Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ucbvax!hplabs!pyramid!epimass!jbuck From: jbuck@epimass.EPI.COM (Joe Buck) Newsgroups: comp.mail.uucp Subject: Re: Dynamic vs. passive routing: site rights Message-ID: <2425@epimass.EPI.COM> Date: 25 Aug 88 22:51:53 GMT References: <4902@netnews.upenn.edu> Reply-To: jbuck@epimass.EPI.COM (Joe Buck) Organization: Entropic Processing, Inc., Cupertino, CA Lines: 45 In article <4902@netnews.upenn.edu> brant@linc.cis.upenn.edu (Brant Cheikes) writes: >My question for those who would abolish dynamic routing, is: do you >assume the right to dictate how my machine's resources will be used? Not at all. You are free to bounce mail that attempts to use a path you'd rather that the public didn't use. Also, as we move more and more to automatically generated routes, you can tune your map entry to steer usage away from expensive links. If we ever get to a point where large numbers of sites install active rerouters, we'll start to see things like mail loops, when two sites disagree as to what the best path is. A--B--D--E \ / C---- Here, B!D is an expensive link and the others are cheap. All links are two-way, same cost either way. In the above picture, assume B's database says the cheapest path to E is A!C!E, and A also believes the path is C!E. Now, site C announces it's going down for a few days. Site A changes its data base to take site C out of the map, so the best path to E is now B!D!E. Both A and B are running active rerouters. Somebody on A mails to user@E. What happens? A and B bounce the message back and forth forever, or until somebody's "too many hops" alarm goes off. We don't see much of this these days because only a small number of sites do rerouting. If it ever becomes common the network is wrecked, because of the very large number of possible loops. Now maybe site A justifies aggressive rerouting because A's manager, Mel Cheerful :-), believes his map data is the best in the world and anyone who specifies a different path is wrong. B's admin, Brant Chuckles :-), believes that the B!D link is expensive, and would rather have A handle all mail, but hasn't changed his map entry to cause this, but justifies rewriting paths based on a personal concept of property rights. The reasons don't matter; rerouting is just A Bad Thing. If B doesn't want to send other's mail through D, fine; bounce it, and if the connection is listed in the UUCP maps use the terminal node syntax so only mail terminating at B uses the link. -- - Joe Buck {uunet,ucbvax,pyramid,}!epimass.epi.com!jbuck jbuck@epimass.epi.com Old Arpa mailers: jbuck%epimass.epi.com@uunet.uu.net If you leave your fate in the hands of the gods, don't be surprised if they have a few grins at your expense. - Tom Robbins