Capwap Mailing List: Agreed upon text for issue 217: What is frame format when WTP encrypts/decrypts

[Pat Calhoun (pacalhou) (pcalhoun]

All,

As previously stated, we had agreement on the list to include the
following
language, but the change was not made in the -02 binding draft. I am
once more
sending to the list the change that is being made to -03.

2.1.1.  Split MAC
[...]
   The WTP SHALL include the IEEE 802.11 MAC header contents in all
   frames transmitted to the AC.

<replaced text>
   When 802.11 encryption/decryption is performed at the WTP, the WTP
   MUST decrypt the uplink frames, MUST set the Protected Frame field to
   0, and MUST make the frame format consistent with that of an
   unprotected 802.11 frame prior to transmitting the frames to the AC.
   The fields added to an 802.11 protected frame, i.e., IV/EIV, MIC,and
   ICV , MUST be stripped off prior to transmission from the WTP to AC.
   For downlink frames, the Protected Frame field MUST be set to 0 by
   the AC as the frame being sent is unencrypted.  The WTP MUST apply
   the required protection policy for the WLAN, and set the Protected
   Frame field on transmission over the air.  The Protected Frame field
   always needs to accurately indicate the status of the 802.11 frame
   that is carrying it.
</replaced text>

   When 802.11 encryption/decryption is performed at the AC,the WTP
   SHALL NOT decrypt the uplink frames prior to transmitting the frames
   to the AC.  The AC and WTP SHALL populate the IEEE 802.11 MAC header
   fields as described in Figure 3.

Pat Calhoun
CTO, Wireless Networking Business Unit
Cisco Systems