Re: [netlmm] Timestamp Option for Message Ordering

Sandesh,

The issue is bit more complex. Sending  a revocation message
is not suffcient. Note that the Seq Number scheme will work
much better in the presence of inter-MAG CT. Any case, you
can always write a I-D on other approaches for solving the
BU ordering issue and bring this to discussion. Also, please
see the (to be) WG draft on PMIP/MIP coexistence draft, it
addresses the related scenario.

Thanks
Sri

On Tue, 29 Jul 2008, Sandesh wrote:

> Hi All,
>
> I am proposing a solution for the problem which
> section '5.5 Timestamp Option for Message Ordering'
> of draft-ietf-netlmm-proxymip6-18.txt intends to solve.
> Please ignore this mail if this approach has been discussed earlier.
>
> IMO problem can be defined as following -
> ------------------------------------------
> When LMA has received two or more PBU message for binding lifetime extension
> from two or more MAGs (and has not received PBUs from with lifetime = 0
> indicating MN detachment from all except one) then (in the absence of sequence
> number and timestamp) how can it be find out which MAG the MN is
> actually connected to.
>
> SOLUTION
> ------------------------------------------
> In this solution a new trigger type in BRI (from LMA to MAG) is added which
> indicate 'PBU Registration Confusion'.
>
> MAG Procedures -
> MAG PROCEDURE 1. MAG retransmits PBU if matching PBA is not received before
>  retransmission timeout. If MN is attached to MAG it keeps on
> retransmitting PBU
>  until it receives matching PBA. If MN detaches from MAG it
> retransmits PBU with
>  lifetime = 0 a number of times (N).
> MAG PROCEDURE 2. MAG sends PBU again if it receives BRI (Trigger = PBU
> Registration Confusion).
>  And after that it does PBU retransmissions as per MAG PROCEDURE 1.
>
> LMA procedures -
> LMA CASE 1: LMA received two or more PBUs (with lifetime !=0) and it has not
> sent PBA to any of the MAGs.
> It does not send PBA to any MAG. Soon it will receive the PBUs
> with lifetime = 0 from MAGs from which MN has detached and PBU(lifetime !=0)
> retransmission from MAG to which MN is actually attached.
> MN is considered to be attached to a MAG if and only all MAGs except one sends
> PBUs(lifetime = 0) and that one MAG sends PBU (lifetime !=0).
> A max timer can be defined to declare that MN is not attached to the MAG if no
> PBUs are received from a MAG (which first sent PBU with lifetime !=0) for
> that max timer duration.
> After the decision has been taken about which MAG an MN is attached to PBAs
> (status =0) are sent to all the MAGs.
>
>
> LMA CASE 2: LMA received two or more PBUs (with lifetime !=0) and it has
> sent PBA (Status = 0) to one of the MAGs.
> LMA send BRI(Trigger = PBU Registration Confusion) to the MAG to which
> it has sent
> PBA (Status = 0). After that LMA follows the procedure defined in Case
>
> Sequence number in PBU can be considered per MAG and can be used to drop
> old/duplicate PBUs from the same MAG.
>
> Disadvantage of this approach is that it will take little longer to declare
> which MAG a MN is attached to.
>
> Advantages of this solution are -
> - MAG need not send timestamp to LMA in PBUs
> - MAG need not sync sequence number with other MAGs.
>
> Thanks and Regards,
> Sandesh
> _______________________________________________
> netlmm mailing list
> netlmm@ietf.org
> https://www.ietf.org/mailman/listinfo/netlmm
>
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