davecb@yunexus.UUCP (David Collier-Brown) (06/29/89)
We just had an interesting question come up: a machine (not
a person) in a subdomain nearby just moved to a different
subdomain.
ie, machine.org1.foo became machine.org2.foo
If this were snail-mail, I'd know exactly what it should do: send
the postmaster a postcard saying "I moved" and then send postcards to
all its correspondents.
But that assumes a single postoffice that can unambiguously change
the org1 to org2 on all incoming mail. (For a fee (:-)). In the email
universe we have numerous non-identical, sorta-replicated-almost
postoffices which are historical artifacts of the fact that there
are distinct physical networks...
Eventually, all the postoffices will become aware of and consistent
with the domain addressing scheme we've imposed on them. Then the
procedure will appear as simple as the snailmail case. But right now
we aren't quite that rational. And I confess that its probably harder
to change N postoffices manually than to make them "behave"
algorithmically.
So what should the wandering machine do? Try to negotiate N
changes, one for each historical net? (N may be **large**) Wait for
them to converge? Pretend to be both places until it stops getting
mail sent to the wrong place? Or none of the above?
--dave (surely someone's experienced this before...) c-b
--
David Collier-Brown, | davecb@yunexus, ...!yunexus!davecb or
72 Abitibi Ave., | {toronto area...}lethe!dave
Willowdale, Ontario, | Joyce C-B:
CANADA. 223-8968 | He's so smart he's dumb.lamy@ai.utoronto.ca (Jean-Francois Lamy) (06/30/89)
Well, domain names are meant to name entities, and it is often desirable to keep the distinction clear between names of machines and the name assigned to the group of people. So for example when you mail to ai.utoronto.ca the intent is to identify the AI group at U of T, not the machines (neat.ai.utoronto.ca and ephemeral.ai.utoronto.ca that handle mail for that group -- either one will behave properly if you drop mail on its lap destined for that domain). Conversely, you can have more than one mail domain (intended to designate an homogeneous group of people) living on one machine. We actually have theory.utoronto.ca, na.utoronto.ca and ai.utoronto.ca all served by the same two mail machines (we generate the address depending on the person). So the idea is that the machines die, move, but your address stays the same as long as you stay within your organizational unit. If what you have in mind is a division of a company being taken over and moving from whizbang.one.com to newerbetter.two.com, then that case can be handled by having the name server for one.com advertize that mail for user@whizbang should now be sent to newerbetter.two.com, and for newerbetter's mailer to accept such mail. This is partly what the wunnerful MX records on internet name servers are used for. The actual message would not even go to one.com. This sort of improves on the postoffice situation. In the UUCP world, whoever handles mail for two.com would redirect forcibly mail for the whizbang gang to newerbetter for a while, I guess. Virtually, Jean-Francois Lamy lamy@ai.utoronto.ca, uunet!ai.utoronto.ca!lamy AI Group, Department of Computer Science, University of Toronto, Canada M5S 1A4