Subject: RE: [mobile-ip] Handover Smoothing - What to Do?

From: "Casati, Alessio (Alessio)" <[email-masked]>
Date: Sat, 4 Aug 2001 17:46:46 +0100

*My conclusion is that any use of bicasting needs to be strictly
*limited in time, with well-defined start and stop times.  The
*ability to define these start and stop times is crucial, and yet
*whenever it is possible to do so, it might equally well be possible
*to design protocol so that unicast packets go where they ought to go.

Another point one could consider is that the assumption we would be
better off with bicasting than with any other solution may not
pass some checkpoints, like fast movement thru a sequence > 2
access points. Would this require ">2-casting"? also, bicasting is
implicitly
assuming some movement prediction, to be any different than 
non bicasting based solutions. Clearly, many times tricasting
or quadricasting or ... would be required, when multiple handoff candidates
need to be considered.

Reality is that a mobile node has (at most) one point of attachment 
at a time and other possible points of reachability of the MN
are only point of collection of packets 
that were "in flight" before the MN hooked up to the current point 
of attachment ("Before" is defined w.r.t the time when a HA or a CN 
is updated about the current point of attachment to the internet). 
These point of collection of packets may be
kind enough to forward packets to the current point of attachment 
(and they can be kind only if somebody, most likely upon request 
of the MN, kindly asked to forward packets to some appropriate 
next-hop).

This is to me a model that meets the "sufficient" engineering criterion,
so I'm hesitant to encourage bi(?)casting based solutions.

alessio