Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site down.FUN
Path: utzoo!watmath!clyde!burl!ulysses!allegra!princeton!down!honey
From: honey@down.FUN (Peter Honeyman)
Newsgroups: net.mail
Subject: Re: Name space explosion -- first tremors
Message-ID: <531@down.FUN>
Date: Fri, 19-Jul-85 22:29:16 EDT
Article-I.D.: down.531
Posted: Fri Jul 19 22:29:16 1985
Date-Received: Mon, 22-Jul-85 03:17:05 EDT
References: <568@decuac.UUCP>
Organization: Princeton University, EECS
Lines: 149

i don't have a problem with name collisions.  i use the (undocumented)
private host declaration in pathalias to make such hosts invisible.
pathalias then generates routes through but not to these hosts.  my
mailer runs routes given by mail and netnews through pathalias and a
route parser.  i am generally satisfied with the results.

my database currently includes mod.map.uucp, arpa, csnet, bitnet, and
dec enet (with mailnet coming soon).  that's about 10,000 hosts.  i
reiterate:  i don't have a big problem with host name collisions.  i
have a much bigger problem with foreigners (i.e., arpanauts) trying to
shove standards down my throat.

i plan to post a recent edition of pathalias within the next 10 days
(as soon as my correspondents report back that it still works).  the
parser should follow sometime in august.

	peter

appendix:  here's some output from the parser.

==========
princeton!ulysses!cbosgd!ulysses!princeton!down!honey@cbosgd.ATT.UUCP

host ==	ulysses
user == cbosgd!ulysses!princeton!down!honey@cbosgd.att.uucp

the parser found four credible candidates and merged them to get the
result shown.  someone's broken mailer put it in this confused state.

==========
princeton!ihnp4!cfg!ukc!dar@ubu.uucp

host ==	cfg
user == ukc!dar@ubu.uucp

i don't know how this got to me!

==========
princeton!seismo!USER%purdue@csnet-relay.ARPA

host ==	purdue
user == user

note that the parser decided against the two candidate parses that
require bouncing around on arpanet or csnet.

==========
princeton!allegra!ucbvax!vortex!lauren@rand-unix.arpa

host ==	rand-unix
user == vortex!lauren

my database doesn't know about rand-unix -> vortex, but the mail gets
through anyway.

==========
princeton!allegra!ulysses!mhuxj!ihnp4!inuxc!pur-ee!uiucdcsp!shilling

host ==	pur-ee
user == uiucdcsp!shilling

again, no data on pur-ee -> uiucdcsp, but it's ok.

==========
princeton!astrovax!dartvax!forwarder.dartmouth@csnet-relay.CSNET

host ==	dartvax
user == forwarder.dartmouth@csnet-relay.csnet

someone at dartmouth thinks it's good practice to obscure the user name
when gatewaying from csnet; i don't agree.  also, it would have helped
to know the relationship between dartvax and dartmouth (i think the
latter is a "domain").

==========
princeton!ihnp4!ucbvax!pleasant@rutgers.ARPA

host ==	rutgers
user == pleasant

gotcha.

==========
princeton!ihnp4!ucbvax!jk01%tufts.csnet@csnet-relay.arpa

host ==	tufts
user == jk01

gotcha.

==========
princeton!ihnp4!mit-eddie!jfw@mit-ccc.ARPA

host ==	mit-eddie
user == jfw@mit-ccc.arpa

again, missing data prevents a complete parse, but that's ok.

==========
princeton!seismo!hao!hplabs!sri-unix!reihar@ucla-locus.arpa

host ==	sri-unix
user == reihar@ucla-locus.arpa

correct, but only by accident.  using the real host name (ucla-cs)
instead of the alias leads to real trouble.

==========
princeton!seismo!hao!hplabs!sri-unix!reihar@ucla-cs.arpa

host ==	princeton
user == seismo!hao!hplabs!sri-unix!reihar@ucla-cs.arpa

this is a compromise between three reasonable parses.  i'd call it a
complete failure, actually.  hey, no one's perfect.

==========
princeton!allegra!ucbvax!Jon_Tara%Wayne-MTS%UMich-MTS.Mailnet@MIT-MULTICS.ARPA

host ==	mit-multics
user == jon_tara%wayne-mts%umich-mts.mailnet

that's the best it can do until i incorporate mailnet data.

==========
x!y@z

host ==	x
user == y@z

pathological --there actually \is/ a host called x!  since the parser
couldn't get anywhere with down->x and down->y, it ran pathalias on x
and y ran recursively on the result, princeton!clyde!frog!x!y@z.

==========
princeton!meetix.yktvmv@ibm-sj

host ==	ibm-sj
user == meetix.yktvmv

uses the princeton -> csnet link.
 
===========

that's it for the examples.

the total running time for these 14 examples was about 7 seconds cpu
time, 16 seconds real time, on a 750.  for more info, see my paper with
parseghian in the proceedings of the winter '85 usenix (dallas).