Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rutgers!sri-unix!hplabs!amdcad!phil
From: phil@amdcad.UUCP (Phil Ngai)
Newsgroups: comp.mail.headers,comp.mail.uucp
Subject: more about autorouting
Message-ID: <14396@amdcad.UUCP>
Date: Tue, 20-Jan-87 00:37:07 EST
Article-I.D.: amdcad.14396
Posted: Tue Jan 20 00:37:07 1987
Date-Received: Tue, 20-Jan-87 20:40:00 EST
Organization: AMDCAD, Sunnyvale, CA
Lines: 72
Xref: mnetor comp.mail.headers:94 comp.mail.uucp:154

Since I posted my claim that uucp routed mail should not be rerouted,
I have gotten some responses to the effect of "but it's more expensive
if you don't reroute".

For those who just dropped in, my claim (or plea) was:

1) don't reroute a!b!c!joe
	a) even if you think d!c!joe is better
		o your map data could be out of date
		o site d's map data could be wrong about its costs
		o sender may know site d is down
	b) even if you directly connect to site b
		o sender may be trying to test site a's connectivity

2) do route joe@c.domain
	you have to route this anyway.

The objective of saving money on network expenses is a good one. I would
like to point out some important factors, which many readers may know
but I doubt all readers do:

1) cost is not a linear or even monotonic function of distance. That
is, it is often cheaper to call out of state than within the state.

2) a lot of bad cost data is floating around out there. Many sites,
for example, have assigned a low cost to calling ihnp4, a site which
no longer runs as well as it used to.

3) There are many routes which are less expensive than they may
appear.  Companies such as mine often have internal networks with
fixed (and low) charges between their facilities. These networks are
needed to do business anyway and a little extra usage costs very
little, particularly at night when these networks are almost
completely unused.

Still, it is possible that one day, all sites will be sending in
regular, consistent map updates. If this day comes to pass, I still
see the loss of the ability to test network connectivity as posing a
serious problem for network maintenance. There is also the issue of
not having a manually routed fallback for emergencies.

I would like to propose a way to keep the network managable and still
provide the benefits of auto-routing, overridable by the knowledgeble
user when needed. Simply, encourage people to use domain addresses.
These have to be auto-routed. There are several ways to provide
encouragement. Simplest is to ask people to and write it into the
various news and mail documents. Second, make it the default for news
distributions, as that is where most of the long paths come from.

Third, and most facist, is to start bouncing ! routed addresses.  To
avoid breaking the network maintenance features I am arguing so
strongly for, the sites which bounce ! routed addresses would check
for a header line of the form "Netman: loopback check" or "Netman:
routing around dead site", etc. Just check for the equivalent of the
moderated newsgroups Approved header line and if present, let it
through. If it is missing, send it back with a msg advising the sender
to use domain addresses.

Note the difference from proposals to add a "Reroute: no" field in
that a few sites implementing the "Netman" field would encourage many
sites to start using domain addressing while a few sites implementing
the "Reroute" field would not have much effect beyond encouraging
people to be lazy about choosing paths because they know someone else
will take care of it.

Comments? 
-- 
 Social security is welfare for the elderly.

 Phil Ngai +1 408 749 5720
 UUCP: {ucbvax,decwrl,hplabs,allegra}!amdcad!phil
 ARPA: amdcad!phil@decwrl.dec.com