Description—You have configured a single AD FS 2.0 authentication server and you have attempted to use it for trunk authentication in more than one trunk and you receive the following message "The AD FS 2.0 authentication server 'authentication_server' is used in more than one trunk: [trunk_list]. Configure Forefront UAG to use the AD FS 2.0 authentication server in one trunk only."

Cause—An AD FS 2.0 authentication server can be used in one trunk only.

Solution—If you require more than one trunk to use federated authentication, you must configure additional AD FS 2.0 servers, each with a new public host name and Federation Service, after which you can use the new AD FS 2.0 server for trunk authentication. For more information, see Deploying Federation Servers.