remember the "diameter of the internet"?

Vadim Antonov avg at exigengroup.com
Wed Jun 19 01:23:49 UTC 2002


On Tue, 18 Jun 2002, Stephen Sprunk wrote:

> Thus spake "Vadim Antonov" <avg at exigengroup.com>
> > 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.
> 
> The data plane is remarkably easier.  The control plane is arguable.

That's synchronous, jitter-controlled data plane, not the asynchronous,
potentially lossy data plane as in routers.  The difference
complexity-wise is significant.  That's why people are able to get much
higher speeds in packet switches than in voice switches.

As for the control plane... I also thought call control to be easy, until
I started to learn about it as a part of my job at Genesys Labs (the
leading CTI vendor).  The seemingly small number of features (call
progress, hold, forwarding, one-step and two-step transfers, conference
calls, predictive dialing, etc, etc, etc) combine exponentially to produce
huge number of states and possible race conditions.  Add to that strong
real-time constraints imposed (foolishly, perhaps) by signaling system
protocols, the resource allocation (as opposed to best-effort behaviour)  
the real fault-tolerance, accurate accounting requirements, interfacing
with large-scale CMS, and you get the picture.

> And without ATM, FR, MPLS, QOS, multicast, etc. nobody will be buying
> your router.

Yep.  Because of the need to integrate with all kinds of OFRV powered
feature-rich networks, not because of any rational need to have those 
features in the first place.

Microsoft did that to software.  Cisco is doing that to networking.  
Being a cynic, I do own some Cisco stock, and wait for Mr. Chambers to
figure out that producing boxes which won't break in few years erodes
company's profits by forcing it to compete against its own old models.
Quite a few people are quite happy with CGS-es on their T-1s :)  eBAY 
prices on perfectly good routers are great, too [tongue firmly in cheek].

> The question is actually whether anyone would pay the cost of a
> perfect router. People complain that today's routers are too
> expensive, and most vendors are going bankrupt or giving up.  Many of
> those were marketing to the "featureless and reliable" niche.

I'm not aware of any whose marketing wasn't focused on the feature
checklist. Not in carrier or enterprise space.  In SOHO segment Linksys is 
making a killing with their cheap boxes.

Note that "perfect router" to me is the one which you plug in and spend 30
seconds configuring, after which it just works.  Your mileage may vary,
but I strongly suspect that a bookshelf full of manuals is not a
desireable attribute of a perfect anything.

--vadim




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