Path: utzoo!attcan!uunet!samsung!usc!apple!snorkelwacker!ira.uka.de!smurf!urlichs From: urlichs@smurf.sub.org (Matthias Urlichs) Newsgroups: comp.mail.uucp Subject: Re: Paths and Precedence (Re: Question about From: lines) Message-ID: Date: 17 Jul 90 18:45:16 GMT References: <[$6je2.vl6@smurf.sub.org> <1990Jul16.203728.501@chinet.chi.il.us> Organization: University of Karlsruhe, FRG Lines: 33 In comp.mail.uucp, article <1990Jul16.203728.501@chinet.chi.il.us>, les@chinet.chi.il.us (Leslie Mikesell) writes: < In article <[$6je2.vl6@smurf.sub.org> urlichs@smurf.sub.org (Matthias Urlichs) writes: < < [ UUCP-Non-routing ] < >This is based on the simple assumption that the next site along the path < >really should know better how to get to the destination than I do, since it's < >assumed to be closer to it. < < Hmmm, it should be fun when 2 sites doing this each decide that the other < is the best next-hop toward the end point. < You're right; that's why mailers have a maximum hop limit... A better solution might be to remember the message-ID and to generate successively longer paths if the message shows up again (or to examine the Received:-headers, which aounts to the same thing). Unfortunately I haven't found a good way to integrate that into MMDF yet, and I am not going to search unless it becomes a problem, which it isn't now. Anyway, ping-pong routing like that will not happen unless a link gets downgraded or dead, and only if this downgrading isn't propagated in the maps. The latter can happen when I adjust link costs without making them public, or when some site doesn't use the latest maps. So, that situation can be avoided by publishing a new map entry with downgraded link cost, but using the old link cost for local routing until everyone else has the new map. Alternately, it can be avoided by never downgrading a link, which is what I am doing -- instead, links tend to get better as more and more people discover the joys of faster modems. ;-) -- Matthias Urlichs -- urlichs@smurf.sub.org -- urlichs@smurf.ira.uka.de Humboldtstrasse 7 - 7500 Karlsruhe 1 - FRG -- +49+721+621127(Voice)/621227(PEP)