MTR PPPoE with ISA-PROXY

Hiu,

USERS ====> eth0 MT PPPoE eth1 ====> ISA SERVER (10.0.0.1)

I want to authenticate all users with my MT PPPoE Server. then all request from pppoe client should be forwarded to ISA SERVER.

Do I have to setup BRIDGE (br0) & create pppoe on br0 ? & setup a forward rule to allow only pppoe clients to access ISASERVER ?