vlan assign - 3com guest vlan

I would like to dynamic assign vlan to switch 3com , and i would like to mac based authentication. In 3com terminology it is called RADA. Every works fine, freeradius dynamically assign vlan for mac adresses includes in users.conf, But how to configure freeradius to work in this scenario: - freeradius check if it has proper mac addres in its users.conf, if it has it assign the proper vlan (it works !) - if it doesnt find a mac in a file it assign vlan for examle 15 (I dont know how to configure that in freeradius) in users.conf I have something: 00-0d-61-1b-6f-15 User-Password == "00-0d-61-1b-6f-15" Tunnel-Medium-Type = 6, Tunnel-Private-Group-Id := 101, Tunnel-Type = VLAN Please help Thanks in advance