Patent ID: 7701939

Claim:
An OLT (Optical Line Terminal) provided as a center side network element in an optical access network system which connects a plurality of subscriber terminals to a network, comprising: a multicast control unit, which is provided with a multicast communication dedicated port for multicast communication services connected to the network; and a plurality of packet data transmission and reception control units for accommodating the plurality of subscriber terminals, each provided with a unicast communication dedicated port for unicast communication services connected to the network; wherein the multicast control unit comprises: a first filter information table for specifying one or more of the plurality of packet data transmission and reception control units as distribution destinations of the received multicast data packets, wherein the first filter information table contains, for the specified packet data transmission and reception control units, a multicast group identifier corresponding to each of the subscriber terminals accommodated by each of the plurality of packet data transmission and reception control units; and a first distribution control section, which identifies each of the packet data transmission and reception control units necessary for distributing the multicast data packets received from the network and distributes the multicast data packets to the respective identified packet data transmission and reception control units; and wherein the packet data transmission and reception control unit comprises: a second filter information table for specifying one or more of the plurality of subscriber terminals as distribution destinations of the multicast data packets distributed from the multicast control unit, wherein the second filter information table contains the multicast group identifier and the logical link identifier associated with the specified subscriber terminals accommodated by the packet data transmission and reception control unit; and a second distribution control section, which identifies each of the subscriber terminals necessary for transmitting the multicast data packets distributed from the multicast control unit, multiplexes the multicast data packets with unicast data packets received via the unicast communication dedicated port, and transmits the multiplexed data packets to the subscriber terminals.