[e2e] Protocols breaking the end-to-end argument

Noel Chiappa jnc at mercury.lcs.mit.edu
Sun Oct 25 08:03:03 PDT 2009

[Apologies to all for dipping backwards a ways into the stream, but this
message contained what I felt was an important point to take on, and I didn't
have time/energy to do so last night.]

    > From: Richard Bennett <richard at bennett.com>

    >>> Moors shows that the Saltzer, Reed, and Clark argument for end-to-end
    >>> placement is both circular and inconsistent with the FTP example that
    >>> is supposed to demonstrate it.

    >> I didn't see that at all.

    > Moors points out that TCP error detection and recovery is an end-system
    > function, but not really an endpoint function in the file transfer
    > example.

This is all true, but I still don't see (for reasons such as that the
real-world FTP isn't the 'reliable FTP' the paper talks about) that it amounts
to "[the] argument for end-to-end placement is both circular and inconsistent
with the .. example that is supposed to demonstrate it", which is what I
disagreed with.

But this is not important, I would prefer to move on to a more important point.

    >>> One of the more interesting unresolved questions about "End-to-End
    >>> Args" is why it was written in the first place. Some people see it as
    >>> a salvo in the ISO protocol wars, others as an attack in BBN's
    >>> ARPANET, some as an attempt to criss the divide between engineering
    >>> and policy

    >> I don't know whether to be amused or outraged by this nonsense.

    > I don't know why this question should get anybody upset, it's just a
    > question about the context and motivation of the paper in the first
    > place.

The problem is that it's like asking why Einstein wrote his thermionic
emissions paper. Even in a purely 'history of science' way, this question is
orders of magnitude less important than the question of the correctness of
the technical content itself.

And hoping that knowing exactly (even if one could know such a thing) _why_
it was written will tell you _anything_ about how correct it is, in and of
itself, is utterly misguided. Down that path lies "Transgressing the
Boundaries: Toward a Transformative Hermeneutics of Quantum Gravity".

To even bring the question of 'why was it written' up in a discussion about
the correctness of the technical content is, in a sense, to attack the very
ideals of technical debate, which is _supposed_ to focus on the technical
content, and leave all else (including people, and motivations), out of it.

    > None of the authors was part of the inner circle of the Internet
    > protocol design at the time the paper was written, although Clark was
    > either the Chief Architect of the Internet or on his way to becoming
    > same.

Say what? Reed was still deeply involved in Internet work at that point (he'd
been one of the people making the case to split TCP up into IP and TCP), as
was Clark (who was writing prototype TCP code, and papers based on the
lessons he learned doing so). And the two of them were extremely close
professional colleagues of Saltzer, with offices basically next door to each
other on the 5th floor. And although Jerry didn't go to meetings or write
code, as a key member of that research group, he was definitely thinking
about the things the rest were working on - as can be seen by his other
papers from that time period.

    > I would have expected Cerf and Kahn to write something explaining the
    > architectural decisions they made in adapting the framework to their
    > system

I don't know Vint well enough to say with any confidence, but to hazard a
guess, but that kind of deep design philosophy thing just doesn't seem like
the kind of thing he'd go for - I think his focus was at a different level.

    > Why these three people and why this particular time?

Why them? Because they were very close professional colleagues who habitually
thought at that level (i.e. design philosophy). Why then? Because at that
point they'd been thinking about networking for a while, and had gotten to
the point where they could usefully apply the kind of systems architecture
analysis that group was known for.

    > It's never been explained.

The fact that you could even bother to ask that question, or think that the
answer is of any interest other than in a 'history of science' way, is very

    > there was a lot of friction between the Network Working Group and BBN
    > over the control BBN had over the ARPANET protocols inside the IMP.

Sure, but that was long before the period when 'End-End Arguments' was being
turned out.

    > The interesting problems of the day in protocol design were all behind
    > the curtain to the people who used the ARPANET, and that's frustrating
    > to engineers. ... by 1981, people were well into the second step, and
    > the closed implementation of the lower three layers was a problem.

Huh? Even by 1978 the people active in the Internet project treated the
ARPANet as a black box which we didn't really have much interest in, and
didn't really concern ourselves with it.

Frankly, for most of us, we were up to our asses in alligators getting all
these various new technologies (LANs, etc) up and running, and didn't have a
lot of time to worry about anything else anyway. What little time we did have
for deep thinking went to things like how to better organize OS software to
deal with networking, etc, etc.


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