This section provides instructions for managing 802.11n devices such as the Cisco Aironet 1140 and 3600 Series Access Points on your network. The 802.11n devices support the 2.4- and 5-GHz bands and offer high-throughput data rates.

The 802.11n high-throughput rates are available on all 802.11n access points for WLANs using WMM with no Layer 2 encryption or with WPA2/AES encryption enabled.

Note	Some Cisco 802.11n APs may intermittently emit incorrect beacon frames, which can trigger false wIPS alarms. We recommend that you ignore these alarms. The issue is observed in the following Cisco 802.11n APs: 1140, 1250, 2600, 3500, and 3600.

• Enable 802.11n support on the network by entering this command:

  config {802.11a | 802.11b} 11nsupport {enable | disable}

• Specify the modulation and coding scheme (MCS) rates at which data can be transmitted between the access point and the client by entering this command:

  config {802.11a | 802.11b} 11nsupport mcs tx {0-15} {enable | disable}

• Use the 802.11n data rates that you configured by enabling WMM on the WLAN as follows:

  config wlan wmm {allow | disable | require} wlan_id

  The require parameter requires client devices to use WMM. Devices that do not support WMM cannot join the WLAN.

  If set to allow, devices that cannot support WMM can join the WLAN but do not benefit from 802.11n rates.

• Specify the aggregation method used for 802.11n packets as follows:

  1. Disable the network by entering this command:

     config {802.11a | 802.11b} disable network

  2. Specify the aggregation method entering this command:

     config {802.11a | 802.11b} 11nsupport {a-mpdu | a-msdu} tx priority {0-7 | all} {enable | disable}

     Aggregation is the process of grouping packet data frames together rather than transmitting them separately. Two aggregation methods are available: Aggregated MAC Protocol Data Unit (A-MPDU) and Aggregated MAC Service Data Unit (A-MSDU). A-MSDU is performed in hardware and therefore is the default method.

     You can specify the aggregation method for various types of traffic from the access point to the clients. This table defines the priority levels (0-7) assigned per traffic type.

     Table 1 Traffic Type Priority Levels

     User Priority	Traffic Type
     0	Best effort
     1	Background
     2	Spare
     3	Excellent effort
     4	Controlled load
     5	Video, less than 100-ms latency and jitter
     6	Voice, less than 10-ms latency and jitter
     7	Network control

     You can configure each priority level independently, or you can use the all parameter to configure all of the priority levels at once. When you use the enable command, the traffic associated with that priority level uses A-MPDU transmission. When you use the disable command, the traffic associated with that priority level uses A-MSDU transmission. Configure the priority levels to match the aggregation method used by the clients. By default, A-MPDU is enabled for priority level 0, 4 and 5 and the rest are disabled. By default, A-MSDU is enabled for all priorities except 6 and 7.

  3. Reenable the network by entering this command:

     config {802.11a | 802.11b} enable network

• Configure the 802.11n-5 GHz A-MPDU transmit aggregation scheduler by entering this command:

  config 802.11{a | b} 11nsupport a-mpdu tx scheduler {enable | disable | timeout rt timeout-value}

  The timeout value is in milliseconds. The valid range is between 1 millisecond to 1000 milliseconds.

• Configure the guard interval for the network by entering this command: config 802.11{a | b} 11nsupport guard_interval {any | long}

• Configure the Reduced Interframe Space (RIFS) for the network by entering this command:

  config 802.11{a | b} 11nsupport rifs rx {enable | disable}

• Save your changes by entering this command: save config

• View the configuration settings for the 802.11 networks by entering this command:

  show {802.11a | 802.11b}

802.11h informs client devices about channel changes and can limit the transmit power of those client devices.