Matching Realm names only.

Hi. I'm setting up a LAC for L2TP tunneling users to a remote LNS. On the LAC side I want it to obtain the tunneling parameters only based on the realm. What would be the simplest way to setup FreeRADIUS to only match the realm and return tunneling attributes. If the realm is not configured, then reject the authentication ? Is it possible to match the Realm in the users file like: DEFAULT Realm == "dsl.myisp.com" Service-Type = Framed-User, Tunnel-Type = L2TP, Tunnel-Server-Endpoint = "X.X.X.X", Tunnel-Medium-Type = IP Doesn't seem to work, do I need to include Auth-Type or anything else ? Thanx Paul