Bonding PPTP Client Tunnel , how ?

Dear all,

I am having difficulties on bonding two PPTP Client Tunnel. It seemed bonding didint recognize tunneling interface.
Need help.
Thanks b4.

bonding is only for Ethernet interfaces or Like-Ethernet (Wireless or EoIP)

so if the both ends use ROS, run EoIP over PPTP and then bond both of EoIP.