Association fails if WDS and infrastructure Access Points are in different subnets
The WDS and the infrastructure APs communicate over a multicast protocol called WLAN Context Control Protocol (WLCCP). These multicast messages cannot be routed, so a WDS and the associated infrastructure APs must be in the same IP subnet and on the same LAN segment. Between the WDS and the WLSE, WLCCP uses TCP and User Datagram Protocol (UDP) on port 2887. When the WDS and WLSE are on different subnets, a protocol like Network Address Translation (NAT) cannot translate the packets.
An AP configured as the WDS device supports up to 60 participating APs. An Integrated Services Router (ISR) configured as the WDS devices supports up to 100 participating APs. And a WLSM-equipped switch supports up to 600 participating APs and up to 240 mobility groups. A single AP supports up to 16 mobility groups.
Note: Cisco recommends that the infrastructure APs run the same version of IOS as the WDS device. If you use an older version of IOS, the APs might fail to authenticate to the WDS device. In addition, Cisco recommends that you use the latest version of the IOS. You can find the latest version of IOS in the Wireless downloads page.