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Re: network controls are necessary
Thinking about this question (of what the host might know / want) I think
that there are several things that should be teased apart:
1) The address pair does not work because there really is no connectivity
over that path. In that case, presumably routing will catch up pretty
quickly. In the mean time, it is probably unlikely that trying random
combinations will produce better results.
2) The "doesn't work" is in some sense other than connectivity. This has
been alluded to by some folks in the discussion. Trying to get some kind
of service behavior out of address selection is clearly a matter of using
the wrong tool for the wrong problem.
3) There is a corner case of some unusual failure that means that some
locator for the remote host is not useable, but still appears fine in
routing. The mechanisms for resolving locators ought to deal with that,
not the connecting host.
For clarity, I would actually prefer to have the hosts have nothing at all
to do with the locator selection. The host may need a mechanism to say
"this communication appears not to be working" to cause the routing system
to take appropriate local steps.
Joel M. Halpern
At 11:05 AM 12/6/2002 -0500, Bill Sommerfeld wrote:
> If we really want the hosts to make the choice (a concept I am doubtful
> I suppose we could invent a query / response protocol for the purpose of
> asking a routing intelligent server what source /dest pair from a given
> of sources and dests would be a good pair to use.
one problem with that interface is that if the host determines that
the recommended address pair doesn't work and wants to try something
else, it has no idea whether to blacklist the source, the destination,
or both, when it next asks.
and it would be good for scalability if the host could know when it
was appropriate to cache the results.