Re: IS-IS Flat Network Size
Andrey Kostin via NANOG <[email protected]>
| Newsgroups | gmane.org.operators.nanog |
|---|---|
| Message-ID | <[email protected]> |
Mark Tinka via NANOG писал(а) 2026-08-02 07:43: > On 02/08/2026 13:21, Saku Ytti wrote: > >> 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. > > Yes, large networks with Metro-E rings can either have a flat L2 domain > that communicates between the core and metro, or can have BGP-LU > separating them (as you say, the Seamless MPLS definition). > > I suppose in either case, a single L2 domain remains as the only scope, > whether separated by BGP-LU or not. > > I have ran both topologies without issue, but admittedly, different > scales. > > Mark. With SR-ISIS you don't need BGP-LU, although still need L2 to L1 leaking. But when loopbacks from L2 become available in L1, ISIS advertises them with [binding] labels, so Seamless MPLS comes much easier. Kind regards, Andrey _______________________________________________ NANOG mailing list https://lists.nanog.org/archives/list/[email protected]/message/YG2PSWGIXDZYIE6HJPU4VMOYHVUGGM6S/