Subject: [Mip6] Question on return routability ?

From: Mikko Hautala <[email-masked]>
Date: Fri, 21 Oct 2005 15:36:20 +0300

Hi,

I have a simple question on the return routability procedure of
MIPv6 route optimization:

Is the return routability procedure needed every time a MN conducts a
MIPv6 handover ?

I've been reading the MIPv6 RFC and the route optimization design 
background, but
I haven't been able to figure it out explicitly.

I'm about 90% sure, that it is needed, because the care-of-address is 
used when calculating MAC.
Thus every time a MN moves, it must at least update the care-of token 
with COTI/COT messages...

Regards,
Mikko Hautala

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From: Zhen Zhen <[email-masked]>
Date: Fri, 21 Oct 2005 10:58:11 -0300 (ADT)

Yes, it's true if the handover is across domains.

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From: Jari Arkko <[email-masked]>
Date: Fri, 21 Oct 2005 18:34:47 +0300

Mikko,

The worst case is that you need to run whole procedure for each
movement that changes your care-of address (there are also other
types of movements).

Then there are cases allowed by RFC 3775 where an old (prior
to movement) home test can be used after a movement.

Further optimizations are discussed in various drafts. E.g,
draft-arkko-mipshop-cba-cga discusses a method that reduces
the need to run home tests and makes care-of tests parallel
with actual data flow.

Hope this helps,

--Jari

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From: Francis Dupont <[email-masked]>
Date: Fri, 21 Oct 2005 18:41:26 +0200

In your previous mail you wrote:

   
=> yes, the care-of address check doesn't work for a new address so
something (else than sending a BU) has to be done each time.

=> good hint!

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