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Cisco IOS Software Configuration Guide for Cisco Aironet Access Points
OL-29225-01
Chapter6 Configuring Radio Settings
Configuring Radio Data Rates
to be made based on resources available to the wireless project, type of traffic the users will be passing,
service level desired, and as always, the quality of the RF environment.When you enter throughput for
the data rate setting, the wireless device sets all four data rates to basic.
Note When a wireless network has a mixed environment of 802.11b clients and 802.11g clients, make sure
that data rates 1, 2, 5.5, and 11 Mbps are set to required (basic) and that all other data rates are set to
enable. The 802.11b adapters do not recognize the 54 Mbps data rate and do not operate if data rates
higher than 11Mbps are set to require on the connecting access point.
Access Points Send Multicast and Management Frames at Highest Basic Rate
Access points running recent Cisco IOS versions are transmitting multicast and management frames at
the highest configured basic rate, and is a situation that could causes reliability problems.
Access points running LWAPP or autonomous IOS should transmit multicast and management frames at
the lowest configured basic rate. This is necessary in order to provide for good coverage at the cell's
edge, especially for unacknowledged multicast transmissions where multicast wireless transmissions
may fail to be received.
Since multicast frames are not retransmitted at the MAC layer, stations at the edge of the cell may fail
to receive them successfully. If reliable reception is a goal, then multicasts should be transmitted at a
low data rate. If support for high data rate multicasts is required, then it may be useful to shrink the cell
size and to disable all lower data rates.
Depending on your specific requirements, you can take the following action:
•If you need to transmit the multicast data with the greatest reliability and if there is no need for great
multicast bandwidth, then configure a single basic rate, one that is low enough to reach the edges of
the wireless cells.
•If you need to transmit the multicast data at a certain data rate in order to achieve a certain
throughput, then configure that rate as the highest basic rate. You can also set a lower basic rate for
coverage of non-multicast clients.
Beginning in privileged EXEC mode, follow these steps to configure the radio data rates:
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface dot11radio {0 | 1} Enter interface configuration mode for the radio interface. The
2.4-GHz radio and 2.4-GHz N radio is radio 0, and the 5-GHz
radio and 5-GHz N radios radio 1.