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Path: utzoo!linus!philabs!cmcl2!seismo!harvard!talcott!panda!genrad!decvax!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: <1431@peora.UUCP>
Date: Mon, 5-Aug-85 08:46:07 EDT
Article-I.D.: peora.1431
Posted: Mon Aug  5 08:46:07 1985
Date-Received: Sat, 10-Aug-85 23:38:53 EDT
References: <3018@nsc.UUCP> <2875@topaz.ARPA> <4787@mit-eddie.UUCP> <1022@sdcsvax.UUCP>
Organization: Perkin-Elmer SDC, Orlando, Fl.
Lines: 65

> For example, suppose I'm a non-UUCP arpa site that wants to send to
> ihnp4!cbosgd!mark.  I could write this as
>         ihnp4!cbosgd!mark@BERKELEY
> Of course, mark might have to reply
>         ihnp4!ucbvax!myname@mysite.ARPA         (excuse me, the name is changed)
> So far, no good--the "@" has top precedence in the 1st example,
> lowest in the 2nd.

Why?  Who says that Mark has to write paths with the same syntax you do?
[We're assuming that for some reason Mark actually wants to write the path,
instead of an address -- which may well be a valid assumption sometimes.]
Without getting into endless repetition, it is perfectly reasonable that on
your "non-uucp" network, "@" might have precedence over "!".  It is also
perfectly reasonable that "!" might have precedence over "@" on Mark's.
It is only unreasonable when, for some reason, you require a uniform path
language for both networks.

> However, why couldn't these two be:
>         berkeley!ihnp4!cbosgd!mark
>         ihnp4!berkeley!mysite!myname
>
> The first is completely compatible with every UUCP site in the world.

Because the latter example requires that "berkeley" know how to translate
"mysite!myname" into a routing or addressing format that is correct for
your network.  This is especially hard when the destination site is not
on the network the UUCP gateway connects to -- i.e., when an intermediate
network has to be used to get to the final destination network.

By way of example, consider the following.  Suppose I am on UUCP.  There is
another network -- and let's say it's some sort of secret network you at
the UUCP gateway can't get the specifications for -- that is gatewayed to
the ARPAnet.  Now, how would Berkeley know that
	ihnp4!berkeley!nudet.ABC!gmas
was to be translated to
	seclia##tnwmon#nudet#gmas@ABC-GW.MIL

Furthermore, suppose ABC-GW.ARPA doesn't really care about UUCP at all.  So
you can't send them nudet.ABC!gmas@ABC-GW.ARPA and expect them to convert
the UUCP address for you. (I.e., ihnp4!berkeley!abc-gw.MIL!nudet.ABC!gmas
would not work for this reason.)  Having them do this would require that
they acknowledge sufficient importance of the UUCP network (or of the sender)
to invest the effort to make ABC-GW recognize nudet.ABC!gmas and translate
it appropriately -- something they may well not be willing to do.

The point is, the amount of knowledge required by UUCP gateways is
substantially increased if you require gateways to translate pure-UUCP
paths into acceptable paths (or just addresses) for arbitrary other-
gateways, especially if the destination address is not on a network
directly accessible to UUCP.  Alternately, it requires that non-UUCP
gateways into other networks have knowledge of the UUCP addressing syntax.
(The difference being that in the first case, your UUCP gateway generates
the complete address as it would appear on the network you are gatewaying
onto; in the latter case, you just put the leftover part of your UUCP path
into the local-part of the address for the next gateway down the line and
require it to make the translation.)
-- 
Shyy-Anzr:  J. Eric Roskos
UUCP:       ..!{decvax,ucbvax,ihnp4}!vax135!petsd!peora!jer
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