is it possible to bridge only pppoe frames/packets between LAN & WAN.
i have pppoe server at wan side, & i dont want to mix all traffic.
how can I forward the PPPoE ethernet packets between the two networks wihtout introducing lots of unnecessary broadcast traffic?
relay pppoe server or something like that???

thnx

Without going into too many specifics the simplest in your case could be to use the bridge filters available on Mikrotik.

Add the appropriate ports to a bridge; then review the bridge filters and only allow the specified frame types.