Devil's Advocate - Segment Routing, Why?

James Bensley jwbensley+nanog at
Tue Jun 30 18:43:20 UTC 2020

On Wed, 17 Jun 2020 at 23:19, Mark Tinka <mark.tinka at> wrote:
> Yes, we all love less state, I won't argue that. But it's the same question that is being asked less and less with each passing year - what scales better in 2020, OSPF or IS-IS. That is becoming less relevant as control planes keep getting faster and cheaper.
> I'm not saying that if you are dealing with 100,000 T-LDP sessions you should not consider SR, but if you're not, and SR still requires a bit more development (never mind deployment experience), what's wrong with having LDPv6? If it makes near-as-no-difference to your control plane in 2020 or 2030 as to whether your 10,000-node network is running LDP or SR, why not have the choice?

I'm going to kick the nest in the other direction now :D ... There
would be no need to massively scale an IGP or worry about running
LDPv4 + LDv6 or SR MPLS if we had put more development time into MPLS
over UDP. I think it's a great technology which solves a lot of
problems and I've been itching to deploy it for ages now, but vendor
support for it is nowhere near the level of MPLS over Ethernet.


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