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

Mark Tinka mark.tinka at seacom.mu
Fri Jun 19 11:26:43 UTC 2020

On 19/Jun/20 13:11, Saku Ytti wrote:

> ASR9k also has low and high scale cards, we buy the low scale, even
> for edge. But even low scale is pretty high scale in this context.

You're probably referring to the TR vs. SE line cards, yes?

We would also buy TR line cards for high-touch use-cases, because, as
you say, that is pretty high scale as well, already :-).

I think the SE line cards are meant for high-capacity BNG terminations
in a single chassis, per line card. But with most IP traffic a network
is carrying being best-effort and capacity available all over the place,
what's the point anymore?

> I think there would be market for on-chip only LSR/core cards.
> Ultimately if you design for that day1, it won't add lot of costs to
> you. Yes the BOM difference may not be that great, because ultimately
> silicon is cheap and costs are in NRE. But the on-chip only cards
> would have bit more ports and they'd have better availability due to
> less component failures.
> I would fight very hard for us buy such cards in core, if vendor would
> offer them.

Same here.

For now, we are exploring the PTX1000/10002 machinery. I know fixed form
factor boxes for a core are a bit strange, but looking at how far the
tech has come, I'm feeling a lot more bullish about having a core box
that isn't redundant in control planes, data planes, and all the rest.
Just power supplies :-).

A lot of money to be saved if the idea works.

> Like the trio-in-pci full open, I think this is just marketing
> failure. Vendors are wearing their DC glasses and don't see anything
> else. While the big-name DC are lost cause, AMZN employs more chip
> designers than JNPR, matter of time before JNPR loses amzn edge too to
> internal amzn product.
> Someone with bit bolder vision on what the market could be, may have
> real opportunity here.

This is what I've been telling the vendors since about 2017, both IP and
Transport. It's only a matter of time before the level of development
happening in the cloud + content houses far surpasses what the vendors
are doing, if not already. Why spend all your time, energy and resources
on a market that isn't going to find use for your NRE, and can probably
out-code  and out-research you with one hand tied behind their back, any

The only reason they aren't building their own core routers yet is
because that's an area where they can still afford to offload
development time to the vendors. The edge is where they need to badly
optimize, and they will do it a lot more efficiently than the vendors
can, in time, if not already.

When I saw one cloud provider present their idea on collapsing an entire
DWDM line card into an optic that they can code for and stick into a
server, I saw the DWDM's vendor's hearts sink right across the table
where I sat. This was 3 years ago.

The vendors need, as you say, someone with a bold enough vision to pivot
the tradition.


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