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

["Ahmad Muhanna" <amuhanna at nortel.com>]

Hi Kilian,

I see this a very very rare race condition that possibly may never
happen.
Both BU are sent by the mobile node and the mobile node, before it sent
the de-registration BU, it is for sure aware that there is an
outstanding BU that has not been acknowledged yet.

So I am wondering why we need to consider this case?

Regards,
Ahmad
 

> -----Original Message-----
> From: mext-bounces at ietf.org [mailto:mext-bounces at ietf.org] On 
> Behalf Of Kilian Weniger
> Sent: Tuesday, October 14, 2008 3:59 AM
> To: mext at ietf.org
> Subject: [MEXT] New RFC3775bis issue "BU de-registration race 
> condition"?
> 
> 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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