I have the following strange behavior:
my WLCs connects to RADIUS server using the IP address of a dynamic interface instead of using the management interface's IP address.
Tha dynamic interface is on the same subnet/vlan of the RADIUS server.
which is the best interface to use for RADIUS authentications?
And how can I decide which interface shuold be the IP radius-source interface for connecting with my radius servers?
If you have the Radius server on a subnet in which you have any interface on the wlc on, you will see the wlc using that interface ip address. The AAA client ip address you should use is the dynamic interface ip address. The only time you will see the wlc use its management interface is when your wired and wireless (dynamic interfaces) are on different subnets.