As of LCOS 9.00, the configuration of the WLAN physical parameters on WLCs and also on APs now includes the option of allowing the AP to select a suitable 2.4-/5-GHz mode.
- 2.4-GHz mode / 5-GHz modeHere you specify the wireless standard(s) that the physical WLAN interface provides to the WLAN clients.
In the 2.4-GHz and the 5-GHz frequency bands, there are several different wireless standards that an AP can use for transmission. In the 2.5-GHz frequency band, these were to date the standards IEEE 802.11b, IEEE 802.11g and IEEE 802.11n; in the 5-GHz frequency band, the standards are IEEE 802.11a, IEEE 802.11n and IEEE 802.11ac. Depending on the device type and selected frequency band, you have the option of operating an AP in just one particular mode or one of the compatibility modes.
Important: Please observe that WLAN clients supporting only a slower standard may not be able to associate with the WLAN if the value for the mode is set too high. However, compatibility is always achieved at the expense of performance. It is therefore recommended to allow only those modes of operation that are absolutely necessary for the wireless LAN clients in use.For example, if there are only 802.11n-enabled devices in your WLAN, it is recommended to select greenfield mode (802.11n only): By doing this you prevent login of slower clients which would otherwise act as a brake on the network. By selecting a compatibility mode, you are able to achieve the best possible data rates without excluding slower WLAN clients (e.g., for 2.4 GHz 802.11g/b/n (mixed); for 5 GHz 802.11a/n (mixed)). In compatibility mode, a physical WLAN interface works according to the fastest standard, but reverts to a slower standard if a slower WLAN client logs on to the network. When using 802.11b, you can select whether the physical WLAN interface should exclusively support 11-Mbps mode or also the older 2-Mbps mode (... (2-Mbps-compatible)). For APs operating according to the 802.11g standard you can optionally increase the data transfer speeds up to 108Mbps. In what is referred to as Turbo mode, an AP simultaneously uses two neighboring free channels for the radio transmission. With an AP in the 108Mbps Turbo mode, the only WLAN clients that can establish a connection to this AP are those also operating with the 108Mbpss Turbo mode.Note: Turbo mode is associated with the 802.11g standard, although it was never officially adopted by the IEEE. The technology represents the proprietary extensions of various chipset manufacturers who also market this technology under the name "802.11g+" or "802.11g++". Turbo mode is therefore exclusively available on APs with pure 802.11g hardware.If you leave the selection of the 2.5/5-GHz mode up to the device with the Automatic setting, the selection of the best mode depends on the frequency band in use and the capabilities of the device hardware:
- In the 2.4-GHz mode, the automatic setting results in either 802.11g/b/n (mixed) or 802.11 g/b (mixed).
- In the 5-GHz mode, the automatic setting results in either 802.11ac/a/n (mixed), 802.11 a/n (mixed), or 54Mbps mode.