Patent ID: 7861080

Claim:
A packet communication system for performing packet communication, comprising: a packet transmission apparatus; and a packet receiving apparatus, the packet transmission apparatus comprising: a transmission security policy database to store a security policy indicating a level of protection applied to a packet, and to specify the omission of header information attached when a transmission packet is capsulated, as a transmission security policy for omitting redundant information; a header-information omitting section to search the transmission security policy database at packet transmission for a security policy for a capsulated transmission packet, and, when recognizing that the capsulated transmission packet is a target packet from which the header information is to be omitted, to omit the header information from the target packet; and a packet transmission processing section to add a security header by tunneling in an encryption protocol and a header for tunnel communication to the packet from which the header information has been omitted, and to apply transmission processing to the packet changed from a triple header capsulation to a double header capsulation, and the packet receiving apparatus comprising: a receiving security policy database to specify the header information, which is to be recovered, as a receiving security policy; and a header-information recovering section to search the receiving security policy database at packet reception for a security policy for a received packet, and, when recognizing that the received packet is a target packet from which the header information has been omitted, to recover the header information, and to change from the double header capsulation to the triple header capsulation.