PPPoE server with BGP configured

Hi,

I’m running PPPoE server on the Mikrotik router, which is using BGP+OSPF routing stack.
So the router connected to other 2 routers using the routing stack and 2 different interfaces. There fore in my radius server I see connections coming from different sources (those are the interfaces, where OSPF is configured), so I had to setup both these IP-s in my clients.conf (freeradius).

What I would like to do is to make PPPoE server using looback IP address to connect to Freeradius server instead of randomly picking up an address from 2 WAN interfaces.

How could I solve it?

Actually solved.
Found the Source Address option for PPPoE server.