Multicast snooping on layer 2 virtual private network

A core switch that relays a MAC-in-MAC frame in which a MAC frame is encapsulated, comprising:

• 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 to whose a header a mark information is marked, wherein the mark information indicates a join message being forwarded to a router from a host to be joining a multicast group;
• 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.

A method for relaying a MAC frame being forwarded among a plurality of points in a user network, comprising:

• relaying, by a core switch, a MAC-in-MAC frame in which the MAC frame is encapsulated, wherein the core switch includes a plurality of input/output ports that performs input and output of a layer 2 frame;
• and
• relaying, by a edge switch, 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 relaying by the edge switch includes:
• identifying, from among MAC frames from the user network, a join message being forwarded to a router from a host to be joining a multicast group;
• and
• marking 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 relaying by the core switch includes:
• identifying, from among MAC-in-MAC frames which are input through the plurality of input/output ports, a MAC-in-MAC frame to whose a header the mark information is marked;
• and
• associating 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.