This is a request for adoption of the long-discussed A-MPDU status
extension. I finally got around to implementing it for testing.

This proposal adds the following field, as also documented on
http://www.radiotap.org/suggested-fields/A-MPDU%20status

Bit Number: 20
Structure: u32 reference number,
           u16 flags,
           u8 delimiter CRC value,
           u8 reserved
Required Alignment: 4 bytes

The presence of this field indicates that the frame was received as part
of an a-MPDU.

The reference number is generated by the capture device and is the same
across each subframe of an A-MPDU. Since the capture device might be
capable of capturing multiple channels or data from multiple
(concurrent) captures could be merged, the reference number is not
guaranteed to be unique across different channels. As a result,
applications should use the channel information together with the
reference number to identify the subframes belonging to the same A-MPDU.

The following flags are defined:

0x0001: driver reports 0-length subframes
0x0002: frame is 0-length subframe (valid only if 0x0001 is set)
0x0004: last subframe is known (should be set for all subframes in an
        A-MPDU)
0x0008: this frame is the last subframe
0x0010: delimiter CRC error
0x0020: delimiter CRC value known: the delimiter CRC value field is
        valid
0xffc0: reserved

Within an A-MPDU, the subframe index can be determined by the
application so it is not included, but depending on the driver reporting
this may miss 0-length subframes.

--- end of description ---


I've attached patches against wireshark to parse and the Linux kernel
(the stack and the iwlwifi driver) to report this field.

Barring any objections, I will repost at the end of the month for and
make the wiki updates to adopt this proposal. At that time, I'll also
file a bug against wireshark to update, with this patch.

johannes