Abstract: A transmission source node transmits diagnostic frames where a TTL value is set to the number of hops that is counted until an intermediate node. A relay node decrements the TTL value of the received diagnostic frames, counts the number of diagnostic frames where the decremented TTL value is 0, and recognizes continuity between the transmission source node and the relay node based on the number of transmitted diagnostic frames transmitted from the transmission source node and the number of diagnostic frames where the decremented TTL value is 0.

Abstract: The present invention measures 1-way delay without equipping all nodes with special functionality in a situation in which time has not been synchronized. The delay measurement system of the present invention has a transmission origin node and a transmission destination node which is connected to the transmission origin node through a network including relay nodes, and measures the delay time from the transmission origin node to the transmission destination node direction, wherein the transmission origin node generates a clock. On the basis of the generated clock, delay measurement packets are generated at regular periods. The generated delay measurement packets are transmitted to the transmission destination node. The transmission destination node selects the delay measurement packets from among the received frames. The delay received by the delay measurement packets in the network between the transmission origin node to the node itself is measured.

Abstract: In a transmission system capable of measuring packet loss ratio between arbitrary devices upon a transmission path without increasing bandwidth of an OAM frame band, a plurality of transmission devices which have been disposed upon a transmission path are provided with a frame analysis unit which receives data frames so as to analyze the type of the data frames, a count processing unit which stores the number of received frames included in the data frames into storage module provided beforehand, an output line end portion which outputs the data frames, and an OAM processing unit which calculates the packet loss ratio in the transmission path using the number of received frames. The frame analysis unit has a function which, if the data frames are OAM frames, copies the data frames and the OAM processing unit has a function which calculates the packet loss ratio using the copied OAM frames.

Abstract: An AIS management table 14 is storing entries having, as fields, an input port connected to a section, a section endpoint serving as an input destination, a path over which an AIS frame is to be output, and an output port connected to a section. When a failure is detected in a section, an AIS processing unit 19 searches an AIS management table 14 using, as a key, an input port or section endpoint involved in the location of the failure, inserts retrieved path information into an AIS frame for failure detection, and determines that a retrieved output port is the output destination of the AIS frame. A frame transfer unit 12 receives the AIS frame and information about the output port from the AIS processing unit 19 and transmits the AIS frame from the output port to an adjacent section.

Abstract: A node according to the present invention is used in an MPLS (Multi Protocol Label Switching) network, and the node includes an input unit which receives an OAM (Operation Administration and Maintenance) frame including TTL (Time To Live) from outside of the node and an output unit which transmits an OAM frame to outside of the node, wherein the input unit sets the TTL to a specific value and transmits the received OAM frame to the output unit in case a termination destination which an OAM frame received from outside indicates is the node and the received OAM frame is to be transmitted to the output unit and the output unit terminates an OAM frame transmitted from the input unit.

Abstract: A transmission source node transmits diagnostic frames where a TTL value is set to the number of hops that is counted until an intermediate node. A relay node decrements the TTL value of the received diagnostic frames, counts the number of diagnostic frames where the decremented TTL value is 0, and recognizes continuity between the transmission source node and the relay node based on the number of transmitted diagnostic frames transmitted from the transmission source node and the number of diagnostic frames where the decremented TTL value is 0.

Abstract: In a transmission system capable of measuring packet loss ratio between arbitrary devices upon a transmission path without increasing bandwidth of an OAM frame band, a plurality of transmission devices which have been disposed upon a transmission path are provided with a frame analysis unit which receives data frames so as to analyze the type of the data frames, a count processing unit which stores the number of received frames included in the data frames into storage module provided beforehand, an output line end portion which outputs the data frames, and an OAM processing unit which calculates the packet loss ratio in the transmission path using the number of received frames. The frame analysis unit has a function which, if the data frames are OAM frames, copies the data frames and the OAM processing unit has a function which calculates the packet loss ratio using the copied OAM frames.

Abstract: An inspection signal to inspect forward-path or return-path communication, is transmitted from a reference node of a network. A response signal is transmitted in a priority class from a node of a forward path to the reference node. In the case of inspection of return-path communication, a replica of the response signal is transmitted in a non-priority class from the node of the forward path to the return path, and the node that receives the replica of the response signal transfers the replica in a priority class to the reference node. In the case of inspection of forward-path communication, a replica of the inspection signal is transmitted in a non-priority class from the node of the forward path to the forward path, and a replica of the response signal is transmitted in a priority class from the node that receives a replica of the inspection signal to the reference node.

Abstract: A clock synchronization system synchronizes a clock of a slave node with a clock of a master node. The master node includes a packet transmitting unit that transmits a packet including a time stamp (TS) to the slave node. The slave node includes: a packet receiving unit that receives the packet transmitted from the master node; a packet filter unit that calculates as a value of delay of the packet a difference between a TS on the clock of the slave node when the packet is received and the TS of the packet received, corrects the value of the delay of the packet or a threthold for the delay of the packet, and performs filter processing on the packet received from the packet receiving unit based on the value of the delay of the packet and the threshold for the delay of the packet; and a phase synchronization unit that outputs the clock of the slave node based on the TS included in the packet employed.

Abstract: Between a first pair of termination nodes, a first current-use packet transmission path and at least one first spare packet transmission path are defined. Between a second pair of termination nodes, a second current-use packet transmission path and at least one second spare packet transmission path are defined. When no network fault occurs, packets are transmitted between the pairs of nodes in a 1:1 transfer mode in which the pairs transfer packets via both current-use packet transmission paths only. When a network fault occurs in the first current-use packet transmission path, both transmissions are switched from a 1:1 transfer mode to a 1+1 transfer mode, in which the first pair of nodes transfer packets by using the first current-use packet transmission path and the first spare packet transmission path, and the second pair transfer packets by using the second current-use packet transmission path and the second spare packet transmission path.

Abstract: The clock synchronization accuracy between a master node and a slave node is stably measured. The slave node synchronizes its own clock with the clock of the master node by means of the packets transmitted from the master node. It reproduces the clock of the slave node by means of the transmitted packets, accumulates information on the transmitted packets and the clock of the slave node and performs clock synchronization on the basis of the accumulated information.

Abstract: Provided in the EoE technique are the node, the network, the correspondence relationship generating method and the frame transfer program to avoid traffic concentration on a specific link to improve throughput of the network as a whole by realizing optimum path transfer. The frame switching unit includes the frame analysis unit for analyzing an input frame kind and the like, the table search unit for obtaining frame rewriting information and output port information, the forwarding table storage unit for managing an output port of a frame, the MAC learning unit for executing MAC address learning, the EoE-MAC learning unit for learning a relationship between a MAC address and an EoE-MAC address, the STP control unit for executing processing of a spanning tree, and the like.

Abstract: The present invention measures 1-way delay without equipping all nodes with special functionality in a situation in which time has not been synchronized. The delay measurement system of the present invention has a transmission origin node and a transmission destination node which is connected to the transmission origin node through a network including relay nodes, and measures the delay time from the transmission origin node to the transmission destination node direction, wherein the transmission origin node generates a clock. On the basis of the generated clock, delay measurement packets are generated at regular periods. The generated delay measurement packets are transmitted to the transmission destination node. The transmission destination node selects the delay measurement packets from among the received frames. The delay received by the delay measurement packets in the network between the transmission origin node to the node itself is measured.

Abstract: To provide a communication apparatus and a packetization period change method that allow a packetization period/TDM period to change during a service of a TDM-PW system without affecting the service traffic, there is provided a communication apparatus that receives packetized data converted from TDM data, including a period information detection unit, a jitter buffer that stores the packetized data for a certain period of time, and a jitter buffer capacity control unit. The period information detection unit extracts packetization period information indicating a period to packetize TDM data contained in the received packetized data and acquires a TDM period to time-division multiplex the packetized data based on the packetization period information. The jitter buffer capacity control unit receives the acquired TDM period and controls a capacity of the jitter buffer in accordance with the TDM period.

Abstract: [Issues] To provide a node (transfer device) which can process an OAM frame within an output line card. [Solution Method] A node according to the present invention is used in an MPLS (Multi Protocol Label Switching) network, and the node includes an input unit which receives an OAM (Operation Administration and Maintenance) frame including TTL (Time To Live) from outside of the node and an output unit which transmits an OAM frame to outside of the node, wherein the input unit sets the TTL to a specific value and transmits the received OAM frame to the output unit in case a termination destination which an OAM frame received from outside indicates is the node and the received OAM frame is to be transmitted to the output unit and the output unit terminates an OAM frame transmitted from the input unit.

Abstract: The frame switching unit 630 has the frame analysis unit 700, the frame rewriting unit 710, the frame transfer unit 720, the table search unit 730, the forwarding table 740, the MAC learning unit 750, the control frame distribution unit 760, the setting control unit 790, the STP control unit 780 which, when receiving a topology change message, converts an LT flag from 0 to 1 to indicate an entry as of before switching to leave the entry in the table, and the OAM control unit 770 which, upon an LT execution request before failure switching, transfers an LT frame according an output port in an entry whose LT flag is 1 among entries in the forwarding table 740.

Abstract: An inspection signal to inspect forward-path or return-path communication, is transmitted from a reference node of a network. A response signal is transmitted in a priority class from a node of a forward path to the reference node. In the case of inspection of return-path communication, a replica of the response signal is transmitted in a non-priority class from the node of the forward path to the return path, and the node that receives the replica of the response signal transfers the replica in a priority class to the reference node. In the case of inspection of forward-path communication, a replica of the inspection signal is transmitted in a non-priority class from the node of the forward path to the forward path, and a replica of the response signal is transmitted in a priority class from the node that receives a replica of the inspection signal to the reference node.

Abstract: A packet transmission system includes a plurality of nodes connected by a packet transmission path. A current-use packet transmission path is used as the packet transmission path when a fault does not occur, and a spare packet transmission path is used as the packet transmission path when the fault has occurred.

Abstract: A communication apparatus including: a counter storage unit storing a reception counter value of the apparatus when a specific frame is received; a measurement unit measuring the number of frame losses occurring between the apparatus and the preceding apparatus on the basis of the reception counter value of the apparatus, a transmission counter value of a source apparatus of the specific frame included in the specific frame and the total number of frame losses between the source apparatus and the preceding apparatus of the apparatus, when the specific frame is received; a transmission unit transmitting the specific frame; and a frame control unit adding, to the specific frame, loss information associating the number of frame losses occurring between the apparatus and the preceding apparatus with an identifier of the apparatus and forwarding the specific frame to the transmission unit, when the frame loss occurs, and forwarding the specific frame to the transmission unit without adding the loss information to

Abstract: For eliminating a reduction in throughput in a network as a whole according to optimum path transfer technique which is the expansion of spanning tree protocol, a frame switching unit of the network has an STP control unit for, when a port state of a spanning tree is changed, notifying a table control unit of an identifier of the spanning tree and a port number of a predetermined port among the respective ports, the table control unit for setting, in a forwarding table storage unit, a received port number of a predetermined port as an output port in an entry in which a node ID is equivalent to a spanning tree identifier, and a table search unit for determining an output destination from among output ports obtained by acquisition of received frame information from a frame analysis unit.