FMIPv6 : Triggering of tunnel establishment

Hi,

Reading the fmipv6 draft 06, one change I noticed is the triggering of HI /
HACK exchange
between ARs. Draft 06 requires HI / HACK exchange to be initiated after
receiving an
FBU from MN. Though the reason for this is clear, I do have some doubts
about it:

   1. If stateful address configuration is used at NAR, until NAR allocates
NCoA and
         sends it in HACK message, the PAR is not aware of the NCoA. In
such a scenario,
      PAR would not be in a position to send NCoA in PrRtAdv, and
subsequent FBU /
      FNA sending from MN would also be done without MN knowing the NCoA.

   2. For packet buffering at PARs, the draft specifies "When the PAR
receives an FBU,
      it MUST send a HI message to the NAR. Upon receiving a corresponding
HACK
      message, the PAR MUST send FBACK to the MN. Until the HACK is
received,
      the PAR MAY buffer any packets arriving for the MN."

      In this case, if MN sends FBU after attaching to the new link then
      there would be
      some packet loss which can be avoided if AR starts buffering on
      receipt of RtSolPr.

   3. For buffering at NAR, the draft specifies "The New Access Router MUST
NOT
      tunnel packets from the MN with PCoA as source IP address destined
for arbitrary
      correspondent nodes to PAR until a HI message is received, and the
NAR MAY
      buffer any such packets."

      What would be the trigger for NAR to start buffering?

Regards,
Suvidh