Hi P.K,
not too sure that you will be able to dynamicaly manage bandwidth via radius. The only way i have heard of doing it is by using the Cisco BBSM (now end of life) which supported bandwith management. You could of place the users dynamically into a VALN which was managed by the BBSM (like for visitor access).
If you find a different soltuion post back
Cheers
mark
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