Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!mcvax!ukc!dcl-cs!strath-cs!jim
From: jim@cs.strath.ac.uk (Jim Reid)
Newsgroups: net.mail
Subject: Re: Driving on the left side of the road :-)
Message-ID: <257@stracs.cs.strath.ac.uk>
Date: Thu, 11-Sep-86 06:05:21 EDT
Article-I.D.: stracs.257
Posted: Thu Sep 11 06:05:21 1986
Date-Received: Fri, 12-Sep-86 01:58:47 EDT
References: <2279@utai.UUCP>
Reply-To: jim@cs.strath.ac.uk (Jim Reid)
Organization: Department of Computer Science at Strathclyde University, UK.
Lines: 56

In article <2279@utai.UUCP> lamy@utai.UUCP (Jean-Francois Lamy) writes:
>
>I am trying to communicate with a site in Britain, and I think I need
>a basic network topology briefing
>
>The message is destined to site psg.npl.co.uk 
>
>Our mailer sends mail in the uk domain to cs.ucl.ac.uk via X.25.  If I
>remember well, that machine is the gateway to the uk domain, where address
>conversion to the "programming-language-style domains" takes place
>
>But the JANET address of the site I am trying to reach is
>JANET:          jrp%psg.npl.co.uk@uk.ac.ukc
>which seems to indicate that JANET and the uk domain are not one and the same
>(could the uk in cs.ucl.ac.uk be an internetism while the one in ac.ukc.uk is
>a janetism?)

JANET and the uk domain should be one and the same: names in the uk domain
should be registered in the UK Name Registration Scheme - akin to an ARPA
nameserver. The UK ARPA/JANET gateway at UCL takes care of mapping between
ARPA and JANET names and relaying the mail. If your ARPA mailer is smart
enough to kick all uk mail to UCL without an explicit relay, the address
given should be enough for UCL to forward to the appropriate host in JANET.

UCL also copes with such bizarre follies as the reverse domain ordering
we're stuck with. My ARPA domain address is "jim@cs.strath.ac.uk". In JANET,
it's "jim@uk.ac.strath.cs"!! (We'll ignore JANET's long and short names -
they only make this shambles more confusing.)

>Is the real address
>jrp%psg.npl.co.uk%ukc.ac.uk@cs.ucl.ac.uk
>-- assuming we have a direct link to cs.ucl.ac.uk?

Yes. The site you are actually trying to reach is on UUCP and is accessible
through the UK UUCP "gateway" at UKC. They have tried to prevent confusion
by arranging that all outgoing UUCP mail presents addresses in ARPA ordering,
using pseudo NRS names for sites not on JANET - eg user@host.dom.co.uk.

The trouble is that some folk think that these pseudo names are registered
in JANET's NRS when they are not (even though the addresses aren't in JANET
domain order anyway). The folk at UCL rebuild their address tables from the
NRS and they usually take extra information on these pseudo-names from UKC.
Your mail shouldn't have been bounced by UCL.

Perhaps you could contact the UCL postmaster to see what went wrong? Perhaps
their address tables were faulty when you tried sending mail. You could
also try an explicit UUCP route - "...!seismo!mcvax!ukc!psg.npl.co.uk!user"
will work.

		Jim

ARPA:	jim%cs.strath.ac.uk@ucl-cs.arpa, jim@cs.strath.ac.uk
UUCP:	jim@strath-cs.uucp, ...!seismo!mcvax!ukc!strath-cs!jim
JANET:	jim@uk.ac.strath.cs

"JANET domain ordering is swapped around so's there'd be some use for rev(1)!"