[e2e] end of interest
David P. Reed
dpreed at reed.com
Mon May 12 07:54:31 PDT 2008
Jon Crowcroft wrote:
> In missive <4827081A.1090305 at reed.com>, "David P. Reed" typed:
> >>I'd suggest that first-principles thinking is harder than Jon thinks.
> gosh - i thought I just wrote something - i didnt realize andy lipmann's
> medialab goal of telepathy had already been reached and you could figure out
> how hard I thought first principles thinking is....thats neat -
> if you can teach the rest of us that trick, we
> could save a lot of bandwidth and carpal pain
Of course, you are right. I achieved no telepathic insight into your
self-perception of difficulty. Another inapt metaphor from inept writer
committed, admitted, convicted, and sentenced to embarrassment. If I
can save anyone carpal pain I'll license the invention for free.
Nonetheless, I agree with John Day who pointed out much better than I
that perhaps the problem is not to legitimize layer "violations" as good
things, but to recognize that maybe the idea of ordered layering was
injected way beyond its usefulness into the rhetorical framing of
network protocol design, and now threatens clear thinking about a whole
range of important issues.
The end-to-end argument paper attempted to discuss a rationale for
placement of functions in a modular architecture.
That serves (imho) as a far better example of discussion of
architectural principles than the ISO OSI attempt at a
canon/scripture. The ISO OSI model was introduced without a discussion
of tradeoffs (very much the content of the end-to-end argument paper),
as a fait accompli.
Rather than talk about "breaking with a religion" - perhaps it might be
better to talk about the elements of thoughtful design principles again.
The idea of a "connection" or "session" is very useful in some contexts,
but highly distorts the conversation on DTNs which leads to odd
circumlocutions like "connection *less*" networking. Well, if we
hadn't canonized them, we wouldn't have them. Books are a form of
communications, as are TV broadcasts. Neither form of communications
ever called for connections as a concept. So to call them
connectionless implies that they are somehow "exceptional" or
"troublesome". But they are really only troublesome to people so
steeped in the canon that they assume "connections" are first-order
axioms of any theory of communications.
Algebra exists without unique multiplicative inverses. Geometry exists
without the parallel postulate. Communications exists without layers -
especially without "session layers" that presuppose an artificial invention.
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