Method for supporting multicast service in ethernet passive optical network system

A multicast service supporting method, which is performed by an optical line terminal connected to a plurality of optical network unit systems in an Ethernet passive optical network, the method comprising:

• (a) determining whether or not a packet received to the optical line terminal system is a multicast packet;
• (b) if the packet is not the multicast packet, processing the packet using a unicast method or a broadcast method;
• (c) if the packet is the multicast packet, finding a port to be forwarded in a Layer 3 (L3) multicast forwarding table using a multicast IP address of the packet, the L3 multicast forwarding table including multicast IP address information and interface port information;
• (d) if the port is not a PON port, transmitting the multicast packet to the plurality of optical network unit systems;
• (e) if the port is a PON port, searching for a MLLID (Multicast Logical Link ID) value in a Layer 2 (L2) multicast forwarding table including multicast MAC addresses and identifier numbers of the plurality of optical network unit systems;
• and
• (f) if a multicast MAC address of the packet exists in the L2 multicast forwarding table, setting the MLLID value in a preamble of the packet and transmitting the packet to the plurality of optical network unit systems.

A multicast service supporting method, which is performed by each of a plurality of optical network unit systems connected to an optical line terminal system in an Ethernet passive optical network, the method Comprising:

• (a) determining whether or not a packet received to an optical network unit system is a multicast packet;
• (b) if the packet is not the multicast packet, processing the packet using a unicast method or a broadcast method;
• (c) if the packet is the multicast packet, determining whether or not a MLLID value included in a preamble of the packet is identical with a Multicast Logical Link ID (MLLID) value of the optical network unit;
• (d) if both the MLLID values are not the same, discarding the multicast packet;
• (e) if both the MLLID values are the same, finding a corresponding multicast MAC address from a Layer 2 (L2) multicast forwarding table including multicast MAC addresses and a corresponding port number of the optical network unit system and obtaining a list of subscriber ports to be forwarded;
• and (f) transmitting the multicast packet to a corresponding subscriber port included in the list of subscriber ports obtained in step (e).