Subject: Re: [MOBILE-IP] [Fwd: Re: [MOBILE-IP] New version of "MobilitySup port in IPv6"draft]

From: "Hesham Soliman (EPA)" <[email-masked]>
Date: Sat, 4 Nov 2000 09:37:53 +1100

Hello Dave and Charlie,

On the topic of new version of MIPv6, I'd like to bring up
one possible improvement. DAD !

I think this has been discussed a lot, we talked about it
in Adelaide, Pittsburgh and now it's a hot topic
(as Charlie knows ) in the fast handoffs team.

I don't think DAD is only relevant for fast handoffs.
I believe it is also relevant to the current standard.
As said earlier, with DAD we could be looking at a
2 second delay for the handoff. Certainly unacceptable
for any type of service.

Perhaps we can make some exceptions / suggestions
in the draft to work around some of the strict requirements
in 2462. I realise that most ideas will not be able to provide
us with a fault proof situation, however to avoid
this significant delay maybe we can live with a very
small probability of collision that will be detected shortly
anyway.

So what I have in mind is very simple,

execute handoff,
Get a new COA and use it while doing DAD in parallel.

I certainly see the problems with that. But something needs
to be done. A 2 seconds delay is unacceptable for any service.

Regards
Hesham

---

From: Francis Dupont <[email-masked]>
Date: Sat, 4 Nov 2000 18:44:20 +0100

In your previous mail you wrote:

=> this issue really depends on the type of the links which
are used then PLEASE give the context to us!

=> I disagree! If it takes some seconds to be attached to the link then
DAD is no more an issue. And if you believe a 2 second delay is very
high then you should ask for fast boot for every devices (routers,
computers running fatware OSs, ...).

   execute handoff,

=> how the handoff is detected is very important: in many cases
you still use the old COA on the new link just because you don't
know it is a new one.

=> in the previous context to do DAD just detects the problem
which can't be avoid then it is reasonnable (or the whole case
is not).

=> a simple(r|st) solution is to use only point-to-point links
where IPv6CP (or a similar tool) will do the DAD for free. This is
why the context is important!

Regards

[email-masked]