You should check out Cisco ISE. It is radius and many other things. Cisco ISE is not easy to learn and its also not easy to try. I suggest a cisco lab offering to learn the product.
Also check out Piotr (Piotr Kaluzny) class on ISE over at ine.com http://www.ine.com. Piotr class is pretty good and he made me laugh at least once. Its not too deep and not too shallow. It covers most of the functions of ISE. Check out the INE.com t-shirts also.
Unfortunate for you learning ISE, there are no learning labs for ISE. Cisco please fix this. Its not always easy to get vmware running ISE. People need a good way to learn it. The cisco learning labs link is below. The ccna labs are pretty good.
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