Subject: [mobile-ip] New BETH Draft

From: [email-masked]
Date: Mon, 8 Oct 2001 20:46:03 +0200

Hello,

I have a Question in "Two Party Handover" from BETH.

What happen when the oAR or the nAR don't receive a L2 Trigger before MN
move to nAR?
What happen with the Tunnel-End?

Bye
Jens

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From: James Kempf <[email-masked]>
Date: Fri, 12 Oct 2001 15:28:06 -0700 (PDT)

>What happen with the Tunnel-End?

In general,  BETH depends on having accurate and timely information
on handover sequencing. The draft identifies which L2 trigger
events are required, and which are just helpful in achieving optimizations
such as limiting tunnel lifetime.

If an L2 Source Trigger or L2 Target Trigger is missing, then there may not be 
enough time prior to the L2 handover event to actually achieve loss free
handover. In this situation, the establishment of the tunnel would
depend on trigger information on the nAR, presumably only on
L2 Link Up. The oAR and nAR must exchange HRqst/HRply while the
MN is waiting. The result would be a gap in L3 level coverage which
must be covered by buffering.

If the the L2 Link Down trigger on oAR is lacking, the oAR can use the 
sending/receipt of the HRply to initiate the tunnel, but there may then be a 
period of time in which packets to the MN are delievered to the
MN through both the oAR and nAR ("bicasting"), even if the MN is
not physically on the nAR L2 yet.

Neither case is optimal, but both can be covered by particular
smoothing techniques.

		jak