Subject: [mobile-ip] processing of the home address option

From: Henrik Petander <[email-masked]>
Date: Fri, 24 Aug 2001 13:01:34 +0300 (EEST)

Hi all,

I sent email about the same subject to the list some weeks ago, but 
I guess it got lost in the mail storm which took place right before the
IETF meeting. 

Section 8.1 in MIPv6 draft 14 specifies that the home address option
should be processed only after all the other options in the same
destination option header are processed. In practice, this requirement
makes the receiver keep state between different options. I wonder, whether
the requirement is really worth the extra complexity it creates in all
IPv6 nodes.

If the ordering is required, it would IMHO be better to make the ordering
the responsibility of MN, which adds the options, i.e. "The home address
option MUST be added as the last destination option to the destination
option header ...". This would simplify the CN and would increase the
complexity of MN only marginally. 

Regards,

Henrik Petander

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		Henrik Petander 		
		Helsinki University of Technology,	
		GO/Core Project 
		[email-masked]
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From: "Peter Grimstrup (TED)" <[email-masked]>
Date: Wed, 29 Aug 2001 11:58:08 +0200

Hi Henrik,

Comments inline

Regards
Peter

> complexity of MN only marginally.

The only problem being if some future option(s) must be *last* as well.
In that case, splitting into 2 (or more) destination option headers may be the
solution, is that feasible?

-- 
Peter Grimstrup          Systems Developer
Ericsson Telebit A/S     tel: +45 89 38 52 75
Skanderborgvej 232       fax: +45 89 38 51 01
DK 8260 Viby J, Denmark  e-mail: [email-masked]

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From: "Charles E. Perkins" <[email-masked]>
Date: Wed, 29 Aug 2001 07:52:37 -0700

Hello Henrik

> the requirement is really worth the extra complexity it creates in all

The intention was to make sure that processing the home address
option would cause the mobile node's home address to be delivered
to the higher level protocols at the correspondent node, while still
allowing the care-of address to be visible at the IP layer.  The
restriction about when the processing occurs should probably be
removed, because it does not matter how an implementation ensures
the correct property of the home address option (as long as it does
ensure it).  Currently, the care-of address doesn't serve any
purpose past this point, and would not have to be maintained by
the implementation after processing at the network layer.

Regards,
Charlie P.

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From: Lars Henrik Petander <[email-masked]>
Date: Thu, 30 Aug 2001 10:27:30 +0300 (EET DST)

Hello Charlie,

Thanks for the clarification. 

On Wed, 29 Aug 2001, Charles E. Perkins wrote:
> allowing the care-of address to be visible at the IP layer. 

Our implementation processes the destination options in order, but
maintains a pointer to the home address option now containing the CoA, so
we did not understand the purpose of the requirement.

> The
> ensure it).  

I agree with you on this.

Henrik