see below...
On Thu, 21 Sep 2000, Andrew Morton wrote:
<snip>
> Yep. 3c905B. 905C and most of the Cardbus NICs.
>
> I don't know how useful the whole link-state-change-interrupt thing is
> in practice. The HA guys would, I suspect, say "thanks very much" and
> continue to use application-level heartbeating, as they should.
>
> We (I) need to ask them, and verify that there is actually a use for
> this interface before running away and coding stuff.
One use I have in mind is for mobile devices, eg. a laptop that has
multiple network interfaces. There is a protocol called "mobile IP"
(RFC2002) that lets you roam around various points of attachments to
various networks, and keeping the same home IP address via tunnelling
tricks. In order to hand off from one medium to another quickly, eg. wired
lan to wireless, getting hints from lower layers (eg. via the select() on
a socket interface) can assist user mode software in making snappy
handoffs. Many present implementations rely on timeouts for this kind of
thing, encouraging 'beacon' rates within the network to be set higher than
is desirable.
There is Linux software for RFC2002+ support today -
http://www.cs.hut.fi/Research/Dynamics/
Having link layer indications about availability would make performance
much snappier and implementations more elegant.
Roger.
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Roger Venning \ Do not go gentle into that good night Technologist \ Rage,
rage against the dying of the light. Telstra Research Labs \Dylan Thomas
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