Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!know!zaphod.mps.ohio-state.edu!usc!ucsd!helios.ee.lbl.gov!ncis.tis.llnl.gov!lll-winken!uunet!mcsun!ukc!dcl-cs!aber-cs!thor!pcg From: pcg@cs.aber.ac.uk (Piercarlo Grandi) Newsgroups: comp.mail.uucp Subject: Re: Paths and Precedence (Re: Question about From: lines) Message-ID: Date: 22 Jul 90 19:37:02 GMT References: <++J4QGC@xds13.ferranti.com> <3RK4TQE@xds13.ferranti.com> <269B6560.3F1E@intercon.com> <269D048B.5A0C@intercon.com> <269FEC7D.40E@intercon.com> Sender: pcg@aber-cs.UUCP Organization: Coleg Prifysgol Cymru Lines: 73 X-Local-Date: 22 Jul 90 12:37:02 PDT In-reply-to: amanda@mermaid.intercon.com's message of 15 Jul 90 04:09:33 GMT In article <269FEC7D.40E@intercon.com> amanda@mermaid.intercon.com (Amanda Walker) writes: On the Internet, source routes have been deprecated in favor of domain addresses and mail exchangers. This isn't because of politics, it's because it works better this way. !-@ hybrids and %ification are just source routes in disguise, and they are just as prone to break mail. But that is the problem! Those are not source routes, they are an example of *foreign naming* which is a completely different thing. The so called percent-hack is a way to require the interpretation of a name to be done at a specific host. There is something of the source routine here, but the essential assumption is that only the indicated host knows about such names. For example: "mcsun!ukc!pcg@uk.ac.aberyswtyth.cs"@uunet.uu.net is a relative name, *not* a route, and cannot be faithfully rendered as pcg@cs.aber.ac.uk even if it mostlt works, because the naming conventions of Janet are different from those of the Internet. The above monstrosity is *really* saying that 'uunet.uu.net' should be used to to interpret a non Internet address in the form of a bang path (note that 'ukc' is identified as the one near 'mcsun', but uunet.uu.net may well connect directly to 'ukc', without routing thru 'mcsun', using the reference to the latter only to disambiguate possible confusion iof there is another host called 'ukc'), and 'ukc' should be used to interpret a Janet address, which superficially resembles an Internet address, but plays by totally different rules. My domain bigotry is not based on idealism, it's based experience and on the fact that when I have to send mail to someone with something besides a straight UUCP path or a straight domain address, chances are it will bounce or disappear. The problem here is that you can only avoid relative naming if every netowrk system shares its full directory with everybody else, e.g. if all Janet hosts get registered with the DNS, and viceversa. Unfortunately this is in general possible, and relative name interpretation is necessary. Summary: We have absolute names, e.g. internet ones, whcih are only tenable if there is centralized administrative authority, however lightweight, and a single directory system. We have relative names, e.g. UUCP ones, where a host is uniquely identified by a pattern of neighbours. This name *may* be used for routing, and usually is. We have foreign names, e.g. those that cross the boundary between two naming systems, whatever their flavour, which are kind of address *resolution* relative names/routes (but are not transport routes or relative names), where a succession of gateways is quoted, and it is assumed that only the gateway can sensibly interpret the rest of the address, because only the gateway is assumed knowledgeable of both different naming rules of the mail systems it bridges. It is, I believe, simply *impossible* to get rid of foreign names; IMNHO relative names are better than absolute names, at least if there is no authority with a mandate for naming and clear rules (e.g. ok for ARPA and X.400 and Janet, not ok for Internet and UUCP). -- Piercarlo "Peter" Grandi | ARPA: pcg%cs.aber.ac.uk@nsfnet-relay.ac.uk Dept of CS, UCW Aberystwyth | UUCP: ...!mcsun!ukc!aber-cs!pcg Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk