The MPLS WG Archive

[Curtis Villamizar <curtis@workhorse.fictitious.org>]

In message <39D2E493.DD05F9C3@idecnet.com>, Michel Redondo Ferrero writes:
> Hi,
> 
> Considering the next scenario:
> 
> -Core and Border routers running IS-IS, MPLS
> -VPNs configured in Border routers using BGP/MPLS
> -Border routers running BGP with full-routing
> 
> The question:
> Do Core routers need to run BGP? Is IS-IS enough?
> 
> Thanks in advance for your answers.
> 
> Michel Redondo Ferrero


Core routers do not need to run IBGP as long as all external traffic
through them goes through MPLS tunnels.  If there is a full mesh of
MPLS tunnels among routers with EBGP peers then this is the case.  The
only routers that must run IBGP are those that have EBGP peers.  In
rfc2547 speak these are the PE routers.

For example, optical switches will definitely NOT run IBGP with the
Internet routers.  They run an IGP and MPLS (plus LMP) but not BGP.
(In any reasonably sane network).

Curtis