Radio Tuning

When you set up your APs, you might encounter interference, the grouping of several APs in one location. You might also need to change the configured AP channel. The sections that follow show how to manage these settings through both the web browser interface and the CLI.


In this chapter, settings are configured on an Aironet 1130AG AP. Your AP might differ, although this device uses both 2.4- and 5-GHz radios, so you can make the settings on your own devices.

Determining Optimal Channel and Frequency

There are 11 channels available on the 2.4-GHz radio and 23 channels available on the 5-GHz radio. The best settings for the 2.4-GHz radio are channels 1, 6, and 11. This is because these channels do not overlap and provide the best performance. Because of this, you can configure three APs to work in the same environment and not interfere with each other. However, keep the APs at least 5 feet apart. Even on different channels, the broadcasting APs can still interfere with one another.

Bandwidth for the 5-GHz radio, on the other hand, overlaps slightly. You can lessen the impact of this overlap, however, by selecting channels that are not adjacent to each other for neighboring APs.

Tuning to the Optimal Channel and Frequency

When first powered up, Cisco APs scan the airwaves and use the Least Congested Frequency setting for channel selection. That is, the AP listens to the airwaves, and then selects the channel with the least amount of traffic on it. To configure the radio to your own settings, select the Settings tab from the web interface, as shown in Figure 11-2.

Figure 11-2. The Settings Tab Is Home to Various Radio Settings

Scroll farther down this page and you can find the settings for channel and frequency settings as illustrated in Figure 11-3. Select the channels and frequencies you wish from the Least Congested Channel Search list, and then click Apply at the bottom of the screen.

Figure 11-3. Setting Channel and Frequency Values on the Settings Tab

Table 11-4 lists and describes the commands to configure the channel and frequency settings if you elect to use the CLI instead of the web interface.

Table 11-4. Configuring Channels



configure terminal

Enters global configuration mode.

interface dot11radio {0 | 1}

Enters configuration mode for the radio interface. The 2.4-GHz radio is radio 0, and the 5-GHz radio is radio 1.

channel frequency | least-congested

Establishes the default channel. If you enter least-congested, you select the least congested channel available.

The following are the channels and frequencies for the 2.4-GHz radio:

Channel 12412

Channel 22417

Channel 32422


Channel 42427

Channel 52432

Channel 62437

Channel 72442

Channel 82447

Channel 92452

Channel 102457

Channel 112462

Channel 122467 (EMEA and Japan only)

Channel 132472 (EMEA and Japan only)

Channel 142484 (Japan only and only for 802.11b)

The following are the channels and frequencies for the 5-GHz radio:

Channel 345170 (Japan only)

Channel 365180

Channel 385190 (Japan only)

Channel 405200

Channel 425210 (Japan only)

Channel 445220

Channel 465230 (Japan only)

Channel 485240

Channel 525260

Channel 565280

Channel 605300

Channel 645320

Channel 1005500

Channel 1045520

Channel 1085540

Channel 1125560

Channel 1165580

Channel 1205600

Channel 1245620

Channel 1285640


Channel 1325660

Channel 1365680

Channel 1405700

Channel 1495745

Channel 1535765

Channel 1575785

Channel 1615805


Returns to privileged EXEC mode.


The WLSE can also set channels. Also, a controller-based solution can automatically assign channels. Again, WLSE was examined in Chapter 10, "CiscoWorks Wireless LAN Management Solution Engine."

Cisco 802.11 Wireless Networking Quick Reference
Cisco 802.11 Wireless Networking Quick Reference
ISBN: 158705227X
EAN: 2147483647
Year: 2005
Pages: 126

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