Abstract: A frame transmission system includes a frame transmitter and a frame receiver. The frame transmitter includes a frame fragmentation unit and a reproduction header appending unit. The frame fragmentation unit fragments an input frame and outputs transfer frames when the length of the input frame exceeds a predetermined fragmentation reference frame length, and does not fragment the input frame and outputs the input frame as a transfer frame when the length of the input frame is less than or equal to the fragmentation reference frame length. The reproduction header appending unit appends a reproduction header to the transfer frames outputted from the frame fragmentation unit. Here, the reproduction header being required when the transfer frames are reproduced at a receiving side. The reproduction header appending unit varies the header length of the reproduction header to be appended to the transfer frame, according to the length of the input frame.

Abstract: A frame transmission system includes a frame transmitter and a frame receiver. The frame transmitter includes a frame fragmentation unit and a reproduction header appending unit. The frame fragmentation unit fragments an input frame and outputs transfer frames when the length of the input frame exceeds a predetermined fragmentation reference frame length, and does not fragment the input frame and outputs the input frame as a transfer frame when the length of the input frame is less than or equal to the fragmentation reference frame length. The reproduction header appending unit appends a reproduction header to the transfer frames outputted from the frame fragmentation unit. Here, the reproduction header being required when the transfer frames are reproduced at a receiving side. The reproduction header appending unit varies the header length of the reproduction header to be appended to the transfer frame, according to the length of the input frame.

Abstract: A first communication apparatus receives, from a second communication apparatus, information indicating the number of relays from a first supplying apparatus to the second communication apparatus. The first communication apparatus receives, from a third communication apparatus, information indicating the number of relays from a second supplying apparatus to the third communication apparatus. The first communication apparatus transmits, to the third communication apparatus, information indicating the number of relays from the first supplying apparatus to the first communication apparatus. The first communication apparatus transmits, to the second communication apparatus, information indicating the number of relays from the second supplying apparatus to the first communication apparatus. The first communication apparatus selects the second communication apparatus, which has a smaller number of relays among the second and the third communication apparatuses.

Abstract: According to an aspect of an embodiment, a node apparatus used in at least part of nodes in a network formed by a plurality of nodes coupled in the shape of a ring, comprising: a working node function performing unit for performing functions as a working apparatus that selectively drops a frame destined for a terminal hosted by the node itself among frames transmitted on the ring and adds a frame from the terminal hosted by the node itself to frames transmitted on the ring; a back-up function performing unit for performing functions as a back-up apparatus that lets a frame destined for a terminal hosted by the node itself pass through to an adjacent node and discards a frame from the terminal hosted by the node itself; and a function selection unit for selectively enabling one of the working node function performing unit and the back-up function performing unit.

Abstract: A first communication apparatus receives, from a second communication apparatus, information indicating the number of relays from a first supplying apparatus to the second communication apparatus. The first communication apparatus receives, from a third communication apparatus, information indicating the number of relays from a second supplying apparatus to the third communication apparatus. The first communication apparatus transmits, to the third communication apparatus, information indicating the number of relays from the first supplying apparatus to the first communication apparatus. The first communication apparatus transmits, to the second communication apparatus, information indicating the number of relays from the second supplying apparatus to the first communication apparatus. The first communication apparatus selects the second communication apparatus, which has a smaller number of relays among the second and the third communication apparatuses.

Abstract: According to an aspect of an embodiment, a node apparatus used in at least part of nodes in a network formed by a plurality of nodes coupled in the shape of a ring, comprising: a working node function performing unit for performing functions as a working apparatus that selectively drops a frame destined for a terminal hosted by the node itself among frames transmitted on the ring and adds a frame from the terminal hosted by the node itself to frames transmitted on the ring; a back-up function performing unit for performing functions as a back-up apparatus that lets a frame destined for a terminal hosted by the node itself pass through to an adjacent node and discards a frame from the terminal hosted by the node itself; and a function selection unit for selectively enabling one of the working node function performing unit and the back-up function performing unit.

Abstract: In a node device switching over a working system to a protection system at the time of a fault occurrence, a relative phase difference detector detects a relative phase difference of transmission delays of a working transmission line and a protection transmission line, a path error detector detects path errors on the transmission lines, and a main signal error calculator calculates errors of the main signals from the transmission lines, thereby specifying a position on which the fault has occurred based on the path errors and main signal error calculation results which are made in phase based on the relative phase difference.