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When ANY router becomes as reliable as a dumb TDM device, then maybe we can begin collapsing the POP topology. However, the very nature of the Internet almost prevents this reliability from being achieved (having a shared control and data plane seems to be the primary culprit).

Uhm. Actually, control & data planes are rather separate inside modern routers. What is flaky is router software. That's what you get when your router vendor sells you 1001 way of screwing up your routing :)

Router hardware can be pretty flaky as well... ;) I was more referring to the nature of IP. With the exception of IS-IS, all IP control plane protocols are subject to abuse/attack by the same data plane that they are intending to control.

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There are routers out there today that can single-handedly replace entire POPs at a fraction of the rack, power, and operational cost. Hasn't happened, tho.

I know two boxes like that - one is broken-as-designed, with copper distributed fabric; another (courtesy of VCs who managed to lose nearly entire engineering team mid-way but hired a bunch of marketers long before there was anything to ship) is still in beta.

Ouch.

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I don't like wasting ports for redundant n^2 or log(n^2) interconnect either, but router and reliability mix like oil and water...

Actually, not. A router is a hell of a lot simpler than a Class-5 switch, particularly if you don't do ATM, FR, X.25, MPLS, QoS, multicast, IPv6, blah, blah, blah.

There are opponents to this assertion. I haven't seen enough of what's in the sausage to make a firm statement either way. What I do know is that the class-5 switch is designed to save lives. A router is designed to fill vendor wallets. That, coupled with experience in the field suggests, coupled with dogma and the high-level of sensitivty to being burned repeatedly, suggests that the trend for chassis redundancy requiring massive amounts of wasted space, unnecessary hierarchy, and added complexity to continue. Ces't la Vie!

Demonstrably (proof by existence), those switches can be made reasonably reliable. So can be routers. It's the fabled computer tech culture of "be crappy, ship fast, pile features sky high, test after you ship" aka OFRV's Micro$oft envy, which is the root evil.

Yep! -chris

--vadim