[25121] in North American Network Operators' Group
Re: IS-IS reference
daemon@ATHENA.MIT.EDU (Vijay Gill)
Wed Sep 15 15:10:13 1999
Date: Tue, 14 Sep 1999 15:28:32 -0400 (EDT)
From: Vijay Gill <wrath@cs.umbc.edu>
To: nanog@merit.edu
In-Reply-To: <19990914115855.A14951@globalcenter.net>
Errors-To: owner-nanog-outgoing@merit.edu
On Tue, 14 Sep 1999, Dave Cooper wrote:
> 1. if you are going to scale a large national backbone, limit as much
> as you can in your IGP. the less fluctation in flooding protocols, the
> better. and since most backbones run on a single area (on the main
> IGP process) or level-2 only, then fluctuations cause headaches for
> all participating routers. this is especially so when you have a
> full layer-2 mesh or a full MPLS mesh.
A full mpls mesh should not be a problem as instantiated LSP's are
probably not going to be in your igp. Running an IGP over an (opaque) LSP
adds a lot to your complexity without delivering any major benefits.
You can add hierarchy to your topology obviating a need for a full mesh at
the L2 level.
Hierarchy can solve almost any scaling issue. Hierarchy in BGP through
confederations/RR, hierarchy in your IGP and hierarchy in your physical
circuit layout.
/vijay
