[Mip4] New revision for rfc3344bis; UDP inconsistency and candidate solution

["Charles E. Perkins" <charles.perkins at nokia.com>]

Hello folks,

I have a revision of rfc3344bis all ready to go.  I am
thinking about making one further small modification,
according to the following discussion.

Some time ago, I received an e-mail about some
inconsistency in the language used by rfc3344bis
when describing the handling of the Source Port field
of Registration Reply messages by the home agent.

The confusion arises because of the following conflicting
elements of the specification:
- The UDP destination port of the Registration Request
  is set to 434
- The home agent is mandated to copy the value of the
  destination port of the Registration Request message
  into the UDP source port field of the Registration Reply
- That source port field is described as "variable".

As pointed out, copying the value of the destination
port into the source port should be identically the same
as setting the source port value to 434.  So, the value
of the field cannot be described as "variable" as things
now stand.

It could well be that there are implementations of
foreign agents and mobile nodes that check to make
sure that the value is correct according to the above
specified procedure, so I am reluctant to change the
actual behavior of the home agent.

I propose the following text changes:

(A) In section "3.4. Registration Reply", change

>    UDP fields:
>
>        Source Port           <variable>

to be:

   UDP fields:

       Source Port           434

This conforms also with language used in
section 3.7.2.3.


(B). In section "3.8.3.1. IP/UDP Fields", change:

>       UDP Source Port
>                Copied from the UDP Destination Port of the Registration
>                Request.

to be:

         UDP Source Port
                Set to the value 434

=============================================

I expect to send out the new revision of rfc3344bis with
these changes in the next day or two.  This revision is
otherwise the same as should have already have been
posted to the Internet Draft before the recent IETF
meeting.

Regards,
Charlie P.

PS. Thanks to Hrishikesh Kulkarni for pointing out the
       discrepancy on this matter.

--
Please address return e-mail to charles.perkins at nokia.com


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