Abstract: A server that relays packet data transmitted and received between a first terminal and a second terminal among plurality of terminals, includes a transfer table storing unit configured to store a transfer table in which a connection address pair, includes a first connection address and a second connection address, is registered, and a connection establishment message processing unit configured to transmit a SYN ACK message as a response message to a SYN message, upon receiving the SYN message, for establishing a TCP connection from each of the terminals. The first connection address is used to connect the server and the first terminal and the second connection address is used to connect the server and the second terminal.

Abstract: A session relay device which can reliably send a data packet resent from a source to a destination without the need for reconfiguring and dividing a segment is supplied. Session relay device 110, adapted to be disposed between terminals for transmitting and receiving data as packets to which sequence numbers representative of the order of segments to be transmitted are assigned, includes session relay section 110-3 that relays data transmitted as packets between a first session opened between session relay device 110 and a terminal on a transmission side and a second session opened between session relay device 110 and a terminal on a reception side. Session relay section 110-3 receives the retransmitted segment from a terminal on the transmission side, updates a maximum segment size of the second session with the segment size of the retransmitted segment, and transmits the retransmitted segment to a terminal on the reception side.

Abstract: A server that relays packet data transmitted and received between a first terminal and a second terminal among plurality of terminals, includes a transfer table storing unit configured to store a transfer table in which a connection address pair, includes a first connection address and a second connection address, is registered, and a connection establishment message processing unit configured to transmit a SYN ACK message as a response message to a SYN message, upon receiving the SYN message, for establishing a TCP connection from each of the terminals. The first connection address is used to connect the server and the first terminal and the second connection address is used to connect the server and the second terminal.

Abstract: A communication system includes a plurality of terminals and a server that relays packet data transmitted and received between a first terminal and a second terminal among the plurality of terminals. The server includes a connection establishment message processing unit configured to transmit a first SYN ACK message that is a response message to a first SYN message transmitted from the first terminal for establishing a TCP connection upon receiving the first SYN message from the first terminal, and an option information notifying unit configured to transmit a first TCP option information notifying message that includes first TCP option information included in the first SYN message from the first terminal and first communication destination information to indicate the second terminal as a destination of communication.

Abstract: A data communication apparatus determines whether the error type is a burst error or not based on an error occurrence state of the data received from a data transmitting apparatus and transmits error type-basis error information. The data communication apparatus receives the error type-basis error information and sets the redundancy degree of an FEC processing section based on the error rate of the errors other than a burst error.

Abstract: There is provided a communication apparatus capable of increasing throughput even when the loss rate is high, without special congestion information being notified from a network. A congestion determination section determines whether the current state is light/heavy congestion from ACK packets and the content stored in a session state storage section, and hands the processing to a network state estimation section or a normal transfer section according to the result of the determination. The network state estimation section estimates the network congestion state from ACK packets and the content stored in the session state storage section. A light/heavy congestion determination section determines whether the state is light congestion or heavy congestion from the result of the estimation by the network state estimation section, and hands the processing to a resending determination section or a heavy congestion resending section according to the result of the determination.

Abstract: A session relay apparatus includes a packet relay unit, session relay unit, storage unit, session state registration unit, and session state updating unit. Upon receiving a session initiation packet or an acknowledge packet to acknowledge the session initiation packet, the packet relay unit directly transmits the received packet to a transmission destination without rewriting the packet. The session relay unit terminates the session and relays data. The storage unit stores information of the session terminated by the session relay unit. The session state registration unit temporarily registers, in the storage unit, session information corresponding to the session whose establishment is requested upon receiving the session initiation packet. The session state updating unit defines the temporarily registered session information upon receiving the acknowledge packet. When the packet of the session with the defined session information is received, the session relay unit terminates the session and relays the data.

Abstract: An information processing system operated by an active system and a standby system can reduce the load of a status synchronizing process. In a pair of an active information processing device and a standby information processing device closest to a transmitting terminal in the information processing system, the standby information processing device is arranged closer to the transmitting terminal. In a pair of an active information processing device and a standby information processing device closest to a receiving terminal in the information processing system, the standby information processing device is arranged closer to the receiving terminal. In other pair, a standby information processing device can be arranged closer to either the transmitting terminal or the receiving terminal.