Subject: Re: IP network address assignments/allocations information?

From: Sean Doran <[email-masked]>
Date: Thu, 9 Dec 1999 23:51:39 +0100 (CET)

| so i had a nearby scheme interpreter

yay.  (now go fix all the buggy scheme and lisp packages in -current :) :) :) )

| It seems obvious to me that the only way routing can scale with
| addresses this large is with very aggressive aggregation.

It would work better still with abstraction, hence my (maybe stupid)
questions to Brian and Christian.

| The only way multihoming can work when aggressive aggregation is in
| place is if hosts end up with multiple addresses (one from each
| prefix) and know how to use them intelligently... 

Even trickier: how to get non-local hosts to use them intelligently.

The DNS as a mechanism for policy-based routing (in the sense of
remotely influencing other people's path selection) is not totally
without appeal.  But then again, I'm a loon, and like NAT.

	Sean.

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From: Christian Huitema <[email-masked]>
Date: Thu, 09 Dec 1999 18:25:49 -0500

>Even trickier: how to get non-local hosts to use them intelligently.

This is definitely a research issue. I think however that there are at
least three possible solutions, and so I believe that this is not a very
difficult research issue.

The first solution is indeed what we do everyday: get several addresses
from the DNS, pick one more or less at random, try it, and if it fails try
the next one.

The second solution is when your DNS resolver has acquired some knowledge
of the Internet, and can sort the address list based on expected
performance. Strict provider addressing actually makes this kind of
knowledge acquisition slightly easier, as the knowledge table is
essentially similar to a routing table, and thus subject to the same kind
of aggregation. There are indeed many ways to acquire this knowledge, from
looking at the routing tables to getting feedback from the hosts, and this
is where research becomes interesting.

The third solution requires TCP implementation that have the "zero context"
hacks necessary to protect against SYN flooding attacks. In that case, the
caller simply sends parallel SYN messages to all possible addresses,
continue with the first response, and forgets anything else. Basically, you
trade routing complexity for increased traffic.

A related problem is the support of readdressing, i.e. changing the IP
addresses without losing the TCP connection, but there are already
solutions in the v6 spec.

-- Christian Huitema

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From: Christian Huitema <[email-masked]>
Date: Thu, 09 Dec 1999 18:25:49 -0500

-- Christian Huitema

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From: Keith Moore <[email-masked]>
Date: Thu, 09 Dec 1999 20:01:31 -0500

> performance.

it also assumes that 'performance' is a one-dimensional quantity.

Keith

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From: Keith Moore <[email-masked]>
Date: Thu, 09 Dec 1999 20:01:31 -0500

Keith