Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!uw-beaver!apollo!ulowell!page
From: page@swan.ulowell.edu (Bob Page)
Newsgroups: comp.mail.uucp
Subject: Re: some (hopefully) useful comments about mail routing
Message-ID: <9447@swan.ulowell.edu>
Date: 4 Oct 88 00:23:00 GMT
References: <433@manta.pha.pa.us>
Reply-To: page@swan.ulowell.edu (Bob Page)
Organization: University of Lowell, Computer Science Dept.
Lines: 58

brant@manta.pha.pa.us (Brant Cheikes) wrote:
>I hear that the new smail under development will not support dynamic
>routing which, if true, renders this discussion moot.

Not moot at all, as no site is forced to use any MTA with such
restrictions.  We don't run smail here, thank you.  If we did active
rerouting (we don't), we'd keep doing it regardless of what smail did.

>Yet if we are to eliminate dynamic routing,

We're pissing into the wind here folks.  Mel has heard all the
arguments, he isn't convinced. If you don't like it, do your best
not to send mail through rutgers.

If a site isn't being network-social (like sun), tell them about it.
If their attitude is similar to "we have better things to do", do
your best not to send mail through them.

If you find a good site, praise them.

>Principle of PASSIVE-ROUTING: "I only know reliably about my
>neighbors, but if someone asks me to next-hop to non-neighbor site
>baz, I have the right to assume that the baz in question is the baz in
>the maps and route accordingly."
>
>Principle of DYNAMIC-ROUTING: "I always know the correct path to the
                                                  ^^^^^^^
>destination, and if I don't, someone along the new path I generate
>does and will reroute accordingly."

'correct' should be either 'shortest' or 'least cost'.  Any site that
reroutes does so because it is shorter or costs less, not because it
is correct.  (and there's the rub!)

I think that rerouting to a rerouting host (last clause of the DYNAMIC
definition) is the worst sin possible.  If you don't know the host,
at least leave the path alone.

I have a third possibilty - call it DOMAIN-ROUTING - I currently don't
do it, but have given it some thought.  Given a path like:

	host1!host2!another!even!smore!host.foo.edu!host7!host8!user

I claim I can *legally* change that to

	host.foo.edu!host7!host8!user

if I can determine that I know how to get to host.foo.edu.  All
Internet hosts capable of MX should be able to.  UUCP-only sites will
only be able to do this a small percent of the time, I suspect.  The
theory is that there should never be more than one site named
host.foo.edu - so cutting out the intermediate middle hosts is OK.

Comments?  I know the purist arguments about path testing.

..Bob
-- 
Bob Page, U of Lowell CS Dept.  page@swan.ulowell.edu  ulowell!page