Abstract: A communication system includes: a plurality of active paths on which a plurality of signals set with priorities are transmitted by a plurality of time-division slots; a backup path shared by the plurality of active paths; and a controller configured to control, based on the priorities, allocation of any of the plurality of signals which are allocated to any of the plurality of time-division slots and transmitted on any of the plurality of active paths, to a plurality of time-division slots on the backup path.

Abstract: A packet transport network system includes a first node to transmit a control packet through a secondary port, when the first node does not periodically receive, through a primary port, a continuity check packet transmitted on the first MLSP set in the first direction; and a second node, when the second node receives the control packet through a secondary port, to relay or terminate packets on the first and second active MLSPs, to receive, through the primary port, the multicast packet transmitted on the second MLSP set in the second direction, and to bridge the received multicast packet to a recovery path set in an interested link, the second node periodically receiving, through a primary port, the continuity check packet transmitted on the second MLSP set in the second direction, wherein the first node receives, through the second port, the multicast packet bridged to the recovery path.

Abstract: A first route and a second route different from the first route are established between first and second nodes in a transmission system including a measuring unit and a computation unit. The measuring unit measures a first signal-transmission time indicating a time taken for a signal to be transmitted in a route starting from the first node and returning to the first node after passing through the first route, the second node, and the second route, and a second signal-transmission time indicating a time taken for a signal to be transmitted in a round-trip route of one of the first and second routes. The computation unit calculates, based on a measurement result of the measuring unit, a transmission time difference indicating a difference between transmission times of a signal transmitted through the first route and a signal transmitted through the second route in a transmission direction of the first signal.

Abstract: A ring network of a multicast label switch path scheme includes a transmitting node and receiving nodes connected to form a ring. A signal input to the transmitting node is branched to be transmitted in first and second different directions to first and second receiving nodes through first and second working paths, respectively, in the ring network. The first and second receiving nodes define terminal points of the first and second working paths, respectively, from the transmitting node. A first backup path is set from the first receiving node to the transmitting node, and a second backup path is set from the second receiving node to the transmitting node. The first backup path is in an opposite direction to the first working path and the second backup path is in an opposite direction to the second working path.

Abstract: A packet transport network system includes a first node to transmit a control packet through a secondary port, when the first node does not periodically receive, through a primary port, a continuity check packet transmitted on the first MLSP set in the first direction; and a second node, when the second node receives the control packet through a secondary port, to relay or terminate packets on the first and second active MLSPs, to receive, through the primary port, the multicast packet transmitted on the second MLSP set in the second direction, and to bridge the received multicast packet to a recovery path set in an interested link, the second node periodically receiving, through a primary port, the continuity check packet transmitted on the second MLSP set in the second direction, wherein the first node receives, through the second port, the multicast packet bridged to the recovery path.

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 communication network system includes a processor, and a plurality of node apparatuses using a protocol to establish paths therebetween, wherein the processor determines each of the node apparatuses to be a packet source or a packet destination, and operates to detect an occurrence of failure in two paths being established between the packet source and the packet destination in the communication network system, and wherein the processor transmits packet data including user data through one of the two paths, and when one of the node apparatuses detects an occurrence of a failure in one of the two paths, the processor changes the path to the other path.

Abstract: A ring network of a multicast label switch path scheme includes a transmitting node and receiving nodes connected to form a ring. A signal input to the transmitting node is branched to be transmitted in first and second different directions to first and second receiving nodes through first and second working paths, respectively, in the ring network. The first and second receiving nodes define terminal points of the first and second working paths, respectively, from the transmitting node. A first backup path is set from the first receiving node to the transmitting node, and a second backup path is set from the second receiving node to the transmitting node. The first backup path is in an opposite direction to the first working path and the second backup path is in an opposite direction to the second working path.

Abstract: An optical transmission apparatus connected to an optical ring network stores identification information of an optical transmission apparatus as a communication partner predetermined on a communication path. Each optical transmission apparatus includes self identification information in header information of an optical signal having a working wavelength used in normal operation, and transmits the optical signal to one of the two optical ring networks transferring optical signals in mutually opposite directions. The optical transmission apparatus determines whether the identification information included in the header information of the received optical signal having the working wavelength matches pre-stored identification information. The optical transmission apparatus thus detects a fault that occurs by the communication path.

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 path setting method for setting a backup path corresponding to a currently used path in a ring network using a label switching method includes setting an unused first label as a transmitting label of the backup path corresponding to the currently used path in a first direction; reporting the first label to a adjoining transmission device in the first direction; setting the first label as a receiving label of the backup path in the first direction; setting an unused second label as the transmitting label of the backup path in a second direction; reporting the second label to a adjoining transmission device in the second direction; and setting the second label as the receiving label of the backup path in the second direction, in which the backup path is set when the currently used path is set between two transmission devices.

Abstract: A relay device includes: a relay to relay a frame transmitted and received between transmission devices as a termination of a transferring path of a piece of data; an information generator to obtain a piece of path identification information for identifying the transferring path and a piece of device identification information for identifying the transmission device and generate a piece of control information based on the obtained piece of path identification information and the piece of device identification information; and an alarm signal transmitter to generate an alarm signal based on the control information generated by the information generator when an error occurs in the transferring path and transmit the generated alarm signal.

Abstract: A transmitter includes: a receiving unit to receive apparatus identification information that identifies transmitter and path identification information that identifies a data transfer path from another transmitter coupled to a local apparatus; a comparing unit to compare a value indicating an address assigned to the another transmitter to a value indicating an address assigned to the local apparatus; and a configuring unit to configure the local apparatus with apparatus identification information and path identification information determined by the local apparatus, or apparatus identification information and path identification information included in a frame received by the receiving unit, based on comparison results by the comparing unit.

Abstract: A communication network system includes a processor, and a plurality of node apparatuses using a protocol to establish paths therebetween, wherein the processor determines each of the node apparatuses to be a packet source or a packet destination, and operates to detect an occurrence of failure in two paths being established between the packet source and the packet destination in the communication network system, and wherein the processor transmits packet data including user data through one of the two paths, and when one of the node apparatuses detects an occurrence of a failure in one of the two paths, the processor changes the path to the other path.

Abstract: A system enabling inter-ring network connection when a plurality of ring networks are connected via a redundancy network, that is, a packet network system configured by a plurality of ring networks and redundancy networks linking the plurality of ring networks. This system virtually defines a plurality of virtual resilient packet ring networks among all of these packet networks and transfers packets on a designated virtual resilient packet ring network. Here, each virtual resilient packet ring network is identified by a virtual resilient packet ring network identifier allocated to each.

Abstract: An optical transmission apparatus connected to an optical ring network stores identification information of an optical transmission apparatus as a communication partner predetermined on a communication path. Each optical transmission apparatus includes self identification information in header information of an optical signal having a working wavelength used in normal operation, and transmits the optical signal to one of the two optical ring networks transferring optical signals in mutually opposite directions. The optical transmission apparatus determines whether the identification information included in the header information of the received optical signal having the working wavelength matches pre-stored identification information. The optical transmission apparatus thus detects a fault that occurs by the communication path.

Abstract: A system enabling inter-ring network connection when a plurality of ring networks are connected via a redundancy network, that is, a packet network system configured by a plurality of ring networks and redundancy networks linking the plurality of ring networks. This system virtually defines a plurality of virtual resilient packet ring networks among all of these packet networks and transfers packets on a designated virtual resilient packet ring network. Here, each virtual resilient packet ring network is identified by a virtual resilient packet ring network identifier allocated to each.

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: A path switching ring control apparatus is provided for use in a synchronous (SDH) network, and in particular for the purpose of repairing a fault which occurs in an asynchronous (PDH) subnetwork contained therein, this apparatus having a transmission alarm detection section which monitors the input PDH signal and generates a transmission alarm signal when a degradation of the quality thereof is detected, a path overhead generation section which generates the path overhead information of the transmission alarm signal from the transmission alarm detection section, and a path overhead insertion section which inserts the overhead information generated by the path overhead generation section into an SDH signal after the mapping thereof.