Channel selection involves the manual assignment of RF channels to the radios on the Meraki APs. Optimizing channel assignments reduces channel interference and channel utilization, thereby improving overall network performance and increasing the network’s client capacity. Meraki's AutoRF algorithm makes this process hands off by using the Meraki cloud to determine the optimal channel configuration for a network by periodically measuring the global network performance and issuing new channel assignments to APs. However, sometimes administrators may wish to fine-tune channels by modifying placements themselves.
Channel selection is configured under the Configure tab on the Radio Settings page. Two views are available for viewing channel selection and manually assigning channels; a 'map' view and a 'list' view.
AP placements are shown on Google maps and custom floorplans (if they have been uploaded). On the maps view, APs are shown with coverage circles roughly denoting their coverage area based on their transmit power (note that these coverage circles are approximate, and do not take into account interference or obstruction by walls or certain types of building materials). By selecting an AP, it is possible to see settings to manually adjust the channel and power settings on both of its radios (2.4 GHz and 5 GHz). By default, APs will broadcast their 'auto' settings for both channel and power; in this case, the administrator allows the Meraki cloud to use AutoRF to automatically assign the optimal channels to the radios. However, the administrator can manually configure the channels used by the Meraki APs on the 2.4 GHz and 5 GHz bands.
Note: When selecting an AP, only the coverage circles of APs on overlapping channels will be shown.
This view presents a more classic list view of all APs in the network, and can be toggled between the 2.4 and 5 GHz bands. By clicking on an AP in the list, the channel and power settings options are shown and can be manually configured.
Changing channel assignments can cause noticeable network downtime. The administrator can configure the Meraki cloud to automatically reassign channels in the wireless network during periods of inactivity (when the channel reassignment would cause the least amount of disruption). Or, the administrator can perform the cloud-calculated channel assignments on demand.
The list of available channels that can be assigned to radios is populated based on which country the APs are deployed in. The “Country” setting is configured automatically based on (a) what country the AP was shipped to and (b) what country the AP was plugged into (using IP-lookups from a geo-location database. This is to help administrators comply with region-specific wireless regulations. If there is a conflict in the ship-to country and actual country of where the AP is plugged in, the AP will default to a "world-wide safe mode" where it will broadcast on a safe channel and power setting that is globally neutral; in this case, the UI will display a warning, and the administrator can contact Meraki Support for assistance.
When automatic channel selection is configured, "channel spreading” is automatically configured, which allows Meraki APs to operate on different channels. Channel spreading selects channels that minimize RF utilization and interference in the network, thereby maximizing overall network performance and client capacity (i.e., the number of wireless clients that can connect to the network).
Channel spreading is ideal for environments in which a high number of clients could saturate a single channel. For instance, in an auditorium with hundreds of wireless clients and numerous APs broadcasting in the same space, channel spreading should be enabled.
It is also possible to force the Meraki cloud to calculate the optimal channel placements for an AP at any given time by clicking the 'update auto channels' button; please note that this will disconnect clients as the APs gather interference from their environment.
Administrators have the option of having all APs in the network set at 100% transmit power or allowing the Meraki cloud to determine the best power settings for optimal performance. In cases where APs are deployed with high density and significant overlap in coverage, the Meraki cloud may determine that interference could be minimized by a reduction in transmit power. In this situation, if an AP were to go down resulting in a gap in coverage, the adjacent AP power levels would then be automatically increased to compensate. Administrators can select full transmit power or automated transmit power selection on the Radio Settings Page.
This AP list view offers a summary of the current channel plan in the network, and also provides information on non-Meraki or “rogue” APs that were detected on each channel during the last network scan performed. This information includes the maximum signal strength (RSSI) seen on the AP's channel from its nearby Meraki neighbor, as well as the maximum RSSI seen on the same channel from a non-Meraki rogue. This information can be used to more effectively assign channels manually when necessary.