On 10/26/2010 01:44 AM, Lorenzo Colitti wrote:

On Mon, Oct 25, 2010 at 9:38 PM, Stephen Hemminger
[off-list ref] wrote:

quoted

This is incorrect. When link is lost, routes and address should not be
flushed. They should be marked as tentative and then go through DAD again
on the new network.

That won't help the case I am trying to fix, which is the case where
the new link has a global prefix different than the old link. Marking
the addresses as tentative will simply make them pass DAD and come
back as soon as link comes back. But since they don't match the prefix
that is assigned to the new link, they are unusable, because packets
can't be routed back to them.

The old addresses will become deprecated, and eventually get removed, but
it will take 2 hours.

quoted

If you do it this way, you break routing protocols when link is brought
down and back up.

The only addresses and routes flushed in this way should be ones that
aren't manually configured, i.e., the ones created by autoconf
(addrconf.c:2720 onwards). These won't be used by routing protocols,
except for link-local addresses. So I assume you're talking about
link-local here.

I posted a very similar patch recently:

http://marc.info/?l=linux-netdev&m=128415231909522&w=2

But the first response pointed out that I didn't test this with just a
simple link flap, in which case all the IPv6 addresses are deleted,
and all sessions using them die.  Not good.  This changes the current
behavior, and isn't what happens with IPv4 either.

Having these addresses restart DAD is probably about as much as we
can do I think, unless we add a per-device sysctl to remove the addresses
(which I think has been shot-down before).  Is this a mobile device that
is actually changing it's point of attachment?

-Brian