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Path: utzoo!watmath!clyde!burl!ulysses!allegra!scherzo!petrus!bellcore!vortex!lauren
From: lauren@vortex.UUCP (Lauren Weinstein)
Newsgroups: net.mail
Subject: Domain routing in UULINK
Message-ID: <738@vortex.UUCP>
Date: Sun, 11-Aug-85 20:10:23 EDT
Article-I.D.: vortex.738
Posted: Sun Aug 11 20:10:23 1985
Date-Received: Sun, 1-Sep-85 06:05:49 EDT
Organization: Vortex Technology, Los Angeles
Lines: 76

I was hesitating about entering this current fray, but I guess I'd better.
There are indications that demand for UULINK is quite high, and there's
the possibility that there could be a lot of nodes running it
in some not-too-long period of time.  As such, the manner in which
I handle domain support inside the package may be of some
interest, since there are going to be a lot of nodes out there using it.
(Note: UULINK is my MSDOS uucp/mail/basic netnews package which is starting
to go out now).

Basically, I took the class-3 (complex) site description and implemented
the basic functionality to make it work.  Both User@Site.Domain and
...!Site.Domain!User syntax is supported, so all of the compatibility
issues do work.  I went to great pains to come up with something that
would work both when talking to dumb sites that will never change
their software and to smart sites.  I also handle both left-right and
right-left address parsing issues, but I won't go into the details
of that here.  The basic functionality of my domain handling is 
based on a single file, which can be small or large as desired. 
A fragment from a sample file looks like this:

cbpravo.cbosgd.UUCP	cbosgd			3
cbosgd.ATT.UUCP		cbosgd			3
ATT.UUCP		cbosgd			3
allegra.UUCP		allegra			1
ihnp4.UUCP		ihnp4			3
ism780.UUCP	        ism780			1
bellcore.UUCP		bellcore		1
trwspp.UUCP		trwspp			1
research.UUCP		ihnp4!research		1
sdcrdcf.UUCP		randvax!sdcrdcf		1
psivax.UUCP		randvax!sdcrdcf!psivax	1
.UUCP			ihnp4			3
.ARPA			ihnp4!ucbvax		2
.GOV			ihnp4!ucbvax		2
.COM			ihnp4!ucbvax		2	
.BITNET			ihnp4!ucbvax		2
*default*		ihnp4			3

This table provides all of the routing requirements for a small site
with a "few" outside connections.  It includes full routing information
for sites where full routing is known to be best (where full may
mean a multi-hop path--it does not necessarily imply a one-hop path, just
that the path is fully qualified to some point), and provides for
routing to "smarter" sites for domains and/or subdomains where
we don't have enough information for full routing.  It also
handles the real-world situation of smart and dumb hosts.  The
number in the third field specifies the "smartness" of the final
host in the path.  3 is smartest, we can drop full domain addresses
right in its lap.  2 is dumber, and 1 is "dumbest" yet.  There are also
a variety of alphabetic options that can be further used to control
the manner in which addressing information is passed along, in modes
that range from very smart to very simple.  

The point of this is that it WORKS.  My Beta sites have been using
it to route User@Site.Domain addresses through the existing network
and through other sites running my code.  My own code falls into
class 3 (smart) so even the lowly PC's can handle the domain
addresses even with limited resources.  The routing table can be as
complete or simple as the individual site wishes, depending on how
much you want to (or can) push off onto other sites with more
complete tables.

Note that the word "dumb" in this case says nothing about the 
intelligence of the system administrators at a site, it only
refers to the ability of a site to handle domain addresses
in various forms!

One of the advantages of this system is that it requires very little
(if any) cooperation from other hosts, since it will happily route
through dumb hosts as well as smart ones.  I don't put it forth as
THE solution to the routing problems, but I mention it as a
solution that I've found to work well in my MSDOS package.

--Lauren--

{ihnp4, decvax, seismo, clyde, trwrb}!vortex!lauren