Path: utzoo!attcan!uunet!ncis.tis.llnl.gov!mcb
From: mcb@ncis.tis.llnl.gov (Michael C. Berch)
Newsgroups: comp.mail.sendmail
Subject: Re: Short-circuiting a route
Keywords: sendmail, smail, domain names
Message-ID: <266@ncis.tis.llnl.gov>
Date: 30 Jun 89 00:13:26 GMT
References: <1039@aber-cs.UUCP>
Organization: Postmodern Consulting, Pleasanton CA USA
Lines: 46

In article <1039@aber-cs.UUCP> pcg@cs.aber.ac.uk (Piercarlo Grandi) writes:
> NO! Leave those routes alone. If you try to short circuit, you will find that
> a lot of domainized names are NOT on the internet, or there are good reasons
> to use a UUCP channel to get at them, etc... Altering a source route for
> such cases may well create loops.
> 
> Let's repeat for the zillionth time that "a.b.c" is a *name*, and does not
> imply *anything* on the connectivity of "a.b.c" to any network, e.g. the
> internet (as it should be; that is why top level domains that are network
> names, e.g. bitnet or uucp, are very much frowned upon).  Domainization is
> only a scheme to generate reliably unique names, not to give routing hints;
> these should be based on maps. And you should never try to second guess
> somebody's else's maps...

I beg to differ, and hold the following as tenets:

1. The Domain Name System, as implemented in the U.S. by the set of
root name servers operated on behalf of DDN and NSFNet, and
implemented in other countries via central naming authorities, has
preempted the field of host naming and mail forwarding.  Thus the "c"
in "a.b.c" must be an approved top-level domain, and "b.c" must be a
domain known to the root name servers.  Otherwise the address is
illegal and I do not feel any compunction about bouncing it.
(Note to Mr. Grandi, this implies nothing about connectivity or routing.)

2. Fully-qualified domain names (FQDNs) shall predominate in any
hybrid or mixed-mode address, including a source route.  The
legitimate forms of address are those implied by reading the
appropriate Internet RFCs.  Other forms of address, including UUCP
bang paths, are obsolete, and are honored only as a matter of comity
and backward compatibility by Internet hosts.  

3. Source routes are not favored, since they make assumptions about
connectivity outside the local domain of the sender, and may operate
to increase costs for forwarding hosts and delay messages.  To
manage these costs and reduce delays, forwarding hosts should attempt
to be maximally efficient in routing, including maximum use of the DNS
MX/forwarder distributed database.

I guess this qualifies as strong Domain Absolutism, but heck, I think
it's the only way to get people to get rid of obsolete stuff and join
the commmunity.

--
Michael C. Berch  
mcb@tis.llnl.gov / uunet!tis.llnl.gov!mcb