Hello, thanks for choosing Dell.   MXL-40G(conf)#ip radius source-interface ?fortyGigE               FortyGigabit Ethernet interfacegigabitethernet         Gigabit Ethernet interfaceloopback                Loopback interfacenull                    Null interfaceport-channel            Port Channel interfacetengigabitethernet      TenGigabit Ethernet interfacetunnel                  Tunnel interfacevlan                    Vlan interfaceMXL-Cristo(conf)#ip radius source-interface   We can assign as the source interface given above interfaces only on the MXL switches. We cannot assign to mgmt interface directly on MXL switch. Please create layer 3 vlan interface and associated any available port.
Our MXL 10/40 has management port configured with an IP address and management route. However there doesn't seem to be any way to use AAA servers if the management interface is used for management. The logical command would be "ip radius source-interface " but the management interface isn't one of the options for this command. When Radius servers are configured, the switch is unable to reach them.  However the switch is able to ping them with the command ping x.x.x.x source-interface management 0/0. Is it just not possible to use AAA server authentication in conjunction with the management interface?  
MXL Force10 Use Management Interface as Source Interface for Radius/Tacacs