The AIR-ANT2524DW-RS antenna includes circuitry to enable self identification of the antenna by the Cisco Catalyst 91xx Series access points. The self identifying function is indicated by a purple band on the antenna. Ensure this antenna is connected to Port A on the AP, which is also designated by purple text around the RP-TNC connector. This antenna has a built-in EEPROM that can be read by the AP to automatically configure the antenna type and gain in the Wireless LAN Controller.