TCP relay apparatus

A method used in a transmission control protocol (TCP) relay apparatus for relaying TCP communication performed between a client device and a server device which are linked to respective networks having different characteristics, the apparatus including a TCP processing unit for performing TCP connection and data transmission/reception control, a network interface processing unit for controlling a network interface device which performs data transmission/reception with respect to a network, an internet protocol (IP) processing unit for performing IP layer processing, for having therein an output queue and for performing, upon transmission of IP packets to the network interface processing unit, IP packet queuing until completion of the transmissions,

• a TCP relay processing unit for performing termination and relay processing for TCP communication between the client device and the server device, a socket application programming interface (API) processing unit for providing the TCP processing unit with an API used for connection establishment and/or data transmission/reception, and a TCP information management region for use in storage of information used for TCP management and control, including a default TCP set-up storing therein default TCP set-up information;
• wherein
• the TCP information management region has a socket parameter management table and a custom TCP setup,
• the socket parameter management table includes, as socket set-up information, a socket descriptor field “A,” a classification field A, a minimum retransmission timeout (RTO) period value field A, a maximum RTO period value field A and an initial window size field A,
• the socket descriptor field A is a region for storage of a socket identifier created by the TCP relay processing unit, the classification field A is a region for storage of a network type or types,
• the minimum RTO period value filed A is a region for storage of a minimum value (lower limit value) of RTO period, The maximum RTO period value field A is a region for storage of a maximum value (upper limit value) of RTO period, The initial window size field A is a region for storage of an initial window size value, the custom TCP setup includes a classification field “B”, a minimum RTO period value field B, a maximum RTO period value field B and an initial window size filed B, the classification field B is a region for storage of network types,
• the minimum RTO period value field B is a region for storage of a minimum value (lower limit value) of RTO period, the maximum RTO period value filed B is a region for storage of a maximum value (upper limit value) of RTO period, and
• the initial window size field B is a region for storage of an initial window size value, and
• a unit for setting, in units of TCP connections, TCP control information suitable for the characteristic of the networks being linked with the client device and the server device respectively,
• the method comprises the steps of, at the TCP relay processing unit:
• determining whether the TCP connection is a custom object, upon receipt of a TCP connection from the client device at a listen port;
• searching the custom TCP setup while using as a search key the type of a network to which the client device at a TCP connection destination belongs;
• when the TCP connection is custom object, thereby obtaining information of the custom TCP setup from an entry matched by the search;
• determining whether the TCP connection is a custom object, upon execution of TCP connection with the server device;
• searching the custom TCP setup while using as a search key the type of the network to which the server device at a TCP connection destination belongs, when the TCP connection is custom object, thereby acquiring information of the custom TCP setup from an entry matched by the search;
• and registering network type information and the custom TCP setup information to an entry indicating the TCP setup of the socket parameter management table.