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Re: [MEXT] New RFC3775bis issue "BU de-registration race condition"?
Hi Hesham,
> => Right, so according to that and my previous email, the
> race condition
> can't happen because the BU sent from the old foreign network
> will have an
> old seq no.
But how can the HA know that the seqno in the received BU is old? In
this specific scenario the HA has deleted the MN's BCE containing the
current seqno before receiving the delayed BU (upon receiving the BU
de-registration).
Or do you refer to the IPsec ESP seqno? IPsec ESP wouldn't discard a BU
with old ESP seqno, since ESP doesn't provide correct ordering of
messages (just anti-replay service).
BR,
Kilian
> >> -----Original Message-----
> >> From: Conny Larsson [mailto:conny.larsson at ericsson.com]
> >> Sent: Dienstag, 14. Oktober 2008 12:18
> >> To: Kilian Weniger
> >> Cc: mext at ietf.org
> >> Subject: Re: [MEXT] New RFC3775bis issue "BU de-registration
> >> race condition"?
> >>
> >> Hi Kilian,
> >>
> >> I had a quick look in RFC3775 and I agree that it's not clear
> >> and most
> >> likely some clarifications would be good. However, I thought
> >> about the
> >> SA established between the MN and the HA. When the BCE is
> >> deleted does
> >> the SA go away as well? In case of static SAs I guess they
> >> remain but in
> >> case of dynamic SA establishment they could have been
> deleted and in
> >> that case the delayed BU would not be accepted and an ICMP
> >> message would
> >> be sent back to the MN. I need to look a bit more into RFC3775 to
> >> understand it better ...
> >>
> >> Regards
> >> Conny
> >>
> >> Kilian Weniger wrote:
> >>> 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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> >>>
> >>
> >>
> >>
> >
> >
> > Panasonic R&D Center Germany GmbH
> > 63225 Langen, Hessen, Germany
> > Reg: AG Offenbach (Hessen) HRB 33974
> > Managing Director: Thomas Micke
> >
> >
> > _______________________________________________
> > MEXT mailing list
> > MEXT at ietf.org
> > https://www.ietf.org/mailman/listinfo/mext
>
>
>
>
Panasonic R&D Center Germany GmbH
63225 Langen, Hessen, Germany
Reg: AG Offenbach (Hessen) HRB 33974
Managing Director: Thomas Micke
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