Abstract: In a data transmission method and apparatus which can perform a switchover of all of the main lines without requiring much construction cost, a transmission apparatus sets, upon frame transmission or reception, combinations of a plurality of main lines with virtual paths established so as to include at least a part of a bandwidth of the main lines in one or more protection lines as redundant configurations. Upon frame transmission, the apparatus copies frames received in the main lines, assigns identifiers of the redundant configurations to the copied frames, and transmits the copied frames to the virtual paths of the redundant configurations.

Abstract: The present invention provides a carrier network in which a spanning tree with no loops can be constructed even in a dual homing configuration, and a communication method for a control frame. By allocating an identical virtual network identifier to a plurality of user networks connected to the carrier network, a single virtual network is constituted. An ingress communication node connected to a first user network of the plurality of user networks attaches a tag including the virtual network identifier to a control frame transmitted from the first user network, and transmits the control frame attached with the tag to a transmission destination determined on the basis of the virtual network identifier.

Abstract: A resilient packet network (RPR) device is connected to one or more rings to constitute an RPR network. The RPR device has a storage unit in which a correspondence between RPR device addresses, each indicating an RPR device connected to the one or more rings, and user device addresses, each indicating a user device accommodated in the RPR device, is stored. When the RPR device receives data addressed to a predetermined user device from a user device accommodated in the RPR device itself, if an RPR device address of an RPR device accommodating the predetermined user device is registered in the storage unit, an RPR header, in which the RPR device address is set as a destination RPR device address, is added to the data. The data with the RPR header is transmitted to the RPR network.

Abstract: In a network providing a wide-area LAN service which allows communications to be performed between user networks (12, 13) via a carrier network (11), edge switches (14, 15) each comprise: a tentative learning registration means (16) which, when a packet whose source MAC address and receiving port are not yet learned is received from the carrier network, registers the source MAC address and the receiving port in a tentatively learned state; a learned state changing means (17) which changes the learned state of the destination MAC address of a packet received from an associated one of the user networks to a permanently learned state; and a permanent learning registration means which, when a packet whose destination MAC address is registered in a learned state is received from the carrier network, registers the source MAC address and receiving port of the packet received from the carrier network in a permanently learned state.

Abstract: In a data transmission method and apparatus which can perform a switchover of all of the main lines without requiring much construction cost, a transmission apparatus sets, upon frame transmission or reception, combinations of a plurality of main lines with virtual paths established so as to include at least a part of a bandwidth of the main lines in one or more protection lines as redundant configurations. Upon frame transmission, the apparatus copies frames received in the main lines, assigns identifiers of the redundant configurations to the copied frames, and transmits the copied frames to the virtual paths of the redundant configurations.

Abstract: A layer 2 switch includes a first control unit for, when receiving a frame broadcast-transferred in a layer 2 switch located on a transmission source terminal side, if a destination MAC address included in the frame has already been learned and a transmission source MAC address has not been learned, transmitting a virtual response frame supposing a response frame to be originally transmitted from a destination terminal, from a port that has received the frame, and a second control unit for discarding the virtual response frame received from a layer 2 switch located on the destination terminal side.

Abstract: A route bypassing a root node is constructed in a network in which a spanning tree is formed. A received frame is sent out on a designated port as well as on a root port by using a designated-port data send-out function, provided that a transmitting port for the received frame is learned on the root port. When a frame is received on a blocking port, a transmitting port for a frame whose destination matches the source address of the received frame is temporarily learned on the blocking port by using a blocking-port learning function, on the condition that the destination of the received frame is already learned on some other port. When a frame whose destination matches the temporarily learned address is received, the temporary learning is changed to normal learning by using a temporarily learned address-based data transfer function.

Abstract: In a network providing a wide-area LAN service which allows communications to be performed between user networks (12, 13) via a carrier network (11), edge switches (14, 15) each comprise: a tentative learning registration means (16) which, when a packet whose source MAC address and receiving port are not yet learned is received from the carrier network, registers the source MAC address and the receiving port in a tentatively learned state; a learned state changing means (17) which changes the learned state of the destination MAC address of a packet received from an associated one of the user networks to a permanently learned state; and a permanent learning registration means which, when a packet whose destination MAC address is registered in a learned state is received from the carrier network, registers the source MAC address and receiving port of the packet received from the carrier network in a permanently learned state.

Abstract: A resilient packet network (RPR) device is connected to one or more rings to constitute an RPR network. The RPR device has a storage unit in which a correspondence between RPR device addresses, each indicating an RPR device connected to the one or more rings, and user device addresses, each indicating a user device accommodated in the RPR device, is stored. When the RPR device receives data addressed to a predetermined user device from a user device accommodated in the RPR device itself, if an RPR device address of an RPR device accommodating the predetermined user device is registered in the storage unit, an RPR header, in which the RPR device address is set as a destination RPR device address, is added to the data. The data with the RPR header is transmitted to the RPR network.

Abstract: The present invention provides a carrier network in which a spanning tree with no loops can be constructed even in a dual homing configuration, and a communication method for a control frame. By allocating an identical virtual network identifier to a plurality of user networks connected to the carrier network, a single virtual network is constituted. An ingress communication node connected to a first user network of the plurality of user networks attaches a tag including the virtual network identifier to a control frame transmitted from the first user network, and transmits the control frame attached with the tag to a transmission destination determined on the basis of the virtual network identifier.

Abstract: A route bypassing a root node is constructed in a network in which a spanning tree is formed. A received frame is sent out on a designated port as well as on a root port by using a designated-port data send-out function, provided that a transmitting port for the received frame is learned on the root port. When a frame is received on a blocking port, a transmitting port for a frame whose destination matches the source address of the received frame is temporarily learned on the blocking port by using a blocking-port learning function, on the condition that the destination of the received frame is already learned on some other port. When a frame whose destination matches the temporarily learned address is received, the temporary learning is changed to normal learning by using a temporarily learned address-based data transfer function.