Abstract: A processor activates a first monitoring process for initializing a timer and a second monitoring process with higher priority than the first monitoring process. The processor executes the second monitoring process to monitor whether the first monitoring process has been executed. When determining that the first monitoring process has not been executed, the processor executing the second monitoring process determines whether the load state of the processor satisfies prescribed conditions. If the load state satisfies the prescribed conditions, the processor executing the second monitoring process initializes the timer.

Abstract: A method for packet forwarding, including receiving packets; extracting a test packet containing information indicating a path to be verified from the received packets; and forwarding the test packet to the path to be verified, rather than to a first path to which the received packets are forwarded, based on the information indicating the path to be verified contained in the test packet.

Abstract: A method for packet forwarding, including receiving packets; extracting a test packet containing information indicating a path to be verified from the received packets; and forwarding the test packet to the path to be verified, rather than to a first path to which the received packets are forwarded, based on the information indicating the path to be verified contained in the test packet.

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: 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: A transmission apparatus used for forming a network that supports a bidirectional ring switching capability is provided, in which the transmission apparatus includes: a detecting part for detecting a ring switching request from a received signal; an obtaining part for obtaining an identifier of a transmission apparatus included in the ring switching request, and obtaining concatenation setting information corresponding to the identifier; and a setting part for making concatenation setting for a protection line according to the concatenation setting information.

Abstract: An SDH ring network is disclosed, which comprises a transmission & reception node; and a PCA insertion & reception node, which are interconnected in a ring form. The transmission & reception node includes a first function portion for setting a working path and a protection path in advance, a second function portion for setting a transmission value into the K3 or K4 byte in the overhead part of an SDH signal independently on the working path and the protection path, and a path switch for selecting either the working path or the protection path depending on the state of the received K3 or K4 byte, and the PCA insertion & reception node includes an insertion switch for selecting either a received signal is to be passed through or a PCA (Protection Channel Access) signal is to be inserted thereto, and a bridge for dropping a received signal and at the same time passing through the received signal.

Abstract: There is provided a cross-connecting system capable of automatically detecting a connection error and a position where the connection error has occurred. The cross-connecting system has a cross-connecting apparatus which makes connection between a high-speed line and a low-speed line or between two high-speed lines so as to transfer a main signal therethrough. A line-connection information adding unit is provided for adding line-connection information to an overhead of the main signal. A line-connection information detecting unit is provided for detecting the line-connection information. A determining unit provides the line-connection information to the line-connection information adding unit, and determines a presence of a connection error along a line through which the main signal is transferred in accordance with the line-connection information received from a remote cross-connecting system.

Abstract: An optical transmission system includes a plurality of nodes connected via optical transmission lines in a ring form. When an optical transmission line is disconnected or a fault is found on the optical transmission device of a node, a transmission line is switched over to another transmission line by a line switching system which includes optical transmission lines of a working line for transmitting optical data signals and a protection line for transmitting APS (Automatic Protection Switch) bytes. Each of the nodes has a comparing and detecting unit for receiving the APS bytes sent from an adjacent node and comparing a fault pattern indicated by the APS bytes with a fault pattern stored in advance, and a processing unit which determines a line switching route, based on the result of comparison in the comparing and detecting unit.