Subject: Re: [mobile-ip] ISSUE: Design team recommendation: New recommendation on piggybacking

From: [email-masked]
Date: Thu, 28 Feb 2002 14:28:23 -0500

> > I must have been asleep when somone proposed creating an IPPROTO_MIPV6
> > (or whatever) type, and removing them from a Destination Options header.
> > Is this really what the DT meant? 
> 
> Yes.

It's all coming back to me... you're talking about a new destination
option header that would be placed either in front or in back of the
existing DO header.  So should the HAO also be placed in this new
header since it is for mobility as well?

-Brian

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From: "Jari Arkko" <[email-masked]>
Date: Thu, 28 Feb 2002 21:41:48 +0200

> header since it is for mobility as well?

No, HAO needs to be a DO since it goes with the data packets.
HAO is piggybacked ;-)

The new protocol would only be for MIPv6 control messages, such as
RR messages or the BU contained within them.

Jari

---

From: Vijay Devarapalli <[email-masked]>
Date: Thu, 28 Feb 2002 16:05:26 -0800

hi all,

> RR messages or the BU contained within them.

I just tried putting together the format of the new extension
header. looks very much like the destination options header.
called it the mobility options header :) the format of the 
options is different from the IPv6 destination options. the 
difference is in the length field. instead of octets, it is 
in terms of 4 octets.

Vijay

1. New Extension Header Order

           IPv6 header
           Hop-by-Hop Options header
           Destination Options header (1)
           Routing header
           Destination Options header (2)
           Fragment header
           Authentication header
           Encapsulating Security Payload header
           Mobility Options header
           Destination Options header (3)
           upper-layer header

	   (1) for options to be processed by the first destination
               that appears in the IPv6 Destination Address field
               plus subsequent destinations listed in the Routing
               header.

           (2) contains only Mobile IPv6 Home Address Option (HAO)

           (3) for options to be processed only by the final
               destination of the packet.

2. Mobility options header

   The Mobility Options header is identified by a Next Header value of 
   62 (??) in the immediately preceding header, and has the following 
   format:

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Next Header  |  Hdr Ext Len  |                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
    |                                                               |
    .                                                               .
    .                            Options                            .
    .                                                               .
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Next Header          8-bit selector.  Identifies the type of header
                        immediately following the Mobile IPv6 options
                        header.  Uses the same values as the IPv4
                        Protocol field [RFC-1700 et seq.].

   Hdr Ext Len          8-bit unsigned integer.  Length of the
                        Mobility Options header in 8-octet units, not
                        including the first 8 octets.

   Options              Variable-length field, of length such that the
                        complete Mobility Options header is an
                        integer multiple of 8 octets long.  Contains one
                        or  more TLV-encoded options, as described in
                        section 3.

3. Mobility Options

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
      |  Option Type  |  Opt Data Len |  Option Data
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -

      Option Type          8-bit identifier of the type of option.

      Opt Data Len         8-bit unsigned integer.  Length of the Option
                           Data field of this option, in 4 octets, not 
                           including the first 4 octets.

      Option Data          Variable-length field.  Option-Type-specific
                           data.

4. Possible Mobility Options

Binding Update - remains the same, except for the length field
Binding Acknowledgement - remains the same, except for the length field
Binding Request - remains the same, except for the length field
Return Routability (possibly multiple options)
PAD1
PADn

(note: The length field in the Mobililty Options is in terms of 4 
octets thereby allowing upto 1028 bytes in each option. This should 
be more than enough to carry any CGA information. There has been 
atleast one complaint that the limit of 256 bytes in Destination 
Options is not good for CGA)