Mobility Express is based on the Flex architecture and supports central authentication and local switching of data traffic. Meaning, in a Mobility Express deployment, all clients are centrally authenticated and data traffic is locally switched by the access point including primary AP which also service clients.
By deploying multiple ME APs, you can ensure redundancy. If the master AP fails, another ME AP will take over as the master, and all subordinate APs will connect to the new master ME AP.
These Access Points should have AP Image type as MOBILITY EXPRESS IMAGE and AP Configuration as MOBILITY EXPRESS CAPABLE. In an event of a failure of primary AP, another Cisco 1800 series AP is elected as a primary automatically. The newly elected primary AP has the same IP and configuration as the original primary AP.
With regards to AP performance - I don't think it will effect client wireless performance when AP running ME image as it's not handling client traffic. If there are more than 50 Access Points in a Mobility Express network, the Master AP(running the Wireless LAN controller function) can service a maximum of 20 clients. This limit only applies to Master AP and not any other Access Point in the Mobility Express network.
Jagan Chowdam
/**Pls rate useful responses**/
