[c-nsp] Devil's Advocate - Segment Routing, Why?

Mark Tinka mark.tinka at seacom.mu
Fri Jun 19 08:35:07 UTC 2020

On 19/Jun/20 10:18, Saku Ytti wrote:

> I need to give a little bit of credit to DC people. If your world is
> compute and you are looking out to networks. MPLS _is hard_, it's
> _harder_ to generate MPLS packets in Linux than arbitrarily complex IP
> stack. Now instead of fixing that on the OS stack, to have a great
> ecosystem on software to deal with MPLS, which is easy to fix, we are
> fixing that in silicon, which is hard and expensive to fix.
> So instead of making it easy for software to generate MPLS packets. We
> are making it easy for hardware teo generate complex IP packets.
> Bizarre, but somewhat rational if you start from compute looking out
> to networks, instead of starting from networks.

Which I totally appreciate and, fundamentally, have nothing against.

My concern is when we, service providers, start to get affected because
equipment manufacturers need to follow the data centre money hard, often
at our expense. This is not only in the IP world, but also in the
Transport world, where service providers are having to buy DWDM gear
formatted for DCI. Yes, it does work, but it's not without its

Cycling, over the past decade, between TRILL, OTV, SPB, FabricPath,
VXLAN, NV-GRE, ACI... and perhaps even EVPN, there is probably a lesson
to be learned.


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