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From: jhc@mtune.ATT.COM (Jonathan Clark)
Newsgroups: comp.mail.uucp
Subject: Re: dynamic routing for UUCP mail
Message-ID: <1141@mtune.ATT.COM>
Date: Wed, 12-Aug-87 21:29:29 EDT
Article-I.D.: mtune.1141
Posted: Wed Aug 12 21:29:29 1987
Date-Received: Sat, 15-Aug-87 05:40:20 EDT
References: <915@bsu-cs.UUCP> <13680@topaz.rutgers.edu> <4577@felix.UUCP> <10149@orchid.waterloo.edu> <2707@hoptoad.uucp>
Reply-To: jhc@mtune.UUCP (Jonathan Clark)
Distribution: na
Organization: AT&T ISL Middletown NJ USA
Lines: 44

In article <2707@hoptoad.uucp> gnu@hoptoad.uucp (John Gilmore) writes:
:There are two optimizations that we should be able to safely make for
:rerouting bang-path mail.  (If I'm wrong, please post a polite correction.)
:
:(1)	The uucp domain mail design was such that if a smart mailer
:	finds a path like foo!bar!a.b.c!anything, and it knows how to
:	get to a.b.c, it can throw away the foo!bar! part.  Furthermore,
:	if there are multiple dotted addresses (e.g. foo!a.b.c!d.e.f!g),
:	it can take the rightmost one it knows.  This is because domain
:	addresses are UNIQUE by design.  (People who invent their own,
:	and put them on mail, deserve what they get.)

I don't think that this poses any problems, in general, apart from the
usual 'should I fiddle with a bang path?' question. I certainly agree
with the last point!

:(2)	I've been planning to put in a rerouter here that just shortens
:	paths that go through sites ALL OF WHICH ARE KNOWN TO ME.  That's
:	not to say that I have a link to them, but e.g.
:		ptsfa!ames!ihnp4!cbosgd!ncoast!allbery
:	can be cut down to ncoast!allbery because I have links to ptsfa,

This is very close to something I've thought of putting into smail,
the FAVOURED-HOST list. This would be a list of sites that my site is
flat out guaranteed to be able to talk to (cbosgd, ihnp4, rutgers, codas,
clyde and a couple of others in my world), and consequently I could do a
rightmost scan until I hit a site I know, then short-circuit the lefthand
part of the path. Useful for netnews paths! Comments, anyone?

:	ihnp4, and cbosgd, and can add "ames" to a short list of sites
:	that my neighbors talk to.

Personally I think that's dangerous, quite apart from being unsure
about exactly which "ames" the mail is going to go to. Given the
number of mail and net neophytes around these days, the original sender
very likely knows much less well than a properly maintained database
how to *really* route hir mail. Earlier today I saw a pile of large
articles in transit through this machine going to a site which I talk
to at 9600 baud, but it was going via 2 1200-baud links. I let it go...
-- 
Jonathan Clark
[NAC,attmail]!mtune!jhc

An Englishman never enjoys himself except for some noble purpose.