Devil's Advocate - Segment Routing, Why?

Mark Tinka mark.tinka at
Thu Jun 18 08:42:11 UTC 2020

On 18/Jun/20 09:30, Saku Ytti wrote:

> Yes work left to be done. Ultimately the root problem is, no one cares
> about IPv6. But perhaps work with vendors in parallel to LDPv6 to get
> them to fix OSPFv3 and/or ISIS.

Yes, this.

Vendor feedback for those not supporting LDPv6 is that there is no
demand for it. And like I said in the previous thread, LDPv6 demand is
not about LDPv6, it's about IPv6.

If the majority of the high-paying vendors' favorite customers that pay
for CGN's continue to do so, what incentive do they have to ask for
IPv6. The T-Mobile US's of the world are few and far between, sadly.

I suppose I would not be unwilling to push the vendors to support
SR-OSPFv3 and SR-ISISv6 as I am also pushing them to support LDPv6 where
it is lacking, because at some point in the future, I do want to deploy
SR-MPLS in the same way I envisioned doing so back in 2014. I just need
to take it on a few dates first before I bring it home to meet the folks

> FWIW I am definitely saying that, and it should be IGP+BGP. I do
> accept and realise a lot of platforms only did and do Martini not
> Kompella, so reality isn't quite there.

That was me in 2013/2014. Dump LDP, dump RSVP, get SR deployed, forward
IPv4 natively in MPLSv4, and IPv6 natively in MPLSv6. But life happened.

Nonetheless, I will go SR-MPLS in many years to come, after I'm feeling
comfortable about it. That's a promise. But until then, I'd like
trusted, stable IPv4-IPv6 MPLS forwarding parity.

I have never cared much for VPLS because I thought it was a very messy
piece of tech. from Day 1. And while EVPN makes more sense, for our
market, more than 98% of the traffic we sell is IP-based, so we have no
demand for mp2mp Ethernet VPN's. But for those that adore VPLS (or
EVPN), let them have the choice of LDP or BGP, which both Cisco and
Juniper, after years of muscle-flexing, both ended up agreeing on
anyway, despite all the fuss.

So the LDPv6 vs. SR-MPLS vs. SRv6 vs. SRv6+ posturing is a rehash of
those LDP vs. BGP days, which just wastes everyone's time.


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