Abstract: A transmission device is connected to a layer 2 switch through a transmission path at one side, and to a relay transmission path at the other side. The transmission path includes a transmission path of a active system and a transmission path of a stand-by system. When failure occurs in the transmission path of the active system, the transmission device forcibly shuts down the transmission path of the active system upon detection of link down, to stop packet transmission, and causes the layer 2 switch to perform MAC address flush. The transmission device then switches the transmission path of the stand-by system to the active system, and transmits packets through the transmission path that has become the active system as a result of switching. The layer 2 switch performs MAC address learning to set a port, thereby maintaining communication even after occurrence of the failure.

Abstract: An ADM device which is capable of performing LCAS functions, configures a first communication network, and is connected to another ADM device which is connected to a second communication network, comprising an SDH interface for connecting to the other ADM device by SDH connection, an H4 byte monitoring means for monitoring the H4 byte of POH in the SDH interface, an LCAS control information acquisition means for acquiring LCAS control information from the H4 byte monitored by the H4 byte monitoring means, and an LCAS control information transmission means for transmitting LCAS control information acquired by the LCAS control information acquisition means to the other ADM devices, thereby providing an ADM device and signal transmission method which comprises a function for efficiently handling sharp variations in traffic, promotes work efficiency of transmission capacity increase/decrease speed within ADM systems, and actualizes the facilitation of management.

Abstract: In an L2 switch having a VLAN function for configuring a layer 2 network in a star topology, a mesh topology, a ring topology, or the like, a VLAN functional portion maps a frame to a predetermined VLAN, a frame classifying portion assigns to the frame a first tag indicating a priority, and a policing portion assigns to the frame a second tag indicating whether or not the frame can be discarded. Also, an OAM monitor inserts a monitoring frame to the VLAN.

Abstract: A transmission device is connected to a layer 2 switch through a transmission path at one side, and to a relay transmission path at the other side. The transmission path includes a transmission path of a active system and a transmission path of a stand-by system. When failure occurs in the transmission path of the active system, the transmission device forcibly shuts down the transmission path of the active system upon detection of link down, to stop packet transmission, and causes the layer 2 switch to perform MAC address flush. The transmission device then switches the transmission path of the stand-by system to the active system, and transmits packets through the transmission path that has become the active system as a result of switching. The layer 2 switch performs MAC address learning to set a port, thereby maintaining communication even after occurrence of the failure.

Abstract: An ADM device which is capable of performing LCAS functions, configures a first communication network, and is connected to another ADM device which is connected to a second communication network, comprising an SDH interface for connecting to the other ADM device by SDH connection, an H4 byte monitoring means for monitoring the H4 byte of POH in the SDH interface, an LCAS control information acquisition means for acquiring LCAS control information from the H4 byte monitored by the H4 byte monitoring means, and an LCAS control information transmission means for transmitting LCAS control information acquired by the LCAS control information acquisition means to the other ADM devices, thereby providing an ADM device and signal transmission method which comprises a function for efficiently handling sharp variations in traffic, promotes work efficiency of transmission capacity increase/decrease speed within ADM systems, and actualizes the facilitation of management.

Abstract: In an L2 switch having a VLAN function for configuring a layer 2 network in a star topology, a mesh topology, a ring topology, or the like, a VLAN functional portion maps a frame to a predetermined VLAN, a frame classifying portion assigns to the frame a first tag indicating a priority, and a policing portion assigns to the frame a second tag indicating whether or not the frame can be discarded. Also, an OAM monitor inserts a monitoring frame to the VLAN.