Mobility Express
Controller Redundancy for Failover
In a Cisco Mobility Express network, not all APs have the capability to work as a primary AP. See Supported Cisco Access Points to know which AP models are capable of working as a primary AP.
In order to have Cisco Mobility Express controller redundancy to enable a failover, your network must have two or more active APs with primary AP capability. In
the event of a failover, one of these other APs will automatically be elected as a primary. The newly elected primary will
have the same IP and configuration as the original primary. From an administrator perspective, there will be no difference
between the original primary and the newly elected primary in case of a failover.
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Clients that connect to the primary AP will lose connectivity during a failover.
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Mobility Express Controller Forced Failover
In a Cisco Mobility Express network, not all APs have the capability to work as a primary AP. See Supported Cisco Access Points to know which AP models are capable of working as a primary AP.
You can manually force any AP, that has the capability to work as a primary AP, to become the primary AP. This forced failover
of the primary AP to another primary-capable AP of your choice can be performed both using the GUI and the CLI.
To perform a forced failover using the GUI:
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Choose Wireless Settings > Access Points.
The Access Points Administration window is displayed.
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Click the Edit icon adjacent to the AP you want to set as primary.
The Edit window with the General tab is displayed.
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Under the General tab, next to the Operating Mode field, click Make me Controller.
Note |
For a primary AP, the Operating Mode field shows AP & Controller. For other associated APs, this field shows AP Only. The Make Me Controller button is available only for subordinate APs that are capable of participating in the primary election process.
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To perform a forced failover using CLI, use the following command: config ap next-preferred-master cisco-ap-name forced-failover
When you force the failover of the primary to an AP of your choice, using the GUI or CLI methods, the current primary AP reboots
while the new AP takesover as the controller, with the IP address and configuration as the previous primary. The previous
primary, after rebooting, comes back online and joins the new primary AP as a subordinate AP.
Note |
Like any failover, this forced failover causes some downtime in the Cisco Mobility Express network. During this downtime, clients associated to APs that have the standalone feature enabled will not face any disruption
in service. Clients of APs that do not have the standalone functionality enabled will be affected.
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Primary AP Election Process
In a Cisco Mobility Express network, when the primary AP shuts down, one of the other primary-capable APs in this deployment is automatically designated
as the primary AP. The automatic selection of the primary AP among the Cisco Mobility Express-capable APs is as per an internal automatic primary election process. This process is used to both detect the failure of
the primary AP and to designate the new primary AP among the eligible APs. This process is based on Virtual Router Redundancy
Protocol (VRRP) that algorithmically determines the next primary AP, based on the following parameters listed in the order
of descending precedence:
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The AP configured as VRRP primary, using the VRRP command config ap next-preferred-master on the controller's CLI.
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The AP with the least load in terms of the number of associated clients associated.
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Among APs with a similar client load, the AP with the lowest MAC address.
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