[e2e] Cannara's views

David P. Reed dpreed at reed.com
Fri Apr 13 08:27:00 PDT 2001

I changed the subject line because this has nothing to do with Outer Space.

For the students and others that might actually find Cannara's views 
plausible, let me offer another clear point of view.

There are two things that Cannara says over and over.

1) The current internet protocol doesn't "optimize" the use of new 
technologies (or incorporate those theoretical results that are closely 
tied to the special properties of those cool new things).

2) New phenomena weren't anticipated in the original design.

(1) is true.  The current internet protocol NEVER "optimized" the use of 
any technology.  So what?  That was part of the design philosophy.  In 
order to be flexible enough to incorporate heterogeneity and change, you 
can't optimize for a particular technology.  More importantly, if you do, 
you die at the next change.

(2) is wholly false.  The original design philosophy was based on a 
principle of humility - we KNEW we couldn't ever anticipate new apps or 
patterns of use.  At the time, computer-computer connections over LANs were 
thought to be important.  I had designed a protocol to "optimize" what we 
thought might happen in those environments (as had PARC, with PUP).  Rather 
than "fork" the design to pursue our own egotistical desires to demonstrate 
genius in a narrow subset of networking, both groups ended up supporting 
the incorporation of a couple of the important insights into a 
far-from-optimal Internetworking approach.  And guess what?  It paid off.

Lots of folks still believe that we are wasting computer cycles by not 
writing code in hand-tuned assembly language.  While true, that's wholly 
irrelevant.  The gain in portability, flexibility, and so forth is 
thoroughly obvious when you step back.

Similarly, the success of the Internet (its flexibility and scalability 
well beyond any of its '80s contemporaries) is thoroughly obvious - 
goodness me, I'd just love to try to build a net that can support 
commercial applications and services of this scale and diversity on the 
X.25 networks or the ATM SVC networks.  And if congestion turns out to be 
better controlled by deploying twice as much fiber as needed, that seems to 
me to be both theoretically and practically sound.

Hardware is now a commodity that is easily spent, something that 
theoreticians have not come to understand in their framing of 
"optimization" problems.  The boundary conditions of any attempt to 
optimize should incorporate the tradeoff between adding resources and 
adding control complexity.  [Students who want to productively rebel 
against their teachers and textbooks would do well to focus on that one 
fact.  E.g., rather than optimizing the utilization of a link, determine 
the optimum tradeoff between controlling the utilization and buying another 
link, as a function of price.]

As far as competence is concerned, sometimes simplifying the problem and 
focusing on real issues is the most competent thing one can do.  Narrow 
specialists often miss the big picture. 

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