[MEXT] New RFC3775bis issue "BU de-registration race condition"?

["Kilian Weniger" <Kilian.Weniger at eu.panasonic.com>]

Hi all,

I think there is a possible race condition issue in RFC3775, which
should be considered for RFC3775bis.

The scenario is as follows: A MN returns home and sends a BU
de-registration. Once the HA receives the de-registration, it deletes
the BCE for the MN according to RFC3775. Now assume that just before
returning home, the MN has sent a BU (either refresh BU or BU with new
CoA due to handover) and that the BU is delayed and is received by the
HA after the BU de-registration. 

Since the HA has just deleted the MN's BCE due to the received BU
de-registration, the HA would accept the delayed BU without SN check and
create a new BCE with a CoA pertaining to the previous location of the
MN. This results in wrong forwarding state in the HA and hence packet
loss for the MN till the MN sends a new BU (next handover of the MN or
the lifetime of the BCE expires).

A simple mitigation for this problem could be that the HA keeps some BCE
information (at least HoA and SN) for some time after receiving a BU
de-registration. This would enable the HA to identify a delayed BU as a
delayed one based on the SN.

Comments?

BR,

Kilian

--------------------------------------------
Dr. Kilian Weniger
Panasonic R&D Center Germany
Monzastr. 4c, 63225 Langen, Germany
phone:  +49 (0)6103 766 137
fax:    +49 (0)6103 766 166
e-mail: kilian.weniger at eu.panasonic.com
--------------------------------------------


Panasonic R&D Center Germany GmbH
63225 Langen, Hessen, Germany
Reg: AG Offenbach (Hessen) HRB 33974
Managing Director: Thomas Micke


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