[e2e] e2e principle..where??....

afalk at PanAmSat.com afalk at PanAmSat.com
Tue Jun 5 10:44:44 PDT 2001

> I think this is where I'm confused, apparently people have no 
> problems with caches(or proxies when they are used a caches).


Of course I can't speak for the community, but one answer that occurs to me
is that the issue, again, is Internet transparency. Web caches operate at
application level. While shortsightedness in designing invisible web caches
might inhibit future development in http, the notion of even an invisible
web cache shouldn't affect future developments in non-http network services.

> basically e2e is but ONE argument in system design, it is quite
> likely that other factors can outweigh e2e arguments...

This makes me uncomfortable. When new technology is deployed into the
Internet is affects the shared resource that we all use. Breaking with the
design principles that Internet community has adopted should be done very
reluctantly. Let me relate a short anecdote about my life in the IETF. When
I first approached some folks in the IETF about addressing TCP over
satellite performance issues, I was (somewhat ignorantly) seeking to get a
special satellite-friendly TCPng working group created. Some patient folks
in end2end advised me against this by saying that 1) it wasn't necessary and
2)perturbing very widely used end-to-end protocols, like TCP, is like
fiddling with a biological system. The likelyhood of upsetting the stability
of the system in an unforseen way -- risking network collapse -- is high
enough to justify making changes only in extreme cases. A message I took
away from this is that the stability of the network is more important than
optimizations for a single user or community. This doesn't negate your
observation that the e2e principle is one of many considerations but one
needs to keep in mind that other people will have live the impact of your
design decisions. Choose wisely. :)



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