Abstract: Provided is a method of controlling a network concentrator 100 which controls a link status between, of a plurality of ports 102, 104, 106, 108, at least one port 102, 104, 106 that belongs to a first group 10 and at least one port 108 that belongs to a second group 12 corresponding to the first group 10. The method comprises the steps of: detecting that each of the ports that respectively belong to the first group 10 and the second group 12 is link-up or link-down; and as a result of the detection step, if at least one port in one group of the first group 10 and the second group 12 is link-up and all the ports in the other group are link-down, setting the link-up port in the one group to disablement.

Abstract: A communication device capable of improving power saving is provided. A communication device (1) includes a communication port (10); communication monitoring sections (18, 22) for controlling information communication using the communication port, a status indicating section (12) having one or more status indicators, a status indicator driving section (20) for controlling a drive signal which detects a communication status from the communication monitoring sections and is supplied to the status indicating section on the basis of the communication status, and a lighting control section (24) for detecting the communication status from the communication monitoring sections and outputting a control signal to the status indicator driving section if the communication status changes from a first status to a second status. The status indicator driving section controls the drive signal so as to turn off the status indicators when the control signal is outputted from the lighting control section.

Abstract: Provided is a method of controlling a network concentrator 100 which controls a link status between, of a plurality of ports 102, 104, 106, 108, at least one port 102, 104, 106 that belongs to a first group 10 and at least one port 108 that belongs to a second group 12 corresponding to the first group 10. The method comprises the steps of: detecting that each of the ports that respectively belong to the first group 10 and the second group 12 is link-up or link-down; and as a result of the detection step, if at least one port in one group of the first group 10 and the second group 12 is link-up and all the ports in the other group are link-down, setting the link-up port in the one group to disablement.

Abstract: A communication device capable of improving power saving is provided. A communication device (1) includes a communication port (10); communication monitoring sections (18, 22) for controlling information communication using the communication port, a status indicating section (12) having one or more status indicators, a status indicator driving section (20) for controlling a drive signal which detects a communication status from the communication monitoring sections and is supplied to the status indicating section on the basis of the communication status, and a lighting control section (24) for detecting the communication status from the communication monitoring sections and outputting a control signal to the status indicator driving section if the communication status changes from a first status to a second status. The status indicator driving section controls the drive signal so as to turn off the status indicators when the control signal is outputted from the lighting control section.

Abstract: An optical communication device enabling confirmation of frames flowing through a communication line without affecting such line. The optical communication device includes a first conversion unit that converts a first optical signal transmitting a first frame group including a first maintenance frame into a first electrical signal; a frame duplication unit that receives the first electrical signal, generates a second electrical signal that transmits the first frame group, and outputs the first electrical signal; a second conversion unit that converts the first electrical signal output by the frame duplication unit into a second optical signal; and a third conversion unit that converts the second electrical signal generated by the frame duplication unit into a third optical signal.

Abstract: A method and apparatus capable of implementing user access control in a bus network at a low cost, and a bus network system in which low-cost security is implemented. A value of an FCS field in an Ethernet frame transmitted between a client U1 that is permitted to communicate with a server S among multiple clients U1 to U5 connected to a bus network and the server S is reversibly converted so that the Ethernet frame is converted into an FCS error frame. The value of the FCS field in the Ethernet frame converted into the FCS error frame and transmitted is restored to the original FCS value.

Abstract: An optical communication device enabling confirmation of frames flowing through a communication line without affecting such line. The optical communication device includes a first conversion unit that converts a first optical signal transmitting a first frame group including a first maintenance frame into a first electrical signal; a frame duplication unit that receives the first electrical signal, generates a second electrical signal that transmits the first frame group, and outputs the first electrical signal; a second conversion unit that converts the first electrical signal output by the frame duplication unit into a second optical signal; and a third conversion unit that converts the second electrical signal generated by the frame duplication unit into a third optical signal.

Abstract: A data conversion technique allows efficient processing of fixed-length data even when a remainder is produced by dividing the variable-length by a predetermined fixed length. A remainder data length is produced by dividing variable-length data in units of a predetermined fixed length and an added data length is determined by subtracting the remainder data length from the predetermined fixed length. By adding addition data including the remainder data length to the variable-length data, data allowing fixed-length processing is obtained.