Subject: [Monami6] Adding lifetime to the BID option

From: Heikki Mahkonen <[email-masked]>
Date: Fri, 17 Mar 2006 15:46:56 +0200

Hi,

I have read the MCoA draft (draft-wakikawa-mobileip-multiplecoa-05.txt)
and what I think is that it should take into an acount that mobile nodes
might have a need for a differnet binding lifetimes for different CoAs.

When multiple CoAs are registered with a single BU each of these
registrations are now made with the same binding lifetime (in the BU
option) even though some of the CoAs might have shorter lifetimes and
some might have longer lifetimes.

The RFC 3775 states that the binding lifetime in home registration must
be equal or less than the remaining valid lifetime of the HoA or/and CoA
(RFC 3775 11.7.1) and the binding lifetime in the CN registration must
be less than or equal to the remaining home registration lifetime or/and
the remaining valid lifetime of the CoA (RFC 3775 11.7.2).

What this means is that now all the bindings will have the lifetime
which is derived based on the shortest lifetime of any CoA or the HoA.
However, there might be some CoAs which could be registered with a
longer lifetimes to reduce signaling.

As a solution I propose that the BID option specified in the MCoA draft
should include a binding lifetime field for corresponding CoA. This
would enable MNs to make home and CN registration for each of the CoAs
with specific binding lifetime.

As a side effect this solution would also enable MNs to de-register old
CoAs and register new CoAs with a single BU message. The de-registration
could be done by setting the binding lifetime of the BID option to zero
when de-registering a CoA and setting it to valid binding lifetime when
registering a CoA.

In addition, to the changes suggested by Martti Kuparinen to the BID
option I think that the binding lifetime field could also be added into
the BID option.

                             1                   2                   3
         0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                                        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                        |   Type = TBD  |     Length    |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |     Binding Unique ID (BID)   |  Priority     |B|  Reserved   |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |          Lifetime             |           Reserved            |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |         Home Nonce Index      |     Care-of Nonce Index       |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                                                               |
        +                                                               +
        |                         Authenticator                         |
        +                                                               +
        |                                                               |
        +---------------------------------------------------------------+

Lifetime:

     16-bit unsigned integer. The number of time units remaining before

     the binding MUST be considered expired. A value of zero
     indicates that the Binding Cache entry for the mobile node MUST be
     deleted. One time unit is 4 seconds. Overrides the lifetime value

     specified in the Binding Update message header.

Best regards,

Heikki Mahkonen

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