Patent ID: 8437349

Claim:
A network system that forms an L2VPN for relaying a MAC frame being forwarded among a plurality of points in a user network, comprising: a core switch that relays a MAC-in-MAC frame in which the MAC frame is encapsulated; and an edge switch that relays the MAC frame between the user network and the core switch with conversion between the MAC frame and the MAC-in-MAC frame, wherein the edge switch includes: a join message identification unit that identifies, from among MAC frames from the user network before encapsulating the MAC frame into the MAC-in-MAC frame, a join message being forwarded to a router from a host to join a multicast group; and a marking unit that marks a header of a MAC-in-MAC frame in which the identified join message is encapsulated, with mark information indicating the identified join message, wherein the core switch includes: a plurality of input/output ports that performs input and output of a layer 2 frame; a mark identification unit that identifies, from among MAC-in-MAC frames which are input through the plurality of input/output ports, a MAC-in-MAC frame in which a header is marked with the mark information; and a port setup unit that associates a multicast group of a join message which is encapsulated in the identified MAC-in-MAC frame, with an input/output port to which the identified MAC-in-MAC frame is input.