Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site peora.UUCP Path: utzoo!watmath!clyde!cbosgd!ihnp4!qantel!hplabs!tektronix!uw-beaver!cornell!vax135!petsd!peora!jer From: jer@peora.UUCP (J. Eric Roskos) Newsgroups: net.mail Subject: Re: Mail routing -- problems showing up Message-ID: <1424@peora.UUCP> Date: Sat, 3-Aug-85 22:45:12 EDT Article-I.D.: peora.1424 Posted: Sat Aug 3 22:45:12 1985 Date-Received: Tue, 6-Aug-85 11:30:05 EDT References: <1386@peora.UUCP> <9569@ucbvax.ARPA> Organization: Perkin-Elmer SDC, Orlando, Fl. Lines: 39 > If not, check to see if you have a gateway for .ESU.UUCP, which you'd have > to have, even if you were a simpleton site that had only one connection to > bounce to, since .ESU is the "top-level" for UUCP, an artificial domain set > up for our purposes (shhh... don't tell anyone...;-) > > There's no reason to send everything you have to a UUCP central server. I think if you do this, you have some real problems. If you have only one connection, your routing is trivial, so that is not a good example. If you have two or more connections, either you have to know the path to ESU (even if that path is just the name of the next site down the line, which I think it can be shown requires that you need to know the entire path, even if it's not kept in your database), or you have to guess. If you guess, you could guess wrong quite easily. It is easy to demonstrate this. Consider an imaginary UUCP network in which the graph is partitioned into two disjoint subgraphs except at your site, which connects the two. Well, you have to choose one of the two connections you have, and if there are an equal number of sites in each of the subgraphs, half the time you will guess wrong. If you do better than that, either you have to have: (a) a map of the whole name space, in some form, or (b) a smaller map of some central nameservers (or an arbitrarily chosen nameserver for each subdomain, in my "distributed" example from my previous posting). (a) is what you are arguing against all a long, and (b) is what you just claimed you don't need. Thus the only alternative is that you must guess, and some proportion of the time, you will guess wrong, which is what I set out to show. In the real world, of course, the graph is not partitioned so neatly; this reduces the probability that you will guess wrong, but does not by any means reduce it to zero (or even close to zero, I don't think). -- Shyy-Anzr: J. Eric Roskos UUCP: ..!{decvax,ucbvax,ihnp4}!vax135!petsd!peora!jer US Mail: MS 795; Perkin-Elmer SDC; 2486 Sand Lake Road, Orlando, FL 32809-7642 "Vg frrzf yvxr hc gb zr."