In a PPP gateway apparatus comprising a plurality of line interfaces each accommodating one of access lines for connecting to client terminals and core lines for connecting to layer 2 frame forwarding apparatuses, a frame forwarding control table, and a frame processor for controlling frame forwarding, the frame forwarding control table includes table entries each indicating the correspondence of a PPP session number to a client MAC address and frame definition information for the core line, and the frame processor operates, based on the frame forwarding control table, to forward a PPP frame received from one of access lines to one of core lines after converting it into a layer 2 Ethernet frame and to forward a frame received from one of the core lines and destined for a particular client MAC address to one of access lines after converting it into a PPP frame.