On Sat, Apr 23, 2005 at 01:21:46AM -0700, Jonathan Stone wrote:
> 
> quoting David's susggestion again:
> 
> In message <20050413172910.GM6156@che.ojctech.com>, David Young writes:
> 
> >[...]
> > Actually,
> >I think that the the IPv4 address selection should resemble IPv6 address
> >selection, where the "scope" of the destination address is considered
> >(global, link- or site-local), and a source address with the same scope
> >is preferred.  IPv4 should likewise prefer a private sources (192.168/16,
> >10/8, ...) when the destination is private, a link-local (169.254/16)
> >for link-local destinations, and global source for a global destination.
> 
> As Thor noted in message, <20050413213934.GA14667@panix.com>, this
> idea does violence to RFC-1122 ``Strong ES'' model, which many of us
> rely on to a greater or lesser degree.

I am reading 1122 again and I am not so sure.  The RFC says "the physical
interface that corresponds to the IP source address..." and so forth; but
David is talking only about hosts that have multiple IP addresses on the
_same_ interface.  What David is proposing does, though, run contrary to
the introductory text about the _intent_ of the strong host model, that
"it tends to model a multihomed host as a set of logical hosts within the
same physical host" and to some extent to the principle of least surprise.

I don't think David is suggesting that either heuristic he is proposing
should be the default -- is he?  David?  I can certainly see where they'd
be useful.

Thor