Cisco 8821 Manual page 96

Once the desired access points have been configured successfully to enable Wireless Domain Services, then all access points
including those serving as WDS servers need to be configured to be able to authenticate to the WDS servers.
Enable Participate in SWAN Infrastructure.
If using a single WDS server, then can specify the IP address of the WDS server; otherwise enable Auto Discovery.
Enter the Username and Password to be used to authenticate to the WDS server.
Cisco Wireless IP Phone 8821 and 8821-EX Wireless LAN Deployment Guide
96