Cisco Cisco 5520 Wireless Controller 기술 참조

WCP—Wireless Control Protocol

WiSM-2—Wireless Service Module-2

Access Point State Full Switchover where CAPWAP state for each AP is 
maintained on Active and Standby WLC and CAPWAP state is retained after 
switchover to Standby WLC. AP need not go through CAPWAP discovery and 
join process after failover.

This is the WLC which is currently active in HA pair and taking care of the 
wireless network. APs establish single CAPWAP tunnel with Active WLC.

Wireless Client State Full Switchover where client state is also maintained on 
Active and Standby WLC and wireless clients are not de-authenticated after 
switchover. Will be supported in future release.

Standby WLC in HA setup sends keep-alive packets on redundancy port to check 
the health of active WLC. With no acknowledgment of three keep-alive packets 
from active WLC, standby declares active as dead and takes over the network. 

When Standby WLC cannot communicate to gateway or cannot discover peer 
WLC i.e. active WLC via redundant port it goes in Maintenance mode. In this 
mode WLC cannot communicate to infra network and will not participate in HA 
process. Because WLC in maintenance mode does not participate in HA process 
it need to be manually rebooted to bring it out of maintenance mode and make 
participate in HA process again. 

Unique MAC address shared between peers in HA setup. This mac address 
should be used to form a mobility pair between HA setup and another WLCs in 
HA setup or with independent controllers. By default active WLC mac address 
is shared as mobility mac address but mobility mac can also be manually 
configured on active WLC using a CLI, which will be shared between peers in 
HA setup.

AP SSO is box-to-box redundancy i.e. 1:1 so both the WLCs (Active and 
Standby) in HA setup are peer to each other.