How to force a specific WLAN-802.11x-Tx-Rate for Aironet AP 12xx?

[paul.schwann]

Hi there,

for testing purposes, I would like to force an Aironet 1230 AP to SEND

with a specific WLAN data rate (say 48 MBit/s). Unfortunately, I am

unable to do that.

A Linksys AP for example is able to to do it. Its webinterface has an

attribute "Tx Rate" where I can select the data rate for Data-Packets.

Any ideas? Thanks a lot!

Regards,

Paul

[Rob Huffman]

Hi Paul,

Perhaps this is what you are looking for;

Configuring Radio Data Rates

You use the data rate settings to choose the data rates the wireless device uses for data transmission. The rates are expressed in megabits per second. The wireless device always attempts to transmit at the highest data rate set to Basic, also called Require on the browser-based interface. If there are obstacles or interference, the wireless device steps down to the highest rate that allows data transmission. You can set each data rate to one of three states:

Basic (the GUI labels Basic rates as Required)?Allows transmission at this rate for all packets, both unicast and multicast. At least one of the wireless device's data rates must be set to Basic.

Enabled The wireless device transmits only unicast packets at this rate; multicast packets are sent at one of the data rates set to Basic.

Disabled The wireless device does not transmit data at this rate.

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Note At least one data rate must be set to basic.

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You can use the Data Rate settings to set an access point to serve client devices operating at specific data rates. For example, to set the 2.4-GHz radio for 11 megabits per second (Mbps) service only, set the 11-Mbps rate to Basic and set the other data rates to Disabled. To set the wireless device to serve only client devices operating at 1 and 2 Mbps, set 1 and 2 to Basic and set the rest of the data rates to Disabled. To set the 2.4-GHz, 802.11g radio to serve only 802.11g client devices, set any Orthogonal Frequency Division Multiplexing (OFDM) data rate (6, 9, 12, 18, 24, 36, 48, 54) to Basic. To set the 5-GHz radio for 54 Mbps service only, set the 54-Mbps rate to Basic and set the other data rates to Disabled.

You can configure the wireless device to set the data rates automatically to optimize either the range or the throughput. When you enter range for the data rate setting, the wireless device sets the 1 Mbps rate to basic and the other rates to enabled. When you enter throughput for the data rate setting, the wireless device sets all four data rates to basic.

From this doc;

http://www.cisco.com/en/US/products/hw/wireless/ps430/products_configuration_guide_chapter09186a0080606d4a.html#wp1101903

Hope this helps!

Rob

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[paul.schwann]

Hi Rob,

thanks a lot for your detailed explanation! By setting the proper basic (required) and extended (enabled) rates, I can force the transmit rate used (more or less, I am aware about things linke rate fallback and thelike).

Unfortunately, changing the rate settings causes the cisco to dissaciate all stations. That behavior forces the full procedure of assoc, auth, WPA and EAP handshaking (which takes 30 or more seconds).

Do you know a way of manipulating the rate settings w/o a disassociation of the station?

Thanks again!

Regards,

Paul