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From: Adrian Knoth (adi_at_[hidden])
Date: 2006-03-31 10:15:51


On Fri, Mar 31, 2006 at 09:36:31AM -0500, Jeff Squyres (jsquyres) wrote:

> I have no personal experience with IPv6, but one thought that strikes me
> is that the components might be able to figure out what to do by looking
> at/parsing either the hostnames or the results that come back from
> resolving the hostname...?

Yes. You can ask the resolver for v4, v6 or any of them.
The libc functions are standardized and handle both.
The socket family, too. You just have to specify whether
to use AF_INET or AF_INET6. That's all.

Due to the new lookup functions, DNS lookups now return
a linked list of dynamically allocated memory containing
the results for probably multi homed hosts. The common way
is to iterate over this list, try every given address/information
and manually free the memory afterwards.

The whole process in its naive implementation is straightforward.

Are we getting trouble with listen()/accept()? If we use
v6-mapped-v4 (::ffff:a.b.c.d/96), we only have one socket
to bind to and to listen on. But if we create two separate
sockets, are they non-blocking to each other? So to say:
does OMPI already handle more than one listen socket?

Would this be a problem in case of a btl/tcp6-component?

(I really prefer the v6-mapped-v4 solution with a single
 socket, thus eliminating this problem)

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