Patent ID: 7903689

Claim:
A control method of a communication system, comprising: dividing a primary packet of an Internet Protocol (IP) output from a first information processor at a transmitting side into a plurality of secondary packets of said IP in a first communication controller at said transmitting side; sending said plurality of secondary packets to a network by said first communication controller; receiving said plurality of secondary packets in a second communication controller at a receiving side; generating, in said second communication controller, a reassembly header with an IP header and a Transmission Control Protocol (TCP) header for processing said primary packet to be reassembled, where said generating is performed by: calculating a length of said primary packet to be reassembled using information included in a last one of said plurality of secondary packets that is last in order of said dividing, where said information includes a packet length and a fragment offset of said last one of said plurality of secondary packets, obtaining said TCP header included in an initial one of said plurality of secondary packets that is initial in order of said dividing, and putting, in said reassembly header, both said IP header whose total length is set to said calculated length and said TCP header; sending said reassembly header from said second communication controller to a second information processor at said receiving side; executing, at said second information processor, protocol processing that includes analyzing said reassembly header to analyze the contents of said IP and TCP headers included in said reassembly header; temporarily storing a result of said protocol processing in said second information processor; reassembling said plurality of secondary packets into said primary packet in said second communication controller in parallel with said executing; upon completion of said reassembling, sending said reassembled primary packet from said second communication controller to said second information processor and allowing, at said second information processor, said temporarily stored result of said protocol processing to be reflected in a status of said protocol processing, wherein said protocol processing includes: checking a size of said TCP header and a size of said IP header, verification of a header checksum of said IP header, identifying a connection in accordance with a determination of a source-destination port pair of a TCP session, determination of whether received data is within volume of a receive window, said determination being made from a sequence number field of said TCP header and a data size of said primary packet, or reading an acknowledgement number field of said TCP header in said received primary packet to recognize a status of reverse stream transfer, or any combination thereof.