Patent ID: 7636360
Filing Date: 2009-12-22
Classification: H04L

Abstract:
1. A virtual local area network (VLAN) system comprising: a plurality of layer 2 switches (L2SWs) serving a plurality of user terminals; a plurality of layer 2 gateways (L2GWs) serving the L2SWs; and a host network to which the L2GWs are connected, wherein a user terminal of the plurality of user terminals broadcasts a connection request by a tagged VLAN frame in which a common VLAN ID on the system is specified and a first packet is encapsulated, in accordance with a session establishment phase of a Point-to-Point Protocol over Ethernet (PPPoE) protocol, and waits for a second packet. wherein an L2SW of the plurality of L2SWs receives a frame from the user terminal, and if the frame is a tagged VLAN frame in which the common VLAN ID is specified and the first packet is encapsulated, the L2SW registers the user terminal address, waits for a second packet from an L2GW of the plurality of L2GWs, and transfers the received tagged VLAN frame to the L2GW to which transmission is allowed, wherein the L2GW receives the tagged VLAN frame from the L2SW, and if the frame is a tagged VLAN frame in which the common VLAN ID is specified and the first packet is encapsulated, and if it is determined that a service name requested by the user terminal can be connected, the L2GW registers a transmission source user terminal address, waits for a third packet from the user terminal, and sends a tagged VLAN frame containing the second packet to the user terminal, wherein the L2SW receives a frame from the L2GW, and if the frame is a tagged VLAN frame in which the common VLAN ID is specified, a second packet is encapsulated, and a transmission destination address is the user terminal address and if a second packet has been waited for, the L2SW registers the transmission source L2GW address in association with the user terminal address, waits for a third packet, and transfers the received tagged VLAN frame to the user terminal, wherein the user terminal receives a frame from the L2SW and if the frame is a tagged VLAN frame in which the common VLAN ID is specified and a second packet is encapsulated, if the second packet has been waited for, and if the service name extracted from the second packet has been registered, the user terminal registers the transmission source L2GW address, waits for a fourth packet, sends the tagged VLAN frame containing the third packet to the L2GW, and discards a frame from another L2GW, wherein the L2SW receives a frame from the user terminal, and if the frame is a tagged VLAN frame in which the common VLAN ID is specified and a third packet is encapsulated and if the transmission source address and the transmission destination address extracted from the third packet match the registered user terminal address and L2GW address, the L2SW waits for a fourth packet and transfers the received tagged VLAN frame to the L2GW, wherein the L2GW receives a frame from the L2SW, and if the frame is a tagged VLAN frame in which the common VLAN ID is specified and a third packet is encapsulated and if the transmission source address extracted from the third packet matches the address of the user terminal waiting for a third packet, the L2GW obtains and registers the VLAN ID to be assigned to the user terminal and reports the assigned VLAN ID by encapsulating a fourth packet having the assigned VLAN ID as a session ID in the tagged VLAN frame having the common VLAN ID, wherein the L2SW receives a frame from the L2GW, and if the frame is a tagged VLAN frame in which the common VLAN ID is specified and a fourth packet is encapsulated and if the transmission source address and the transmission destination address extracted from the second packet match the L2GW address and the user terminal address, the L2SW extracts the assigned VLAN ID from the fourth packet, enables transmission and reception of the tagged VLAN frame having the assigned VLAN ID with respect to the user terminal and the L2GW, and transfers the received tagged VLAN frame to the user terminal, and wherein the user terminal receives a frame from the L2SW, and if the frame is a tagged VLAN frame in which the common VLAN ID is specified and a fourth packet is encapsulated and if the transmission source L2GW address is registered, the user terminal enables transmission and reception of the tagged VLAN frame having the assigned VLAN ID with respect to the L2GW, and performs communication by using the assigned VLAN ID.