Subject: Re: Impending Publication: draft-iab-service-id-considerations-01.txt

From: Zefram <[email-masked]>
Date: Mon, 16 Jun 2003 22:27:23 +0100

|    If intermediate systems take actions on behalf of one or more parties
|    to the communication or affecting the communication, a good rule of
|    thumb is they should only take actions that are beneficial to or
|    approved by one or more of the parties, within the operational
|    parameters of the service-specific protocol, or otherwise unlikely to
|    lead to widespread evasion by the user community.

I think this statement gives dangerously wide latitude for intermediate
systems to damage end-to-end-ness.  It seems to me that a router should
only do something outside fundamental routing behaviour when this has
been explicitly approved, either through protocol negotiation or through
manual configuration, by sufficiently many affected parties that the
others can't tell that anything out of the ordinary is happening.

To perceive some action as "beneficial to ... one or more of the parties"
does not make it so.  Not only is human history in general littered
with examples of evil done "for their own good", but also within recent
networking history some of the problems that the draft is responding to
have been caused by intermediate systems trying to be helpful.  A major
problem is that most of these attempts to be helpful are attempts to
be helpful to humans, which end up being unhelpful to computers and to
those humans that interact with computers as we do; few people outside
the IETF are truly competent to judge what is beneficial to someone
else within the context of computer networking.  Do not underestimate
the degree to which computer systems are designed by managers.

In the nexxt clause, it's not clear whether "within the operational
parameters of the service-specific protocol" is intended to be ANDed
or ORed with the "beneficial ... or approved ..." clause.  If it is
intended to be ORed, I find this also to be dangerously broad.  Finally,
"unlikely to lead to widespread evasion" is another criterion that anyone
who needs to be told this rule won't be competent to judge.

Overall, I think that, particularly in such an official statement as
this, the IAB needs to be very conservative about Internet architectural
matters.  We should maintain the current situation wherein firewalls are
recognisably a breach of the Internet architecture, at least until we've
worked out a way to do them that doesn't cause surprising behaviour.
This Internet works (ish), and we need to keep it that way: if we break
it now, we'll probably never be able to get the popular momentum required
to replace it with a new one that works.

-zefram

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From: Melinda Shore <[email-masked]>
Date: Mon, 16 Jun 2003 18:19:50 -0400

> others can't tell that anything out of the ordinary is happening.

Where do you think this leaves rewriting DSCPs at network
boundaries?

But anyway, the document is a statement of principle rather
than a standard, and I'm not sure that it's possible to be
absolute about these things when the interests of the user
may be counter to the interests of the network
administrator.  That's not quite true - it is possible to be
absolute.  But I don't think it's likely to produce good
results or progress on what really are some rather difficult
and sometimes subtle questions about what happens between a
sender and a receiver.

Melinda