Your software release may not support all of the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Restrictions on Band Selection, 802.11 Bands, and Parameters
Band-selection enabled WLANs do not support time-sensitive applications like voice and video because of roaming delays.
Band selection can be used only with Cisco Aironet 1040, 1140, 1250, 1260, 3500, and the 3600 series access points.
Band selection operates only on access points that are connected to a controller. A FlexConnect access point without a controller connection does not perform band selection after a reboot.
The band-selection algorithm directs dual-band clients only from the 2.4-GHz radio to the 5-GHz radio of the same access point, and it only runs on an access point when both the 2.4-GHz and 5-GHz radios are up and running.
You can enable both band selection and aggressive load balancing on the controller. They run independently and do not impact one another.
It is not possible to enable or disable band selection and client load balancing globally through the controller GUI or CLI. You can, however, enable or disable band selection and client load balancing for a particular WLAN. Band selection and client load balancing are enabled globally by default.
Information About Configuring Band Selection, 802.11 Bands, and Parameters
Band Selection
Band selection enables client radios that are capable of dual-band (2.4- and 5-GHz) operation to move to a less congested 5-GHz access point. The 2.4-GHz band is often congested. Clients on this band typically experience interference from Bluetooth devices, microwave ovens, and cordless phones as well as co-channel interference from other access points because of the 802.11b/g limit of three nonoverlapping channels. To prevent these sources of interference and improve overall network performance, you can configure band selection on the switch.
Band selection is enabled globally by default.
Band selection works by regulating probe responses to clients. It makes 5-GHz channels more attractive to clients by delaying probe responses to clients on 2.4-GHz channels.
802.11 Bands
You can configure the 802.11b/g/n (2.4-GHz) and 802.11a/n (5-GHz) bands for the controller to comply with the regulatory requirements in your country. By default, both 802.11b/g/n and 802.11a/n are enabled.
When a controller is configured to allow only 802.11g traffic, 802.11b client devices are able to successfully connect to an access point but cannot pass traffic. When you configure the controller for 802.11g traffic only, you must mark 11g rates as mandatory.
802.11n
Parameter
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.
802.11h Parameter
802.11h informs client devices about channel changes and can limit the transmit power of those client devices.
You must disable the 802.11a band before configuring the 802.11a network parameters.
Step 3
ap dot11 24ghz shutdown
Example:
Switch(config)# ap dot11 24ghz shutdown
Disables the 802.11b band.
Note
You must disable the 802.11b band before configuring the 802.11b network parameters.
Step 4
ap dot11 {5ghz | 24ghz} beaconperiodtime_unit
Example:
Switch(config)# ap dot11 5ghz beaconperiod 500
Specifies the rate at which the SSID is broadcast by the access point.
The beacon interval is measured in time units (TUs). One TU is 1024 microseconds. You can configure the access point to send a beacon every 20 to 1000 milliseconds.
Step 5
ap dot11 {5ghz | 24ghz} fragmentationthreshold
Example:
Switch(config)# ap dot11 5ghz fragmentation 300
Specifies the size at which packets are fragmented.
The threshold is a value between 256 and 2346 bytes (inclusive). Specify a low number for areas where communication is poor or where there is a great deal of radio interference.
Step 6
ap dot11 {5ghz | 24ghz} dtpc
Example:
Switch(config)# ap dot11 5ghz dtpc
Switch(config)# no ap dot11 24ghz dtpc
Enables access points to advertise their channels and transmit the power levels in beacons, and probe responses.
The default value is enabled. Client devices using dynamic transmit power control (DTPC) receive the channel and power level information from the access points and adjust their settings automatically. For example, a client device used primarily in Japan could rely on DTPC to adjust its channel and power settings automatically when it travels to Italy and joins a network there.
Note
On access points that run Cisco IOS software, this feature is called world mode.
The no form of the command disables the 802.11a or 802.11b DTPC setting.
Step 7
wireless client association limitnumberintervalmilliseconds
Example:
Switch(config)# wireless client association limit 50 interval 1000
Specifies the maximum allowed clients that can be configured.
You can configure a maximum number of association request on a single access point slot at a given interval. The range of association limit that you can configure is from one through 100.
The association request limit interval is measured between 100 to 10000 milliseconds.
Specifies the rate at which data can be transmitted between the controller and the client.
disabled—Defines that the clients specify the data rates used for communication.
mandatory—Defines that the clients support this data rate in order to associate to an access point on the controller.
supported—Any associated clients that support this data rate may communicate with the access point using that rate. However, the clients are not required to be able to use this rate in order to associate.
rate—Specifies the rate at which data is transmitted. For the 802.11a and 802.11b bands, the data is transmitted at the rate of 1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36, 48, or 54 Mbps.
Step 9
no ap dot11 5ghz shutdown
Example:
Switch(config)# no ap dot11 5ghz shutdown
Enables the 802.11a band.
Note
The default value is enabled.
Step 10
no ap dot11 24ghz shutdown
Example:
Switch(config)# no ap dot11 24ghz shutdown
Enables the 802.11b band.
Note
The default value is enabled.
Step 11
ap dot11 24ghz dot11g
Example:
Switch(config)# ap dot11 24ghz dot11g
Enables or disables 802.11g network support.
The default value is enabled. You can use this command only if the 802.11b band is enabled. If you disable this feature, the 802.11b band is enabled without 802.11g support.
Step 12
end
Example:
Switch(config)# end
Returns to privileged EXEC mode.
Configuring the
802.11 Bands (GUI)
Step 1
Choose
Configuration > Wireless > 802.11a/n/ac > Network or
Configuration > Wireless > 802.11b/g/n > Network to open the Global Parameters
page.
Step 2
Select the
802.11a/n/ac (or
802.11b/g)
Network Status check box
to enable the 802.11a or 802.11b/g band. To disable the band, unselect the
check box. The default value is enabled. You can enable both the 802.11a and
802.11b/g bands.
Step 3
If you enabled the 802.11b/g band in
Step 2,
select the
802.11g Support check box
if you want to enable 802.11g network support. The default value is enabled. If
you disable this feature, the 802.11b band is enabled without 802.11g support.
Step 4
Specify the period at which the SSID is broadcast by the
access point by entering a value between 20 and 1000 milliseconds (inclusive)
in the Beacon Period text box. The default value is 100 milliseconds.
Note
The beacon period in
controllers is listed in terms of milliseconds. The beacon period can also be
measured in time units, where one time unit equals 1024 microseconds or 102.4
milliseconds. If a beacon interval is listed as 100 milliseconds in a
controller, it is only a rounded off value for 102.4 milliseconds. Due to
hardware limitation in certain radios, even though the beacon interval is, say
100 time units, it is adjusted to 102 time units, which roughly equals 104.448
milliseconds. When the beacon period is to be represented in terms of time
units, the value is adjusted to the nearest multiple of 17.
Step 5
Specify the size at which packets are fragmented by
entering a value between 256 and 2346 bytes (inclusive) in the Fragmentation
Threshold text box. Enter a low number for areas where communication is poor or
where there is a great deal of radio interference.
Step 6
Make access points advertise their channel and transmit
power level in beacons and probe responses for CCX clients. Select the
DTPC Support check box.
Otherwise, unselect this check box. The default value is enabled.
Client devices using dynamic transmit power
control (DTPC) receive the channel and power level information from the access
points and adjust their settings automatically. For example, a client device
used primarily in Japan could rely on DTPC to adjust its channel and power
settings automatically when it travels to Italy and joins a network there.
Note
On
access points that run Cisco IOS software, this feature is called
world mode.
Note
DTPC and 801.11h power
constraint cannot be enabled simultaneously.
Step 7
Specify the
maximum allowed clients by entering a value between 1 to 200 in the Maximum
Allowed Client text box. The default value is 200.
Step 8
Use the Data Rates options to specify the rates at which
data can be transmitted between the access point and the client. These data
rates are available:
Mandatory—Clients must support this data rate in order to
associate to an access point on the controller.
Supported—Any associated clients that support this data rate
may communicate with the access point using that rate. However, the clients are
not required to be able to use this rate in order to associate.
Disabled—The clients specify the data rates used for
communication.
The no form of the command disables the 802.11n support on the network.
Step 3
ap dot11 {5ghz | 24ghz} dot11n mcs txrtu
Example:
Switch(config)# ap dot11 5ghz dot11n mcs tx 20
Specifies the modulation and coding scheme (MCS) rates at which data can be transmitted between the access point and the client. You can set a value from 0 through 23 for the mcs tx parameter.
The no form of the command disables the MCS rates that is configured.
Switch(config)# ap dot11 5ghz dot11n a-mpdu tx priority all
Specifies the aggregation method used for 802.11n packets.
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). Both A-MPDU and A-MSDU are performed in the software.
You can specify the aggregation method for various types of traffic from the access point to the clients.
The following 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 100-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. You can configure priority levels so that the traffic uses either A-MPDU transmission or A-MSDU transmission.
When you use the ap command along with the other options, the traffic associated with that priority level uses A-MPDU transmission.
When you use the no ap command along with the other options, 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-MPDU is enabled for all priorities except 6 and 7.
Step 7
no ap dot11 {5ghz | 24ghz} shutdown
Example:
Switch(config)# no ap dot11 5ghz shutdown
Reenables the network.
Step 8
ap dot11 {5ghz | 24ghz} dot11n guard-interval {any | long}
Example:
Switch(config)# ap dot11 5ghz dot11n guard-interval long
Configures the guard interval for the network.
Step 9
ap dot11 {5ghz | 24ghz} dot11n rifs rx
Example:
Switch(config)# ap dot11 5ghz dot11n rifs rx
Configures the Reduced Interframe Space (RIFS) for the network.
Step 10
end
Example:
Switch(config)# end
Returns to privileged EXEC mode. Alternatively, you can also press Ctrl-Z to exit global configuration mode.
Configuring the
802.11n Parameters (GUI)
Step 1
Choose
Configuration > Wireless > 802.11a/n/ac or
802.11b/g/n > High Throughput (802.11n) to open the
802.11n/ac (5 GHz or 2.4 GHz) Throughput page.
Step 2
Select the
Enable
11n check box to enable 802.11n support on the network. The default
value is enabled.
Step 3
Select the check boxes of the desired rates to specify the
modulation and coding scheme (MCS) rates at which data can be transmitted
between the access point and the client. These data rates, which are calculated
for a 20-MHz channel width using a short guard interval, are available:
0 (7 Mbps)
1 (14 Mbps)
2 (21 Mbps)
3 (29 Mbps)
4 (43 Mbps)
5 (58 Mbps)
6 (65 Mbps)
7 (72 Mbps)
8 (14 Mbps)
9 (29 Mbps)
10 (43 Mbps)
11 (58 Mbps)
12 (87 Mbps)
13 (116 Mbps)
14 (130 Mbps)
15 (144 Mbps)
16 (22 Mbps)
17 (43 Mbps)
18 (65 Mbps)
19 (87 Mbps)
20 (130
Mbps)
21 (173
Mbps)
22 (195
Mbps)
23 (217
Mbps)
Any associated clients that
support the selected rates may communicate with the access point using those
rates. However, the clients are not required to be able to use this rate in
order to associate. The MCS settings determine the number of spatial streams,
the modulation, the coding rate, and the data rate values that are used.
Step 4
Click
Apply.
Step 5
Use the 802.11n data rates
that you configured by enabling WMM on the WLAN as follows:
Choose
WLANs to open the WLANs page.
Click the ID number of the
WLAN for which you want to configure WMM mode.
When the WLANs > Edit page
appears, choose the
QoS tab to open the WLANs > Edit (Qos) page.
From the WMM Policy drop-down
list, choose
Required or
Allowed to require or allow client devices to use
WMM. Devices that do not support WMM cannot join the WLAN.
If you
choose
Allowed, devices that cannot support WMM can join
the WLAN but will not benefit from the 802.11n rates.
Click
Apply.
Step 6
Click
Save
Configuration.
Note
To determine if an access
point supports 802.11n, look at the 11n Supported text box on either the
802.11a/n (or 802.11b/g/n)
Cisco APs > Configure page or the 802.11a/n (or 802.11b/g/n) AP Interfaces > Details page.
Configuring 802.11h Parameters (CLI)
SUMMARY STEPS
1.configureterminal
2.ap dot11 5ghz shutdown
3.{ap | no ap} dot11 5ghz channelswitch modeswitch_mode
4.ap dot11 5ghz power-constraintvalue
5.no ap dot11 5ghz shutdown
6.end
DETAILED STEPS
Command or Action
Purpose
Step 1
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 2
ap dot11 5ghz shutdown
Example:
Switch(config)# ap dot11 5ghz shutdown
Disables the 802.11a network.
Step 3
{ap | no ap} dot11 5ghz channelswitch modeswitch_mode
Example:
Switch(config)# ap dot11 5ghz channelswitch mode 0
Enables or disables the access point to announce when it is switching to a new channel.
You can enter a 0 or 1 for the channelswitch parameter to specify whether transmissions are restricted until the actual channel switch (0) or are not restricted (1). The default value is disabled.
Step 4
ap dot11 5ghz power-constraintvalue
Example:
Switch(config)# ap dot11 5ghz power-constraint 200
Configures the 802.11h power constraint value in a range from zero through 255.
The default value for the value parameter is 3 dB.
Step 5
no ap dot11 5ghz shutdown
Example:
Switch(config)# no ap dot11 5ghz shutdown
Reenables the 802.11a network.
Step 6
end
Example:
Switch(config)# end
Returns to privileged EXEC mode. Alternatively, you can also press Ctrl-Z to exit global configuration mode.
Configuring the
802.11h Parameters (GUI)
Step 1
Disable the 802.11 band as
follows:
Choose
Configuration > Wireless > 802.11a/n/ac
> Network to open the 802.11a/n/ac Global
Parameters page.
Unselect the
802.11a Network Status check box.
Click
Apply.
Step 2
Choose
Configuration > Wireless > 802.11a/n/ac
> DFS (802.11h) to open the 802.11h Global
Parameters page.
Step 3
In the Power
Constraint area, enter the local power constraint. The valid range is between 0
dBm and 30 dBm.
Step 4
In the Channel Switch Announcement area, enter the channel
switch announcement mode. You can enter a value of either 1 or 0.
Step 5
Click
Apply.
Step 6
Reenable the 802.11a band as
follows:
Choose
Wireless > 802.11a/n/ac > Network to open the
802.11a/n/ac Global Parameters page.
Select the
802.11a Network Status check box.
Click
Apply.
Step 7
Click
Save
Configuration.
Monitoring Configuration Settings for Band Selection, 802.11 Bands, and Parameters
Monitoring Configuration Settings Using Band Selection and 802.11 Bands Commands
This section describes the new commands for band selection and 802.11 bands.
The following commands can be used to monitor band selection, and 802.11 bands and parameters the switch.
Table 2 Monitoring Configuration Settings Using Band Selection and 802.11 Bands Commands
Command
Purpose
show ap dot11 5ghz network
Displays 802.11a bands network parameters, 802.11a operational rates, 802.11n MCS settings, and 802.11n status information.
show ap dot11 24ghz network
Displays 802.11b bands network parameters, 802.11b/g operational rates, 802.11n MCS settings, and 802.11n status information.
show wireless dot11h
Displays 802.11h configuration parameters.
show wireless band-select
Displays band select configuration settings.
Example: Viewing the Configuration Settings for 5-GHz Band
Switch# show wireless dot11h
Power Constraint: 0
Channel Switch: 0
Channel Switch Mode: 0
Example: Verifying the Band Selection Settings
Switch# show wireless band-select
Band Select Probe Response : per WLAN enabling
Cycle Count : 2
Cycle Threshold (millisec) : 200
Age Out Suppression (sec) : 20
Age Out Dual Band (sec) : 60
Client RSSI (dBm) : 80
Configuration Examples for Band Selection, 802.11 Bands, and Parameters
Examples: Band Selection Configuration
This example shows how to set the probe cycle count and time threshold for a new scanning cycle period for band select:
This example shows how to set the suppression expire to the band select:
Switch# configure terminalSwitch(config)# wireless client band-select expire suppression 100Switch(config)# end
This example shows how to set the dual band expire for the band select:
Switch# configure terminalSwitch(config)# wireless client band-select expire dual-band 100Switch(config)# end
This example shows how to set the client RSSI threshold for the band select:
Switch# configure terminalSwitch(config)# wireless client band-select client-rssi 40Switch(config)# end
This example shows how to configure band selection on specific WLANs:
Switch# configure terminalSwitch(config)# wlan wlan1 25 ssid12Switch(config-wlan)# band-selectSwitch(config)# end
Examples: 802.11 Bands Configuration
This example shows how to configure 802.11 bands using beacon interval, fragmentation, and dynamic transmit power control:
Switch# configure terminalSwitch(config)# ap dot11 5ghz shutdownSwitch(config)# ap dot11 24ghz shutdownSwitch(config)# ap dot11 5ghz beaconperiod 500Switch(config)# ap dot11 5ghz fragmentation 300Switch(config)# ap dot11 5ghz dtpcSwitch(config)# wireless client association limit 50 interval 1000Switch(config)# ap dot11 5ghz rate 36 mandatorySwitch(config)# no ap dot11 5ghz shutdownSwitch(config)# no ap dot11 24ghz shutdownSwitch(config)# ap dot11 24ghz dot11gSwitch(config)#end
Examples: 802.11n Configuration
This example shows how to configure 802.11n parameters for 5-GHz band using aggregation method:
Switch# configure terminalSwitch(config)# ap dot11 5ghz dot11nSwitch(config)# ap dot11 5ghz dot11n mcs tx 20Switch(config)# wlan wlan1 25 ssid12Switch(config-wlan)# wmm require\
Switch(config-wlan)# exitSwitch(config)# ap dot11 5ghz shutdownSwitch(config)# ap dot11 5ghz dot11n a-mpdu tx priority allSwitch(config)# no ap dot11 5ghz shutdownSwitch(config)#exit
This example shows how to configure the guard interval for 5-GHz band:
Switch# configure terminalSwitch(config)# ap dot11 5ghz dot11nSwitch(config)# ap dot11 5ghz dot11n mcs tx 20Switch(config)# wlan wlan1 25 ssid12Switch(config-wlan)# wmm require\
Switch(config-wlan)# exitSwitch(config)# no ap dot11 5ghz shutdownSwitch(config)# ap dot11 5ghz dot11n guard-interval longSwitch(config)#end
This example shows how to configure the RIFS for 5-GHz band:
Switch# configure terminalSwitch(config)# ap dot11 5ghz dot11nSwitch(config)# ap dot11 5ghz dot11n mcs tx 20Switch(config)# wlan wlan1 25 ssid12Switch(config-wlan)# wmm require\
Switch(config-wlan)# exitSwitch(config)# ap dot11 5ghz shutdownSwitch(config)# ap dot11 5ghz dot11n rifs rxSwitch(config)#end
Examples: 802.11h Configuration
This example shows how to configure the access point to announce when it is switching to a new channel using restriction transmission:
Switch# configure terminalSwitch(config)# ap dot11 5ghz shutdownSwitch(config)# ap dot11 5ghz channelswitch mode 0Switch(config)# no ap dot11 5ghz shutdownSwitch(config)#end
This example shows how to configure the 802.11h power constraint for 5-GHz band:
Switch# configure terminalSwitch(config)# ap dot11 5ghz shutdownSwitch(config)# ap dot11 5ghz power-constraint 200Switch(config)# no ap dot11 5ghz shutdownSwitch(config)#end
Additional References for 802.11 Parameters and Band Selection
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