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From: gjm@packard.UUCP (Gary J. Murakami)
Newsgroups: net.mail
Subject: Re: Mail overload and so-called "smart" mailers
Message-ID: <393@packard.UUCP>
Date: Mon, 6-Jan-86 17:29:35 EST
Article-I.D.: packard.393
Posted: Mon Jan  6 17:29:35 1986
Date-Received: Wed, 8-Jan-86 06:49:21 EST
References: <17623@styx.UUCP> <3080@sun.uucp> <313@fear.UUCP> <219@gould9.UUCP> <314@fear.UUCP>
Reply-To: gjm@packard.UUCP (59455-GJ Murakami)
Distribution: net
Organization: AT&T Bell Laboratories, Liberty Corner
Lines: 40


Robert Plamondon is oversimplifying the problem without expressing due
consideration to some of us who have lived with mail routing problems
for years.

While some individuals may argue (somewhat justifiably) that routing
(optimization) on ihnp4 is arbitrary, the decisions have been carefully
weighed to try to provide the most benefit for both internal company use
and for many friends and even competitors AT NO COST.  Many people have
expressed their gratitude via mail for the services provided by ihnp4,
but some individuals appear to be ungrateful.

Robert is correct in that pathalias data can be adjusted to alter your
load and change routes in the network.  He also correctly identifies the
a problem in the lack of a perfect way to reflect load and/or queuing
delays. Many of us have recognized and discussed this since the earliest
days of pathalias.  However the problem is more complicated since:

	changes in pathalias costs also affect your neighbors.

An increase in ihnp4's pathalias costs would shift more burden to some
of its neighbors.  We've cranked the data through pathalias before, and
even the recent pathalias errors point to the drastic effect that can be
caused by changes in input data.  We've seen many scenarios (e.g.
allegra, cbosgd, packard, or topaz flooded, ucbvax bypassed).

ihnp4 has several networks with different characteristics, and the costs
have to be weighed carefully to end up with the correct balance
incorporating hops, media capacity/load, neighboring host capacity/load,
mail delivery delays, and local capacity/load.

Quite a while ago, we downgraded ihnp4's cost to HOURLY for 2400/1200
bps connections to non-AT&T sites.  This meant that ihnp4's AT&T
neighbors had to make similar adjustments.  Fortunately the AT&T data is
centrally collected (unfortunately, I still end up doing it).  I'm
willing to take constructive suggestions on what costs to use (in place
of HOURLY).  Keep in mind that we dont want to touch off a pathalias cost
war...

-Gary