Abstract: A protection path providing method is used in a network that includes a shared section in which a first protection path corresponding to a first work path to transmit a first traffic and a second protection path corresponding to a second work path to transmit a second traffic are configured. The method includes: transmitting a message that includes information indicating a transmission rate of the first work path via a logical ring, the logical ring being formed using a route for which the first work path is configured and a route for which the first protection path is configured, when a failure is detected in the first work path; and controlling a switch circuit installed in a transmission device provided at an end of the shared section in accordance with the message in such a manner as to transmit the first traffic via the shared section.

Abstract: A connection node is included in a connecting part of a plurality of rings in a ring network. The connection node includes a failure detecting unit, an optical-signal processing unit, an ODU switch, and an optical-signal processing unit. The failure detecting unit detects failure in the connecting part. The optical-signal processing unit receives data transmitted from another node on a ring to which the connection node belongs. Upon detection of the failure, the ODU switch determines whether to pass the data or return the data in reverse direction from the connection node depending on a destination to transfer the received data, and sets a transmission path of the data based on a result of the determination. The optical-signal processing unit transfers the data in accordance with the set transmission path.

Abstract: An HO ODU signal input to an optical transmission apparatus is disassembled into LO ODUs. LO ODUs specified to form an aggregated ODU are disassembled not into individual LO ODUs but into a unit of an LO ODU group that forms an aggregated ODU. Clock extraction and an alarm process are performed not for the individual LO ODUs but for each aggregated ODU. This eliminates the need for a hardware configuration for performing the clock extraction and the alarm process in units of LO ODUs, leading to saving of hardware resources.

Abstract: A communication system includes a work path and a protection path that are set between a first transfer apparatus and a second transfer apparatus, one of the work path and the protection path being selected by the first transfer apparatus and the second transfer apparatus according to a control signal that includes first information indicating whether there is a failure in one of the work path and the protection path, and a third path that is activated when the first transfer apparatus or the second transfer apparatus receives a control signal in which the first information has been changed to second information indicating that a failure had occurred in both the work path and the protection path and is selected by the first transfer apparatus and the second transfer apparatus.

Abstract: A communication apparatus used as a first communication apparatus in a communication system having a ring network, the communication apparatus including: a storage unit configured to store information indicating a correspondence between a state of a path provided on the ring network, a state of a first link established between the first and third communication apparatuses, a state of a second link established between the second and third communication apparatuses, and a direction of forwarding the data; and a control unit configured to monitor links that are included in the ring network, and presence or absence of a failure occurring in each of the first and second links, and determine a direction of forwarding data to which path identification information corresponding to the third communication apparatus is added based on a result of the monitoring and the information stored in the storage unit.

Abstract: In a multi-ring communication network, first and second rings include first and second connection nodes, respectively, that are adjacently connected to each other. The first connection node receives, from adjacent nods, traffic information storing a pair of input and output node identifiers in association with each of storage areas included in a frame to be transmitted, where the input node identifier identifies an adjacent node from which data is inputted, and the output node identifier identifies an adjacent node to which the data is outputted. When the received traffic information includes the output node identifier identifying the second connection node, the first connection node sets a plurality of redundant path segments each including the second connection node, based on the received traffic information, where the plurality of redundant path segments includes a currently-used path segment.

Abstract: A data relay apparatus for data relay in a ring-type network for data including a path identifier which is transferred according to the path identifier, receives the data; stores the path identifier that is used to determine a data path in which the data is transferred in the ring-type communication network in association with a reception direction and a transmission direction of the data; compares the path identifier included in the received data and the path identifier stored by an information storing part to determine a path for receiving and transmitting the data and switches the transmission direction of the data based on a reception direction of a failure notification message notified when a communication failure occurs and whether a switching inhibition message transmitted concerning the communication failure is received; and transmits the data in the switched transmission direction.

Abstract: A connection node is included in a connecting part of a plurality of rings in a ring network. The connection node includes a failure detecting unit, an optical-signal processing unit, an ODU switch, and an optical-signal processing unit. The failure detecting unit detects failure in the connecting part. The optical-signal processing unit receives data transmitted from another node on a ring to which the connection node belongs. Upon detection of the failure, the ODU switch determines whether to pass the data or return the data in reverse direction from the connection node depending on a destination to transfer the received data, and sets a transmission path of the data based on a result of the determination. The optical-signal processing unit transfers the data in accordance with the set transmission path.

Abstract: A conventional edge device is constituted of a switching device and a transmission device. The switching device determines an ODU as an accommodation destination for an L2 packet from a client side device in accordance with an L2 ID, and outputs the L2 packet to an output port to which the ODU is associated. The transmission device receives an L2 packet through an input port corresponding to an output port of the switching device in a one-to-one manner, and performs transparent mapping on the corresponding ODU so as to output the signal by using an ODU connection.

Abstract: A method provides a communication path in a ring network having a plurality of communication nodes. The method includes: setting transfer information of data in each of the plurality of communication nodes by making the transfer information correspond to connection information for identifying a connection within the ring network to provide a first communication path; determining whether to update the transfer information in each of the communication nodes according to the position where the fault occurs; and updating the transfer information according to the position where the fault occurs in one or more of communication nodes to provide a second communication path. Each of the plurality of communication nodes transfers input data by using the first or second communication path according to transfer information corresponding to connection information attached to the input data.

Abstract: A node apparatus in a ring network in which a protection path is provided that cycles around the ring network and transports a signal in a direction opposite to a signal transporting direction of the working path and in the event of a failure of the working path, a node apparatus adjacent to the failure loops back the signal flowing on the working path onto the protection path, the node apparatus comprising: allowable bandwidth storing unit which stores a maximum total bandwidth value, which represents the largest value among per-link total values of bandwidths that a plurality of working paths use on respective links connecting between the node apparatuses, as an allowable bandwidth for a shared path; and bandwidth control unit which controls the bandwidth of traffic flowing on the protection path, in accordance with the allowable bandwidth.

Abstract: An optical transmission device in an optical transmission network including nodes, provided to one of the nodes, the optical transmission device including: a receiver to receive optical signals which have different wavelengths and are multiplexed, an optical detector to detect a strength of the optical signals, a switch to set switching control information including switching request information, each corresponding to one optical signal of the optical signals, and a transmitter to transmit the switching control information by an optical signal, wherein the switch sets, in information indicating a signal fail, the switching request information corresponding to the one optical signal in the switching control information based on the strength of one optical signal of the optical signals.

Abstract: An object is to simplify a process performed due to a failure recovery. To realize this object, the transmission apparatus includes a determining unit that determines, when a transmission apparatus receives a frame from each ring in a network including multiple rings in which a part of each ring is shared, whether failure information indicating that a failure has occurred in one of the rings is contained in one of the received frames. The transmission apparatus also includes a mapping unit that maps a frame that is determined by the determining unit to contain the failure information, onto a shared frame that is a frame used in a shared portion in the multiple rings. Accordingly, the process performed due to a failure recovery can be simplified.

Abstract: In a multi-ring communication network, first and second rings include first and second connection nodes, respectively, that are adjacently connected to each other. The first connection node receives, from adjacent nods, traffic information storing a pair of input and output node identifiers in association with each of storage areas included in a frame to be transmitted, where the input node identifier identifies an adjacent node from which data is inputted, and the output node identifier identifies an adjacent node to which the data is outputted. When the received traffic information includes the output node identifier identifying the second connection node, the first connection node sets a plurality of redundant path segments each including the second connection node, based on the received traffic information, where the plurality of redundant path segments includes a currently-used path segment.

Abstract: An HO ODU signal input to an optical transmission apparatus is disassembled into LO ODUs. LO ODUs specified to form an aggregated ODU are disassembled not into individual LO ODUs but into a unit of an LO ODU group that forms an aggregated ODU. Clock extraction and an alarm process are performed not for the individual LO ODUs but for each aggregated ODU. This eliminates the need for a hardware configuration for performing the clock extraction and the alarm process in units of LO ODUs, leading to saving of hardware resources.

Abstract: A system that allows information of MPLS layers to be reported to PW layers by providing a function having a correlation between MPLS layers and PW layers. A PE uses MPLS (Multi-Protocol Label Switching) tunneling and label technology to map a communication service to MPLS, thereby providing bidirectional services on an end-to-end basis. a communication system comprising the PE to perform label assignment control for bidirectional services, the PE to transmit, after completion of assignment control, a message in which the LDP message used in assignment control is a payload and a tunnel-directed label (L2) used by bidirectional services is a header and the PE to associate, on the basis of the received LDP message used in assignment control, a service-directed label (P1) included in the LDP message with the received tunnel-directed label (L2) in the part where the message is terminated.

Abstract: A data relay apparatus that recovers a failure in a network that shares a part of a plurality of rings and avoids occurrence of a loop path by providing a block in each of the rings includes a failure-notification-packet transmitting unit that transmits, when a failure is detected in a shared portion of a ring, a failure notification packet to a predetermined redundancy-providing ring; and a block setting unit that sets a block that blocks a main signal by passing through a control packet at a port where the failure is detected.

Abstract: A communication apparatus used as a first communication apparatus in a communication system having a ring network, the communication apparatus including: a storage unit configured to store information indicating a correspondence between a state of a path provided on the ring network, a state of a first link established between the first and third communication apparatuses, a state of a second link established between the second and third communication apparatuses, and a direction of forwarding the data; and a control unit configured to monitor links that are included in the ring network, and presence or absence of a failure occurring in each of the first and second links, and determine a direction of forwarding data to which path identification information corresponding to the third communication apparatus is added based on a result of the monitoring and the information stored in the storage unit.

Abstract: An extra traffic is transmitted in a redundant communication network using a backup path. A working communication path and the backup communication path connect two switching nodes. A switching control packet including information representing whether a first traffic passes through the working communication path is transmitted between the two switching nodes via the backup communication path. Under normal conditions, the first traffic passes the working communication path. A backup node that has received the second traffic from outside the backup communication path, determines whether the first traffic is passing through the working communication path based on information included in the switching control packet. If the first traffic is passing through the working communication path, the backup node transmits the second traffic to another backup node along the backup communication path.

Abstract: A switch that performs packet forwarding processing based on a label for a connection in which a communication path is specified by the label, includes a receiving unit that receives loopback information with a label of a first layer used for packet forwarding for a first connection, and a packet processing unit that transmits a first loopback packet having a packet including the loopback information, a label of the first layer, and a label of a second layer used for packet forwarding for a second connection layered on the label of the first layer, and also transmits a second loopback packet having the packet including the loopback information and the label of the second layer.