Abstract: A communication system includes a probe transmission server 3 which transmits at fixed intervals of time a probe multicast packet distributed along the same path as a main multicast packet, a delay insertion server 5 which appends the same fixed delay time to each of the main multicast packet and the probe multicast packet, a backup server 2 which generates synchronism and delay backup multicast packets from the main multicast packet and transmits them, and a communication control device 7 which determines the communication of the main multicast packet based on a reception interval of the probe multicast packet, generates a backup main multicast packet from the backup multicast packet when a communication break is detected, and transmits it. The communication system, upon implementing a broadcast-type multicast service, enhances compensation of communication breaks when detecting and recovering from a fault in an IP network, and reduces the network traffic.

Abstract: In order to distribute multicast packets, using different multicast addresses and avoiding fault points, a backup server is installed close to a master and converts backup multicast packets and sends them as master multicast packets to the client. At this time, backup multicast packets are delayed and sent while the delay is determined from an allowable retransmission time, a one-direction delay to the client, a time required to detect linkage problems, and a time required to establish backup paths and so on.

Abstract: A communication path control system includes a storage device which stores data of paths between communication nodes; and a communication path selecting device which selects a path candidate for setting a new communication path among path candidates, each of which can be provided as a communication path between the communication nodes. Based on the data of paths, the communication path selecting device obtains MAX(PN) for each of the path candidates P1, . . . , Pn, n being an integer of 2 or larger, where MAX(PN) is the maximum value of the number PN of already-established communication paths passing through each link which forms said each path candidate, that is, PN=[N1, . . . , Nm], is an integer of 1 or larger, and N is the number of the already-established communication paths passing through said each link; and the communication path selecting device selects the path candidate having the smallest value among the maximum values MAX(PN) of the path candidates.

Abstract: A channel-switching multicast distribution apparatus in a system for providing channels by multicast. The apparatus includes a device for receiving multicast data of a first multicast group for a first channel; a device for storing the received multicast data; a delaying device for reading the stored multicast data, and delaying the data by a predetermined time; and a transmission device for transmitting the delayed data through a second multicast group for performing channel switching so as to select the first channel. Instead of the delaying device and the transmission device, a data rearranging device for reading the stored multicast data, and rearranging the data so as to change the order of packets thereof; and a transmission device for transmitting the rearranged data through a second multicast group for performing channel switching so as to select the first channel may be provided.

Abstract: A communication system includes a probe transmission server 3 which transmits at fixed intervals of time a probe multicast packet distributed along the same path as a main multicast packet, a delay insertion server 5 which appends the same fixed delay time to each of the main multicast packet and the probe multicast packet, a backup server 2 which generates synchronism and delay backup multicast packets from the main multicast packet and transmits them, and a communication control device 7 which determines the communication of the main multicast packet based on a reception interval of the probe multicast packet, generates a backup main multicast packet from the backup multicast packet when a communication break is detected, and transmits it. The communication system, upon implementing a broadcast-type multicast service, enhances compensation of communication breaks when detecting and recovering from a fault in an IP network, and reduces the network traffic.

Abstract: A communication system includes a probe transmission server 3 which transmits at fixed intervals of time a probe multicast packet distributed along the same path as a main multicast packet, a delay insertion server 5 which appends the same fixed delay time to each of the main multicast packet and the probe multicast packet, a backup server 2 which generates synchronism and delay backup multicast packets from the main multicast packet and transmits them, and a communication control device 7 which determines the communication of the main multicast packet based on a reception interval of the probe multicast packet, generates a backup main multicast packet from the backup multicast packet when a communication break is detected, and transmits it. The communication system, upon implementing a broadcast-type multicast service, enhances compensation of communication breaks when detecting and recovering from a fault in an IP network, and reduces the network traffic.

Abstract: In order to distribute multicast packets, using different multicast addresses and avoiding fault points, a backup server is installed close to a master and converts backup multicast packets and sends them as master multicast packets to the client. At this time, backup multicast packets are delayed and sent while the delay is determined from an allowable retransmission time, a one-direction delay to the client, a time required to detect linkage problems, and a time required to establish backup paths and so on.

Abstract: A communication path control system includes a storage device which stores data of paths between communication nodes; and a communication path selecting device which selects a path candidate for setting a new communication path among path candidates, each of which can be provided as a communication path between the communication nodes. Based on the data of paths, the communication path selecting device obtains MAX(PN) for each of the path candidates Pl, . . . , Pn, n being an integer of 2 or larger, where MAX(PN) is the maximum value of the number PN of already-established communication paths passing through each link which forms said each path candidate, that is, PN=[Nl, . . . , Nm], is an integer of 1 or larger, and N is the number of the already-established communication paths passing through said each link; and the communication path selecting device selects the path candidate having the smallest value among the maximum values MAX(PN) of the path candidates.

Abstract: A communication system includes: a probe transmission server which transmits packets of a probe multicast at certain intervals on a same path as that of a main multicast; an aggregation server which converts multiple main cast and the probe multi cast into an aggregative multicast; and a communication control apparatus which determines an overall communication condition of the packets of the main multicast based on intervals of the probe multicast, wherein the communication control apparatus receives and recovers the packet of the main multicast from the packet of the aggregative multicast, if a communication break of the main multicast is detected.

Abstract: A channel-switching multicast distribution apparatus in a system for providing channels by multicast. The apparatus includes a device for receiving multicast data of a first multicast group for a first channel; a device for storing the received multicast data; a delaying device for reading the stored multicast data, and delaying the data by a predetermined time; and a transmission device for transmitting the delayed data through a second multicast group for performing channel switching so as to select the first channel. Instead of the delaying device and the transmission device, a data rearranging device for reading the stored multicast data, and rearranging the data so as to change the order of packets thereof; and a transmission device for transmitting the rearranged data through a second multicast group for performing channel switching so as to select the first channel may be provided.

Abstract: Data of traffic with long-range dependence characteristics is generated by a host terminal and transferred to a memory arranged on a board. The memory stores the traffic data comprising at least one of the number of IP packets output per unit time and total number of bytes, a set value of each parameter of the generated IP packets (i.e., packet length table) and an IP address table. A packet generation section refers to the data in the memory to generate traffic with long-range dependence characteristics at a speed corresponding to a high-speed network. As a result, the behavior of the network at the time of application of the load can be measured before the actual use of the network. According to the present invention, a traffic generation apparatus that can supply the actual network with a load close to the real traffic can be provided.

Abstract: A communication system includes: a probe transmission server which transmits packets of a probe multicast at certain intervals on a same path as that of a main multicast; an aggregation server which converts multiple main cast and the probe multi cast into an aggregative multicast; and a communication control apparatus which determines an overall communication condition of the packets of the main multicast based on intervals of the probe multicast, wherein the communication control apparatus receives and recovers the packet of the main multicast from the packet of the aggregative multicast, if a communication break of the main multicast is detected.

Abstract: A communication system includes a probe transmission server 3 which transmits at fixed intervals of time a probe multicast packet distributed along the same path as a main multicast packet, a delay insertion server 5 which appends the same fixed delay time to each of the main multicast packet and the probe multicast packet, a backup server 2 which generates synchronism and delay backup multicast packets from the main multicast packet and transmits them, and a communication control device 7 which determines the communication of the main multicast packet based on a reception interval of the probe multicast packet, generates a backup main multicast packet from the backup multicast packet when a communication break is detected, and transmits it. The communication system, upon implementing a broadcast-type multicast service, enhances compensation of communication breaks when detecting and recovering from a fault in an IP network, and reduces the network traffic.

Abstract: In order to distribute multicast packets, using different multicast addresses and avoiding fault points, a backup server is installed close to a master and converts backup multicast packets and sends them as master multicast packets to the client. At this time, backup multicast packets are delayed and sent while the delay is determined from an allowable retransmission time, a one-direction delay to the client, a time required to detect linkage problems, and a time required to establish backup paths and so on.

Abstract: This present invention provides a traffic control system which adapts a P2P traffic to the circuit capacity and topology of a physical network. In a traffic control portion, a correspondent node identifying portion monitors the header of a packet exchanged by each P2P traffic and identifies the attribute of a correspondent node. A monitoring object extracting portion extracts a P2P connection based on the identification result. A traffic amount measuring portion obtains the total amount of each P2P traffic which is a monitoring object. A connection selecting portion selects a connection which should be shut down based on the total traffic amount. A filter portion shuts down the shut-down object connection selected by the connection selecting portion of the traffic monitoring portion.

Abstract: An L2 switch disposed between a multicast network and one or more user systems includes a switching engine having an input port to receive multicasted data from the multicast network and a plurality of output ports, the switching engine capable of delivering at least a part of the multicasted data from at least one of a plurality of data sources in the multicast network to one or more data-destination ports of the plurality of output ports; a transfer table to store corresponding relations between the at least one of the plurality of data sources and the one or more data-destination ports of the plurality of output ports; and a switching controller to update the transfer table according to a predetermined message that passes through the switching engine and to control the delivering of the multicasted data of the switching engine by referring to the transfer table.

Abstract: The apparatus 10 is set on the line between the first and second computers 1,2 which respectively communicates by a protocol, such as TCP, having a flow control. The delay between the first computer 1 and a position, at which the apparatus 10 is set, is less than the delay between the position and the second computer 2. The apparatus 10 sends and receives a packet to/from the computers 1,2. The apparatus 10 transfers to the second computer 2, a data packet sent from the first computer 1 and being larger than a maximum data amount notified by the second computer 2. The apparatus 10 transfers, to the first computer 1, a data packet sent from the second computer 2, but does not transfer, to the first computer 1, an ACK packet sent from the second computer 2. The apparatus 10 generates, instead of the second computer 2, an ACK packet for a data packet sent from the first computer 1 and then sends the ACK packet to the first computer 1.

Abstract: A TCP gateway terminates TCP flow control and retransmission control of TCP packets which are input from a transmitter side terminal, in place of a receiver side terminal. Also, the TCP gateway transfers the packet to the TCP gateway which is located on the opposite side, by using selective retransmission procedures in a data link layer using SSCOP and by using peculiar flow control procedures. In addition, the TCP gateway provides the process of transferring the packet to the receiver side terminal in accordance with the TCP process procedures in place of the transmitter side terminal, to a plurality of TCP connections simultaneously.

Abstract: A packet repeater (e.g., gateway) is applicable to an integrated digital network system which incorporates a first network (e.g., Internet) and a second network (e.g., satellite communication system) comprising an upstream line and a downstream line which are asymmetrical with respect to each other in data transmission speed. In the packet repeater, specific data (e.g., TCP data) are extracted from plural packets and are assembled together into a single transmission packet on the basis of the maximal amount of storable data, which is greater than the maximal segment size notified from a receiver under conditions in which the reception window size fulfills the maximal amount of storable data.

Abstract: Data of traffic with long-range dependence characteristics is generated by a host terminal and transferred to a memory arranged on a board. The memory stores the traffic data comprising at least one of the number of IP packets output per unit time and total number of bytes, a set value of each parameter of the generated IP packets (i.e., packet length table) and an IP address table. A packet generation section refers to the data in the memory to generate traffic with long-range dependence characteristics at a speed corresponding to a high-speed network. As a result, the behavior of the network at the time of application of the load can be measured before the actual use of the network. According to the present invention, a traffic generation apparatus that can supply the actual network with a load close to the real traffic can be provided.