Abstract: An optical pickup which has a failure prediction apparatus for predicting a failure of a laser diode has an input inputting a value of a current that flows through the laser diode and is measured at predetermined time intervals, a storage storing the current values inputted by said input, a detector detecting a current value that is a current value at any one of the measurement times of day stored in said storage and that has a change greater than or equal to a predetermined value relative to the current value at the preceding measurement time of day, and a generator generating a prediction curve that indicates a relationship between said elapsed time and the current value applicable at and after the measurement time of day of the current value detected by said detector.

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: An optical pickup which has a failure prediction apparatus for predicting a failure of a laser diode has an input inputting a value of a current that flows through the laser diode and is measured at predetermined time intervals, a storage storing the current values inputted by said input, a detector detecting a current value that is a current value at any one of the measurement times of day stored in said storage and that has a change greater than or equal to a predetermined value relative to the current value at the preceding measurement time of day, and a generator generating a prediction curve that indicates a relationship between said elapsed time and the current value applicable at and after the measurement time of day of the current value detected by said detector.

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: When setting up a working path, a protection path is automatically set up by taking each node on the working path as a start point. A working path setup request message carrying “protection needed/not-needed” information is transmitted from an ingress node toward an egress node along the route of the working path. When transferring a path setup response message as a response to it, each node autonomously determines the route of the protection path and sends out a protection path setup request message along the route of the protection path.

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: 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: When setting up a working path, a protection path is automatically set up by taking each node on the working path as a start point. A working path setup request message carrying “protection needed/not-needed” information is transmitted from an ingress node toward an egress node along the route of the working path. When transferring a path setup response message as a response to it, each node autonomously determines the route of the protection path and sends out a protection path setup request message along the route of the protection path.