Abstract: A communication system includes a data sending terminal which sends data and a data receiving terminal which sends an acknowledgement, which indicates that the data is received, to the data sending terminal in reply to receiving the data, and the data receiving terminal includes a unit which judges whether it is necessary to resend the acknowledgement on the basis of judgment whether the data receiving terminal receives new data from the data sending terminal within a predetermined time since sending the acknowledgement.

Abstract: A mapping server includes: a path information obtaining unit that obtains path information on external networks through a forwarding device connected to an external network; and a mapping information generating unit that generates mapping information that relates the path information and the forwarding device.

Abstract: A high-speed communication system according to the present invention includes: a plurality of nodes disposed on a communication path; and a plurality of communication connections established between the plurality of nodes. The plurality of nodes exchange a plurality of pieces of performance model information between the nodes, the plurality of pieces of performance model information representing communication performances achievable by each of the plurality of communication connections. Each of the plurality of nodes executes communication control based on any one of the plurality of pieces of performance model information.

Abstract: A communication quality monitoring device is provided which determines communication quality deterioration by variation of a transmission buffer length in session control irrespectively of generation/non-generation of a data loss. A packet transmission and quality monitoring device 11-1 which detects deterioration in communication quality based on a buffer length of a session control protocol includes a threshold value calculating unit 11-17 which calculates a threshold value for the determination of deterioration in communication quality according to a parameter related to congestion detection of the session control protocol, and a deterioration determining unit 11-18 which determines deterioration in communication quality by comparing the threshold value and the buffer length.

Abstract: A communication system includes a data sending terminal which sends data and a data receiving terminal which sends an acknowledgement, which indicates that the data is received, to the data sending terminal in reply to receiving the data, and the data receiving terminal includes a unit which judges whether it is necessary to resend the acknowledgement on the basis of judgment whether the data receiving terminal receives new data from the data sending terminal within a predetermined time since sending the acknowledgement.

Abstract: A path control apparatus of the present invention includes: a status change detecting unit that detects a status change of a network; a path calculating unit that decides a path in accordance with the status of the network; and a calculation execution node deciding unit that compares a shortest path tree, which is established before occurrence of a change in the status of the network calculated by the path calculating unit, with a shortest path tree, which is established after the occurrence of the change in the status of the network calculated by the path calculating unit, and creates information required for determining whether a node apparatus in the network needs a path update, when the change occurs in the status of the network.

Abstract: A topology detection apparatus includes, in a network having a tree-type topology: a route overlap judgment part that judges an existence or non-existence of an overlap between: a first route between terminals whose connection position are known; and a second route between a terminal whose connection position is known and a terminal whose connection position is unknown; and a topology detection part which determines the network topology based on the existence or non-existence of the first route and the second route.

Abstract: A path control method includes a procedure for developing a path control message including regional information in transmission on the network. The regional information designates a path and/or a path length for transmitting the path control message. The path control message includes a regional property for instructing each node as to how to process the regional information either in a strict manner or in a flexible manner. With reference to the regional information and/or the regional property, each node is capable of selecting a destination node to which the path control message is to be transmitted, stopping the further transmission of the path control message, or discarding the path control message.

Abstract: A mapping server includes: a path information obtaining unit that obtains path information on external networks through a forwarding device connected to an external network; and a mapping information generating unit that generates mapping information that relates the path information and the forwarding device.

Abstract: A protocol process to a reception traffic is executed by cluster members of a current use system and a backup system. The backup system discards the reception traffic subjected to the protocol process and only the current use system transfers the reception traffic to an AP. The AP makes an application process redundant in an independent method. The cluster member in charge of the protocol process to the reception traffic is determined by using a data in a lower layer and the cluster member in charge of the application process is determined by using a data in a higher layer after the protocol process.

Abstract: A node apparatus wherein when a topology change occurs on a network used for packet transfer between node apparatuses, the node apparatus performs dynamic route control for establishing a new normal route. The node apparatus has a device that receives, from another node apparatus, a route control message which includes information required for route determination; a device that computes a route on the network based on the received route control message; a device that sends another node apparatus a route control message which includes information required for said another node apparatus to determine a route on the network; a device wherein when receiving the route control message, this device computes an operation start time for route control operation by the route computation and the message sending, based on a distance between a topology change part and said node apparatus of oneself; and a device that controls the execution of the route control operation based on the computed operation start time.

Abstract: In order to more efficiently use port resources, which are finite global address resources assigned to an address translation device, the address translation device holds a session-port assignment table showing a correspondence between an existing session and a local endpoint (port resource) in the address translation device, and a port assignment rule indicating port usage about assignable ports. An address translation unit translates address information of a packet received according to the correspondence between the existing session and the port resource shown in the session-port assignment table, and assigns the port according to the port usage indicated by the port assignment rule for a packet for opening a new session. An assignment rule update unit changes a ratio of the port usage in the port assignment rule while the correspondence between the existing session and the port resource in the session-port assignment table is not changed.

Abstract: When a failure occurs in a link or another relay device, a route control unit updates a routing table stored in a current routing table. Upon update, it acquires inhibit target route information indicating a route likely to cause a micro-loop in the updated routing table and registers it into an inhibit target table. If route update in an adjacent relay device is completed, an inhibit control unit deletes a route in which the adjacent relay device is set as a next transfer destination from the inhibit target table. A transfer processing unit determines a transfer route of a packet based on the current routing table and, if the determined transfer route is not registered in the inhibit target table, executes transfer of the packet. A micro-loop can be thereby reliably avoided when route switching in a network system where communication between plural networks is relayed by plural relay devices.

Abstract: A routing protocol unit (11) of each node (1) in a delay tolerant network calculates the probability of distribution to the destination node based on the log of end-to-end paths to the destination node from the past to the present registered in a routing table (12). A DTN forward unit (13) of a source node determines a next hop node to be used to forward forwarding data, based on the calculated distribution probability of each node with respect to the destination node.

Abstract: A high-speed communication system according to the present invention includes: a plurality of nodes disposed on a communication path; and a plurality of communication connections established between the plurality of nodes. The plurality of nodes exchange a plurality of pieces of performance model information between the nodes, the plurality of pieces of performance model information representing communication performances achievable by each of the plurality of communication connections. Each of the plurality of nodes executes communication control based on any one of the plurality of pieces of performance model information.

Abstract: A load caused by an information sharing message in an upper layer is reduced. A node, which shares information by exchanging a message between neighboring nodes in a lower layer and an upper layer of a network, includes a unit for determining whether or not to transmit a message for information sharing in the upper layer according to the contents of a state change in the neighboring nodes detected when a state change in the neighboring nodes in the lower layer is detected.

Abstract: A topology specifying apparatus 10 according to this invention includes, in a network having a tree type network topology, a route overlap determining section 4 configured to determine existence or non-existence of an overlap between a first route to a terminal having an unknown connection node and a second route between terminals having known connection nodes; and a topology specifying section 5 configured to determine a network topology based on the existence or non-existence of the overlap of the first route and the second route.

Abstract: A QoS routing apparatus as a node of a logical network to transmit data communicated between user's terminals comprises a relay unit discriminating whether or not flows of received data are measurement flows and transmitting said received data, a quality measurement unit measuring communication quality of links connected the own apparatus using the measurement flows, a quality accuracy setting unit determining measurement accuracy of the communication qualities of the respective links and a path setting unit prescribing transmission amounts of the measurement flows to the respective links. When the path setting unit prescribes the transmission amounts of the measurement flows, it applies a higher rate to a link which has been determined a lower measurement accuracy.

Abstract: The present invention provides a traffic engineering apparatus which performs traffic engineering, including: an optimal branch point determination unit which determines an optimal branch point in a network to realize a predetermined policy; and a traffic flow regulation unit which regulates a traffic flow rate into the local node during reception of traffic based on the optimal branch point determined by the optimal branch point determination unit.

Abstract: Disclosed is a node that includes a distributed hash table generation means that generates a distributed hash table which indicates the next node to which a message is to be transferred, using a link state routing protocol, a link state information that exchange unit sends and receives link state information, and a tree delivery control unit that determines the transfer destination of the link state information so that the link state information is delivered along a tree where the source node of the link state information is a root.