• I've found some tid-bits of errata (nothing huge), but noteworthy nonetheless.

    Page 5-12, next to last paragraph says:

    Figure 5-12 shows an example of traffic flows with U-APSD. In this case, the trigger for retrieving traffic is the client sending traffic to the AP. The AP, when acknowledging the frame, tells the client that data is queued for it, and that is should stay on. The AP then sends data to the client typically as a TXOP burst where only the first frame has the EDCF access delay. All subsequent frames are then sent directly after the acknowledgment frame.

    The ACK sent by the QoS AP does not notify the QoS STA that data is buffered. That is done through the TIM in the Beacon.

    It's not, "typically as a TXOP burst", but rather it's always that way. The last sentence is confusing. What it should state is that the burst is a series of acknowledged data frames separated by SIFS that, as a group, take no longer than the maximum allowed time of a TXOP.

    For more information, check out the Wi-Fi Alliance's document called, "WMM Power Save for Mobile and Portable Wi-Fi CERTIFIED Devices"

    Page 5-19 says:

    If 7920 AP CAC limit is to be supported, the number 3 QBSS IE is sent in the beacons and probe responses for border gateway (bg) radios.

    "border gateway (bg) radios"? say what?

    Page 5-21 says:

    For example, when WMM classified traffic is sent by a WLAN client, it has an 802.1p classification in its frame. The AP needs to translate this classification into a DSCP value for the LWAPP packet carrying the frame to ensure that the packet is treated with the appropriate priority on its way to the WLC. A similar process needs to occur on the WLC for LWAPP packets going to the AP.

    Uh, I think not. The 802.11 frame carries user priority (UP) values which are directly mapped to 802.1D priority values. 802.1p classification values ARE NOT carried in the 802.11 frame. Why do they keep using 802.1p anyway? 802.1D specifies the values, and 802.1Q gives us a place in the Ethernet frame to put the values. oy.


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