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.

Abstract: An exemplary object of the present invention lies in a point of providing a technology capable of measuring a transmission quality of an Ethernet network in order to utilize Ethernet as carrier-grade communication. The present invention includes an error bit number measurer for measuring the number of error bits that have occurred for a frame of Ethernet, being a target of monitoring, within a monitoring period, a transmitted bit number measurer for measuring the number of total transmitted bits of Ethernet frames that a device facing it has transmitted within the foregoing monitoring period, and a bit error rate operator for obtaining a bit error rate of a transmission path by employing a measurement result by the foregoing error bit number measurer and the foregoing transmitted bit number measurer.

Abstract: [Problems to be solved] To provide a system capable of controlling a PC firewall responding to a location, thereby to prevent a third person from intruding into a PC without being restricted by an application. [Means to solve the problems] A first security system includes: a network recognizing unit for performing a test for confirming whether an IP address allotted to the PC coincides with a specification value, and notifying its test result to a security setting unit; the security setting unit for, upon receipt of the test result from the network recognizing unit, notifying a setting modification command to a firewall unit based upon its test result; and the firewall unit for, upon receipt of the setting modification command from the security setting unit, executing a packet filtering responding to its command.

Abstract: In a communication system in which a plurality of communication terminals sequentially transfer data to a server during the respective transmission permissible periods assigned to the respective communication terminals, the communication terminal transfers a preamble for synchronization to the server at a time of starting the transmission permissible period, converts a data frame for every 8 bits into every 10 bit-code, and transmits to the server, the signal string with a code indicating the head added there, during the transmission permissible period, and turns a communication to the server into a zero signal state, during a period other than the transmission permissible period, while the server establishes a synchronization by reading the preamble for synchronization inserted into the signal string received from each of the communication terminals, converts a portion of the zero signal state of the signal string into a predetermined special code string, and inversely transforms the received signal string i

Abstract: A mobile terminal includes a mobile phone function unit, a storing unit, a communication control unit, and a store-and-forward multihop communication function unit. The mobile phone function unit confirms status of connection with a mobile base station and exchanges information with the mobile base station when the status of connection is a connection state. The storing unit stores information received and generated by the mobile phone function unit. The communication control unit receives connection information including the status of connection from the mobile phone function unit and generates a control signal when the connection information indicates a disconnection state.

Abstract: A system includes a storage for storing positional information of telephone terminals, a determiner for being notified of a called telephone terminal by an exchange which received a call from a calling telephone terminal, and determining whether the called telephone terminal is in a particular area, and an indicator for, if the called telephone terminal is in the area, retrieving a telephone terminal in a range based on the called telephone terminal, as a neighboring terminal, and indicating the neighboring terminal to the exchange. The exchange includes a requester for sending a connection request to another exchange, to request that a connection be made between the called telephone terminal and the neighboring terminal, and a caller for receiving a connection request from another exchange and sending a call to a telephone terminal which is assigned by the connection request.

Abstract: A clock synchronization system includes a master node; a PSN (Packet Switched Network); and a slave node configured to synchronize a recovery clock signal in the slave node with a clock signal in the master node by using packets periodically received from the master node through the PSN.

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: In a multi-ring network with a plurality of rings to which RPR is applied connected, high-speed failure recovery is enabled when a failure occurs between the rings. The contact nodes 700-1 and 700-3 connected to the living inter-link 505 periodically transmit and receive a KeepAlive signal to/from each other. Then, when a KeepAlive signal fails to arrive for a fixed time period, determination is made that the inter-link 505 develops a fault to broadcast-transmit an inter-link failure notification RPR-MAC frame indicative of failure occurrence on the inter-link to each node. A contact node as a transmission source of the inter-link failure notification RPR-MAC frame and each node having received the inter-link failure notification RPR-MAC frame immediately flush learning contents of their own learning data bases. A contact node connected to the spare inter-link 506 switches the spare inter-link 506 to a forwarding state.

Abstract: [Problems] To enable each of a plurality of links connecting rings to perform packet transfer while preventing multiple reception of packets and broadcast stream in a normal state where no failure has occurred. [Means for Solving Problems] An inter-ring connecting node 101a and an inter-ring connecting node 102a are connected, and similarly, an inter-ring connecting node 101b and the inter-ring connecting node 102b are connected. When each of the inter-ring connecting nodes 102a and 102b receives a packet to be broadcasted via a link 103 or 104, it performs bidirectional flooding of the broadcast packet such that the packet arrives at a predetermined cleave point. At this time, each of the inter-ring connecting nodes 102a and 102b uses the source address of the other node so as to falsify the source.

Abstract: An object of the present invention is to reflect a band of the bottleneck into the cost, to select an optimal path, and to enhance an efficiency of the net utilization without making a setting or a modification to the apparatus (bridge etc.) in which the path control protocol operates in a case where a difference exists between an actually utilizable rate (a band of the bottleneck) in the path between the bridges etc. and a link rate of the connection link such as the bridge etc. in a net in which the apparatus (bridge etc.), in which the path control protocol (STP etc.) for automatically computing a cost of a link by a physical band of the connection link operates, exists.

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 invention enables protection of a ring frame transferred via an inter-ring bridge ring node when a fault occurs at the node in a multiring. Ring nodes form a ring protection domain to enable one ring node to be bypassed by using other ring nodes when a fault occurs at this ring node. The TTL value of ring frame to be transferred through the bypass is set to a value obtained by adding the number of hops h to the faulty ring node to a common initial value A in the same two-fiber ring to enable detection of a characteristic TTL value at a bypassing ring node. The bypass for the ring frame is selected with reference to the characteristic TTL value at the bypassing ring node.

Abstract: Two transmission devices connected to a link in which a failure occurs turn back a ring. Other transmission device changes a transmission ring of an NNI packet which is a UNI packet whose transmission source is its own transmission device and which had been transmitted through the link before the failure occurs to have a reverse direction. In addition, each transmission device, upon receiving an NNI packet whose transmission destination NNI address is one or any one of a plurality of NNI addresses applied to its own transmission device, outputs the packet to a self-owned tributary port irrespectively of whether it is sent through an inner ring or an outer ring.

Abstract: The invention enables protection of a ring frame transferred via an inter-ring bridge ring node when a fault occurs at the node in a multiring. Ring nodes form a ring protection domain to enable one ring node to be bypassed by using other ring nodes when a fault occurs at this ring node. The TTL value of ring frame to be transferred through the bypass is set to a value obtained by adding the number of hops h to the faulty ring node to a common initial value A in the same two-fiber ring to enable detection of a characteristic TTL value at a bypassing ring node. The bypass fur the ring frame is selected with reference to the characteristic TTL value at the bypassing ring node.

Abstract: An object of the present application is to provide a technology that can achieve packet communication between terminals connected to the Internet by way of a relay server in a faster and safer manner. The system of present application is a communication system characterized in that, on receipt of a start-connection message, a relay server having the lowest load is searched, and communication is achieved by way of the relay server found.

Abstract: An object of the present invention is to provide a technology capable of estimating header conversion applied in a network by collecting information required in the estimation, without introducing a special-purpose server directed to estimate header conversion applied in the network. The present invention provides a system for estimating information about apparatuses on a network using an error message or control message sent in response to a transmitted packet as stipulated by a communication protocol to estimate information about apparatuses on the network.

Abstract: A communication system includes a server and a plurality of terminals. The server repeatedly assigns transmission periods to the terminals in a regular order, each of the terminals being permitted as a current terminal to transmit data stored in a buffer thereof to the server during an assigned transmission period assigned thereto by the server as a current transmission period. The communication system includes: a transmission controller provided in each of the terminals for transmitting a release request notification to the server in a case where the terminal finishes data transmission before the end of the assigned transmission period assigned to the terminal, and a transmission period assigning portion provided in the server for assigning a next transmission period following the current transmission period to a next terminal different from the current terminal, in response to the release request notification.

Abstract: A storage circuit defines a first field for storing first header bits of a first payload signal of a first data unit, a second field, and a third field for storing the first payload signal. The first header bits are equal in number to second header bits of a second payload signal of a second data unit. A division circuit divides the first header bits by a generator polynomial to produce a first error check code. The same generator polynomial is used to divide the second header bits to produce a second error check code. A remainder of division of hypothetical header bits by the generator polynomial is summed to the first error check code to produce a sum which is inserted into the second field of the storage circuit. The hypothetical header bits are greater in number than a total number of bits in the first and second fields, so that the first and second data units can be distinguished from each other by different error check results of the first and second data units.

Abstract: A storage circuit defines a first field for storing first header bits of a first payload signal of a first data unit, a second field, and a third field for storing the first payload signal. The first header bits are equal in number to second header bits of a second payload signal of a second data unit. A division circuit divides the first header bits by a generator polynomial to produce a first error check code. The same generator polynomial is used to divide the second header bits to produce a second error check code. A remainder of division of hypothetical header bits by the generator polynomial is summed to the first error check code to produce a sum which is inserted into the second field of the storage circuit. The hypothetical header bits are greater in number than a total number of bits in the first and second fields, so that the first and second data units can be distinguished from each other by different error check results of the first and second data units.