Data Rates

The speed at which data is transferred between devices in a network is called data rate. It is measured in megabits per second. You can configure the data rate settings of an access point to choose the data rate it uses for transmission.

For 802.11b, the data rates are 1, 2, 5.5, and 11 Mbps. For 802.11g, the data rates are 6, 9, 12, 18, 24, 36, 48, and 54 Mbps.

You can set each data rate to one of three states:

• Supported—The access point transmits only unicast packets at this rate.

• Mandatory—The access point transmits at mandatory rate for management, broadcast frames and data frames. Multicast packets are sent at one of the mandatory data rates. Also, mandatory data rate is set per site.

• Disabled—The access point does not transmit data at this rate.

The access point always attempts to transmit at the highest enabled data rate. If the access point cannot transmit at that rate due to interference or another reason, it tries to transmit using the next highest data rate that is enabled. On most access points, multicast and broadcast packets are transmitted at the lowest basic rate. However, some access point models transmit multicast and broadcast packets at the highest enabled data rate. For more information, refer to Multicast Transmissions. Management packets, which can be transmitted only at basic rate, are usually transmitted at the highest basic rate.