Patent ID: 7912071

Claim:
An optical line terminal (OLT), connected to a core network and a plurality of optical network units (ONUs), for supporting virtual LAN (VLAN) services, said OLT comprising: a VLAN translation control unit that creates a VLAN translation table indicating information on VLAN identifier (VID) translation relations among VIDs to show a correspondence relation between a source VID and a destination VID, which are waiting for translation, based on the VID translation relations, said information on VID translation relations among VIDS being sent from an OLT management server on the core network; a storage unit in which the VLAN translation table is saved; and a VLAN processing unit that checks if a VID included in a received frame must be translated based on the VLAN translation table and, if the VID must be translated, references the VLAN translation table to translate the VID included in the received frame to a corresponding destination VID, wherein said VLAN processing unit searches the VLAN translation table for the VID of the received frame and, if the VID of the received frame is the same as a source VID in the VLAN translation table, determines that the VID of the received frame must be translated, wherein the VID translation relations include a VLAN communication relation that indicates a correspondence relation between the VIDs of VLANs wishing to communicate with each other, wherein said VLAN translation control unit sets, based on the VLAN communication relation, the VID of the VLAN belonging to the OLT included in the VLAN communication relation to the destination VID in the VLAN translation table, and another VID corresponding to the destination VID described in the VLAN communication relation to the source VID, whereby VID translation is performed only for a received downstream frame if necessary, wherein said VLAN translation control unit is also used to create a logic link table (LLM) that includes an optical logic link identifier (OLID) identifying an ONU or an ONU port connected to the OLT, a VID of a VLAN belonging to the OLID, and an MAC address of a user of the OLT, said LLM table indicating a mapping relation among the OLID, the VID, and the user MAC address, and wherein said VLAN processing unit searches the LLM table for a an item including the same destination MAC address included in the received frame and, if the VID of the detected item is not the same as the VID included in the received frame, determines that the VID of the received frame must be translated.