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

Mark Tinka mark.tinka at seacom.mu
Sat Jun 20 17:50:27 UTC 2020

On 19/Jun/20 20:19, ljwobker at gmail.com wrote:

> >From the vendor standpoint, the market has never been able to agree on what makes a "core" application.  If I have five "big" customers, I guarantee you that:
>  - one of them will need really big ACLs, even though it's a "core" box to them.
>  - one of them will want to terminate high speed L2VPN circuits, even though it's a "core" box.
>  - one of them will need to do hierarchical shaping and granular QoS, even though it's a "core" box. 
>  - one of them will want to have lots of headroom in the FIB (2-3x today's global tables) ... even though it's a "core" box.
>  - one of them will want to buy something that they can "migrate out to the edge" one day...
> Say it with me:  "even though it's a "core" box"
> This puts me (as the vendor) in a super weird spot... I can try to create a card/PID that addresses *some subset* of this, charge a lot less for it, and hopefully sell a bunch.  Or I'm left creating something that I can sell into that broader market, but then that thing has to "do all the stuff" and I'm going to charge for it appropriately.  
> The physics dictate that "Really High Speed Silicon" does not exist which can solve all of those things.  I can solve SOME with a given chip design, but not all. 

Well, if I'm honest, it's the vendors who created "tiers" back in the
day, so they can sell boxes in the way they did, and still do.

Ever since Ethernet became the gold standard, what a core, edge,
peering, branch, e.t.c., box is has been meaningless. It was meaningless
before Ethernet (I mean, to some, the Cisco 3640 was a core router,
while to others it was a peering router), but it's more meaningless in
the days of Ethernet.

The reason the ASR9000 sells better than the CRS or NCS 6000, is the
same reason the MX sells better than the PTX or T-series. It's all about

So now, vendors who are able to build boxes that can license Ethernet
ports will be the winners, because I don't have to pay the upfront capex
for the entire card, and can just grow as I need. The Transport boys
have been doing it for so long, why can't the IP boys do the same? The
good news is, they have started.

Secondly, and perhaps more importantly, if vendors can build around a
single ASIC across a multitude of platforms, then there is hope. If you
have to build a different ASIC for every tier of a network, you end up
with the issues you raise, above. The reason the MX does so well is
because in addition to being an Ethernet platform, it uses the same ASIC
(since Trio, to be clear), which gives Juniper and its customers plenty
of flexibility across a variety of applications.

There is a lesson, here, to be learned.


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