Re: [STDS-802-11] CID 1109 from 11mc LB193
--- This message came from the IEEE 802.11 Working Group Reflector ---
The same sequence number is used in all the gcr retransmission modes. For example when using gcr block ack the retransmissions will have the same sn as the original transmission.
You are right that gcr-sp is a special case because these frames might be transmitted before the "legacy" transmission. A sta receiving a gcr-sp knows to discard the legacy transmission.
Alex
--- Original Message ---
From: "Hamilton, Mark" <Mark.Hamilton@xxxxxxxxxxxxxxx>
Sent: 20 April 2013 17:32
To: STDS-802-11@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11] CID 1109 from 11mc LB193
--- This message came from the IEEE 802.11 Working Group Reflector ---
Henry,
That sort of logic was our conclusion in Orlando discussions as well. However, note the unsolicited retry (non GCR-SP mode) uses the same sequence number as was used for the original transmission (despite the MSDU having been reframed into a different MPDU). So, we definitely have "special rules" at play. The question to the GCR experts is whether this was intended to extend to the PN.
My personal opinion is that it can/should not cover the PN. The sequence number 'intentional replay' provides enough information to GCR-aware receivers to correctly understand the frames being sent, and to not confuse non-GCR-aware STAs. There is no reason to apply special rules to the PN, which would require 'pushing higher up the stack' special-case GCR-awareness.
Mark
-----Original Message-----
From: *** IEEE stds-802-11 List *** [mailto:STDS-802-11@xxxxxxxx] On Behalf Of Henry Ptasinski
Sent: Friday, April 19, 2013 5:58 PM
To: STDS-802-11@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11] CID 1109 from 11mc LB193
--- This message came from the IEEE 802.11 Working Group Reflector ---
If I understand clause 10.24.16.3.5 correctly, the payload of the retransmission may be different than the payload of the original frame (specifically, by the addition of A-MSDU framing in some cases). If that's true, the "retransmission" would need to use a different PN to avoid encrypting two different payloads with the same PN.
---
Henry Ptasinski
henry@xxxxxxxxxx
On 04/19/2013 01:47 PM, Dan Harkins wrote:
> --- This message came from the IEEE 802.11 Working Group Reflector ---
>
> Hello,
>
> CID 1109 from LB193 concerns CCMP protection of multicast
> frames that get concealed with GCR, specifically is a different
> PN used when retransmitting using GCR? The 11mc group discussed
> this in Orlando and decided the discussion should go to the list.
> And here it is, on the list.
>
> The assumption in Orlando was that a different PN will be used
> for the retransmitted MSDU because it will be concealed inside a
> different MPDU. But that assumption was made by people (like
> me) who are not familiar with GCR and therefore the assumption
> might very well be wrong.
>
> Can anyone who is familiar with GCR please comment? If anyone
> has implemented GCR, please say what you did so this CID is
> resolved properly.
>
> thank you,
>
> Dan.
>
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