Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site fortune.UUCP
Path: utzoo!linus!security!genrad!grkermit!masscomp!clyde!ihnp4!fortune!rpw3
From: rpw3@fortune.UUCP
Newsgroups: net.bugs.4bsd
Subject: Re: sendmail can lose forwarded mail - (nf)
Message-ID: <2047@fortune.UUCP>
Date: Mon, 19-Dec-83 04:02:08 EST
Article-I.D.: fortune.2047
Posted: Mon Dec 19 04:02:08 1983
Date-Received: Tue, 20-Dec-83 06:41:57 EST
Sender: notes@fortune.UUCP
Organization: Fortune Systems, Redwood City, CA
Lines: 29

#R:vax4:-125600:fortune:2000007:000:1249
fortune!rpw3    Dec 19 00:00:00 1983

Hmmmm... the infinite loop problem. I have two suggestions, neither of
which may be ultimately useful becasue implementing them might break
too much old software, but...

1. Yell, scream, demand, insist that systems supply guaranteed universally
   unique I.D.'s on messages. Then you can at least detect loops at the
   cost of caching "recently" seen I.D.'s). [One of the main reasons
   Ethernet has 48 bit addresses, BTW]

2. Having done #1, look at the so-called "hot potato" routing algorithms
   (and friends) that were popular a few years back (especially in
   military work). In particular, there was a PhD thesis by a guy named
   Tajibnakis (sp?) at Univ. Michigan which analyzed an algorithm which
   guaranteed that every site would see every message and no link would
   see it more than twice.  Yea, I know that's better suited to USENET
   ans BB's than to mail, but the real point is: Go back and dig up
   some of the old store-and-fwd routing literature. An awful lot was
   done on that before ARPAnet-style (fully connected all the time)
   became popular.

Rob Warnock

UUCP:	{sri-unix,amd70,hpda,harpo,ihnp4,allegra}!fortune!rpw3
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