Protocols And Standards; Wmm Configuration - HP a-msr Configuration Manual

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Table Of Contents

Table of Contents

U-APSD power-save mechanism

U-APSD improves the 802.1 1 APSD power saving mechanism. When associating clients with AC queues, you

can specify some AC queues as trigger-enabled, some AC queues as delivery-enabled, and the maximum

number of data packets that can be delivered after receiving a trigger packet. Both the trigger attribute and

the delivery attribute can be modified when flows are established using CAC. When a client sleeps, the

delivery-enabled AC queue packets destined for the client are buffered. The client must send a

trigger-enabled AC queue packet to get the buffered packets. After the AP receives the trigger packet,

packets in the transmit queue are sent. The number of sent packets depends on the agreement made when

the client was admitted. AC queues without the delivery attribute store and transmit packets as defined in the

802.1 1 protocol.

SVP

SVP can assign packets with the protocol ID 1 19 in the IP header to a specific AC queue. SVP stipulates that

random backoff is not performed for SVP packets. Therefore, you can set both ECWmin and ECWmax to 0

when there are only SVP packets in an AC queue.

ACK policy

WMM defines two ACK policies: Normal ACK and No ACK.

When the No ACK policy is used, the recipient does not acknowledge received packets during wireless

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packet exchange. This policy is suitable in the environment where communication quality is fine and

interference is weak. While the No ACK policy helps improve transmission efficiency, it can cause

increased packet loss when communication quality deteriorates. When this policy is used, a sender

does not retransmit packets that have not been received by the recipient.

When the Normal ACK policy is used, the recipient acknowledges each received unicast packet.

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