Subject: [mobile-ip] Issues leading to the design of the proactive mobility draft

From: Theo Pagtzis <[email-masked]>
Date: Thu, 12 Jul 2001 12:12:37 -0700

Hi Pat/all,

 The issues that led to the draft specification proposed on proactive
mobility
(draft-pagtzis-mobileip-proactivev6-00.txt/.ps)  was driven by a number
of factors:

1) to effect seamlessness the MN must not wait until it reaches the
overlap area between  two coverage areas before it initiates generation
of IP state, what we call roaming state. For irregular mobility patterns
and high speed movement this is not going to be sufficient for
elimination of disruption in IP 'connectivity'

1.a) since we would not like the MN to wait till the overlap area
between cells is reached, we have considered that a 1-level lookahead of
IP connectivity state should be sufficient for 360 degrees of movement.
That is proactive allocation of roaming state.

However how can you say what is around you in terms of routing entities
that can provide you with this roaming context state? Thus we reached
issue (2)

2) effecting a proactive mobility approach requires that the approach
makes two distinctions

     a mobility neighbourhood - a set of coverage areas. Basically what
the MN 'feels' _first_ when roving around.
     a routing neighbourhood - a set of routing entities. Basically what
the MN 'sees' _apparently first_ when getting IP connectivity.

2.a) This requires that _no_ assumptions are made about specific routing
neighbourhood topologies over a mobility neighbourhood otherwise. This
why we have considered spanning tree topologies as a generich topology
vehicle.

2.b) the need to establish a mapping between the mobility neighbourhood
and the routing neighbourhood so that roaming state is producable
proactively.

2.c) how could we take as example the generation of roaming state
proactively for the generation of other context state
classes/ontologies. I.e. what if it is not just roaming state that we
want to know ahead of time at candidate points of attachement.

3) if roaming state is generate proactively how to proceed in mapping it
in an abstract routing identifier that can determine the existence of
the MN in the mobility neighbourhood of its current point of attachment.
In other words, how to map a plurality of IP (soft) CoA behind an
routing identifier during the period of handoff for 360 degrees.
Multicast was considered as the level of indirection. Attention must be
paid to the fact that such mapping is transparent to the peer entities
of the MN, i.e. it is effected at the point of attachement of the MN.

4) to eliminate cell bouncing between two or more coverage areas.
Movement paths for an MN depending on the mean of transport used is not
usually correlated to the placement pattern of AP. Hence cell-bouncing
is expected to be the first candidate of problems in seamless mobility.

5) How to manage multicast group membership indirectly with respect to
mobility management issues concerning enabling of roaming state behind
this abstract (CoA) routing identifier for a single MN.

6) How to manage the refresh of the roaming state for a single MN so
that it stays valid throughout its mobility pattern within a mobility
neighbourhood.

7) Neighbour discovery issues for indirect mobility management.

These are the issues we have considered as essential in any proactive
mobility design, and thus have driven the specification of this draft.
Based on these issues we would like to hear what the community feels on
the approaches followed.

Theo

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From: James Kempf <[email-masked]>
Date: Thu, 12 Jul 2001 12:20:25 -0700 (PDT)

Hi Theo,

Thanx for the updates in the thought behind your draft.

The draft is somewhat volumnous and will take some time to assess, but it
looks quite interesting.

		jak

>X-mProtect: Thu, 12 Jul 2001 12:12:38 -0700 Nokia Silicon Valley Messaging 
Protection
>Date: Thu, 12 Jul 2001 12:12:37 -0700
>From: Theo Pagtzis <[email-masked]>
>To: [email-masked], [email-masked], [email-masked], 
[email-masked]
>Subject: [mobile-ip] Issues leading to the design of the proactive mobility 
draft