how many clients use TCP Radius

What clients actually use Radius over TCP? I can't find anything out there that's widely deployed and can query a Radius server over TCP. E.g. the Cisco documentation for routers, etc. seems to indicate that they only do UDP. The reason why I'm asking - I'm looking into setting up authentication for a variety of clients, with Radius used as a transport protocol, and I'm wondering if it's worth the trouble to even think about enabling TCP, or promising I could offer TCP. Thanks, -- Florin Andrei http://florin.myip.org/