Abstract: An apparatus can relieve Ethernet signal failure at connections of Ethernet with SDH/SONET network. In the apparatus, each of current and spare system paths including alarm detecting unit that receives Ethernet signal through a router to detect failure of Ethernet signal; a converting unit that converts Ethernet signal to an SDH/SONET signal, the converting unit converting the SDH/SONET signal to the Ethernet signal; a path switch controlling unit that outputs an insert instruction of an alarm signal for the SDH signal converted by the converting unit when the alarm detecting unit detects failure; an alarm inserting unit that inserts the alarm signal into the SDH/SONET signal based on the insert instruction of the alarm signal from the path switch controlling unit; and a path switch unit that detects the alarm signal inserted into the SDH signal from the alarm inserting unit to switch the path to the spare system.

Abstract: In a state where although the setting of a line between a transmitting station and a receiving station is completed, no signal is transmitted, a test signal in a prescribed format is transmitted from the transmitting station. By transmitting the test signal, no signal disconnection is detected by each alarm detection point, and no alarm occurs. When a regular signal is transmitted from the transmitting station to the receiving station, the test signal is automatically switched to a regular signal on the transmitting station side.

Abstract: Proposed is an optical clock distribution system in the WDM network, which particularly relates to a system to control clock synchronization between optical transmission devices constituting an optical communication network. The optical clock distribution system includes an optical clock generator converting a clock signal of PRC (Primary Reference Clock) level into an optical clock signal having a wavelength ?0; a wavelength multiplexer wavelength-multiplexing the optical clock signal having wavelength ?0 together with other optical wavelength data; and a wavelength-demultiplexer provided in a unit of the network, wavelength-demultiplexing the optical clock signal having wavelength ?0, wherein the other optical wavelength data are processed in the unit of the network using the wavelength-demultiplexed optical clock signal having wavelength ?0 as a reference clock.

Abstract: Communication nodes respectively comprise a function for transmitting/receiving a digital wrapper frame. SDH devices transmitting/receiving an SDH frame are connected to some of the communication nodes, and Ethernet devices transmitting/receiving an Ethernet packet are connected to some others of the communication nodes. An SDH frame and an Ethernet packet are stored in a payload of a digital wrapper frame, and transmitted between communication nodes. A network management device manages a connection relationship among the communication nodes, and paths set up on a digital wrapper network. The communication nodes respectively transfer a digital wrapper frame in accordance with an instruction from the network management device.

Abstract: A network synchronization controller and method for effectively preventing a timing loop from happening in a synchronous network. A clock status message controller, disposed in each network element on the network, produces and sends clock status messages which are each composed of clock quality data and synchronization control data. The clock quality data indicates the quality level of a clock signal that each network element supplies to its neighboring network elements. The synchronization control data contains information to be used to make the network synchronized with a single reference timing source. A clock selector chooses one of the clock signals received from other network elements, based on the clock status messages received along with the clock signals.

Abstract: Proposed is an optical clock distribution system in the WDM network, which particularly relates to a system to control clock synchronization between optical transmission devices constituting an optical communication network. The optical clock distribution system includes an optical clock generator converting a clock signal of PRC (Primary Reference Clock) level into an optical clock signal having a wavelength &lgr;0; a wavelength multiplexer wavelength-multiplexing the optical clock signal having wavelength &lgr;0 together with other optical wavelength data; and a wavelength-demultiplexer provided in a unit of the network, wavelength-demultiplexing the optical clock signal having wavelength &lgr;0, wherein the other optical wavelength data are processed in the unit of the network using the wavelength-demultiplexed optical clock signal having wavelength &lgr;0 as a reference clock.

Abstract: In order to increase the efficiency of large-capacity transmission, the continuity of divided signals generated by dividing a multiplexed signal is maintained and the original large-capacity multiplexed signal is restored. A signal dividing section divides a multiplexed signal to generate a plurality of divided signals in the STS or STM transmission interface format. A guarantee information adding section adds guarantee information for guaranteeing the continuity of the divided signals to each of the divided signals to generate transmission signals. A signal sending section sends the transmission signals via a transmission line in the transmission interface format. A signal receiving section receives the transmission signals. A signal restoring section restores the multiplexed signal by constructing the divided signals on the basis of the guarantee information.

Abstract: In a mesh-type network, a managing section manages QoS (Quality of Service) information, which is accumulated QoS information (inter-neighboring-node QoS information q) between neighboring node apparatuses, about QoS for candidate signal transmission routes in the network at the individual node apparatuses. And a control section controls a signal transmission route selection operation at the self node apparatus based on the network QoS information Q being managed by the managing section. With this construction, it is possible to set/manage a line route satisfying a desired QoS independently at the individual node apparatuses with maximum ease and flexibleness.