Re: IS-IS Flat Network Size

[Saku Ytti via NANOG <nanog () lists nanog org>]

On Sun, 2 Aug 2026 at 12:31, Mark Tinka <mark@tinka.africa> wrote:

> An obvious case against multi-level IS-IS is that to create end-to-end
> MPLS LSP's, you need each node to have every other node in its LFIB.

I think 'end-to-end' here can be defined in many ways. But I would
consider seamless MPLS as end-to-end, and of course in this case you
have no global IGP, you have metros having their own level2, and core
having its own level2, none of them communicate.
I've done that as well, and that's generally the approach if you
cannot justify global L2, there is no real case for L1, L1L2, L2
design.


-- 
  ++ytti
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