Subject: [mobile-ip] Re: closing issue 48, identifying link changes and prev-coa

From: Samita Chakrabarti <[email-masked]>
Date: Thu, 25 Jul 2002 18:50:08 -0700 (PDT)

Hi Jari,

I am catching up with emails after a long vacation, sorry for the
delay in replying. Has this issue been closed already ?

Here is what I think:

> We also discussed whether it makes sense to keep the previous coa 
functionality in the
> draft at all, and the application of SEND techniques in this space. We also 
noted that
> we don't enough experience to say exactly how security policies can be 
configured for the
> prev coa forwarding to work, and we are not sure it is practical to configure 
per MN SAs
> on the routers on the places you might be moving in.
> 

I agree with this. In terms of initial deployment, I believe, it's not very
practical idea considering the security association aspects of MN and the
temporary HAs on the previously visited link.

In order to simplify the base MIPv6 protocol, could we move this item to the
appendix section ? When we gain more experience, we can either drop this
item or develop a separate draft on this mechanism. Your proposal to deal
with default router change in the link sounds fine to me. But, the whole thing
can move to the appendix section for simplicity, IMHO.

Thanks,
-Samita

> I have a primary proposal on how to go forward. This is based on the 
observation that
> the original situation isn't very typical, so we shouldn't try to optimize it. 
It is
> sufficient to ensure that nothing horrible happens. So, we don't care even if 
the forwarding
> from previous coa would fail in this situation, or if some unnessary tunneling 
would take
> place. As long as the current coa works well and nothing breaks in the old 
coa, we are happy.
> Forwarding from previous coa should of course work in the usual case when you 
actually move to
> another link.
> 
> The proposal is that we allow MNs to request forwarding from previous CoA.
> We do not require them to be aware that they might possibly be on the same
> link due to one of the routers no longer being a default router. What happens
> then is that forwarding-from-previous-coa is requested. We require the 'D'
> and 'L' bits to be set in such BUs. This leads the HA to run DAD, which should
> fail as the link local address is still in use on the same physical link.
> Then, no forwarding will be done. (But this is fine, as the packets will
> normally come to the link anyway.)
> 
> Does this work for everyone? (A possible backup proposal:
> drop this functionality and deal with it in another spec.)
> 
> Jari
>

---

From: Jari Arkko <[email-masked]>
Date: Fri, 26 Jul 2002 15:26:18 +0300

> delay in replying. Has this issue been closed already ?

I'm not really sure. There's been many people who want the prev-coa
functionality moved elsewhere. In Yokohama we decided to move this
discussion to the list...

Jari