Subject: [MEXT] Issue #7 - 3775bis

From: "Vijay Devarapalli" <[email-masked]>
Date: Wed, 4 Mar 2009 19:00:44 -0500

On issue #7 (http://tools.ietf.org/wg/mext/trac/ticket/7),
draft-ietf-mip6-nemo-v4traversal has already been updated to say 

   When the home agent receives the encapsulated binding update, it
   compares the IPv4 address of the source address field in the IPv4
   header with the IPv4 address included in the IPv4 care-of address
   option.  If the two addresses match, no NAT device was in the path.

So this fixes part of the issue.

Regarding the text in section 9.5.1 in RFC 3775, based on the earlier
discussions, we should replace the following

   o  If the Lifetime specified in the Binding Update is zero or the
      specified care-of address matches the home address for the
      binding, then this is a request to delete the cached binding for
      the home address. 

with

   o  If the Lifetime specified in the Binding Update is zero, then 
      this is a request to delete the cached binding for the home 
      address. 

Vijay

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From: "Charles E. Perkins" <[email-masked]>
Date: Fri, 06 Mar 2009 15:49:41 -0800

Hello Vijay,

O.K.  Thanks for the text.  I have made the requested change.

With this change, it was the overall plan to be able to close
issue #7. If anyone does not agree, please let me know.

What should the home agent do if it receives a packet in
which the care-of address matches the home address, but
the lifetime is not zero?

Regards,
Charlie P.

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From: "Vijay Devarapalli" <[email-masked]>
Date: Fri, 6 Mar 2009 18:55:41 -0500

Hi Charlie, 

> the lifetime is not zero?

This is an error. If the mobile node is attached to a visited link, it
shouldn't be sending a packet to the home agent with the source address
set to the home address. The only time, the home address would match the
care-of address is when the mobile node is sending a binding update from
the home link. As far as RFC 3775 is concerned, the mobile node cannot
have a binding when it is attached to the home link. Therefore the
lifetime is going to be 0 anyway. 

The Multiple CoA draft extends Mobile IPv6 by allowing a mobile node to
have a valid binding even when attached to the home link. But this is
indicated by a new flag in the binding update. This is already described
in detail in the Multiple CoA draft.

Vijay