for route decisions (of course, we can image exceptions, but normally ,
it works so that all decisions are based on IGP routing). Most important
decisions are done , where routes are emitted from EBGP into iBGP, others -
by iGP; which decisions are done by RR's themself?

> On Tue, 2005-01-11 at 13:09, Daniel Roesen wrote:
> > One of the main problems of route reflection is that the best path
> > decision is done centrally. The best route is not seen as from the
> > router making the forwarding decision, but from the route reflector's
> > point of view. Depending on network topology, geographic spread end
> > peering/transit topo, this might/will have significant negative effects.
> This is where good use of clusters and logical network design are
> necessary, but I don't think this is a route-reflector specific problem,
> more a general networking problem once your network starts groing and
> you start deploying a more complex edge/core based topology. I don't
> think this is a reason to not use reflection as oppossed to full mesh.
> Cheers,
> -- 
> ---
> Erik Haagsman
> Network Architect
> We Dare BV
> tel: +31(0)10 7507008
> fax:+31(0)10 7507005
> http://www.we-dare.nl

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