Patent ID: 7447164

Claim:
A communication apparatus having a network device connected to a network to be used for outputting and receiving packets to and from said network, said communication apparatus comprising: time measurement means for measuring a time on the basis of a clock signal having a predetermined frequency; transmission process means for receiving information data from an application at a higher level, packetizing said information data, outputting the packet to said network by way of said network device and saving sender information including a transmission time of said packet, wherein said saved sender information remains saved after said packet is output to said network; reception process means for receiving a predetermined packet from said network by way of said network device, generating receiver information including an arrival time of said packet by using said time measurement means, saving said receiver information, depacketizing said packet to obtain predetermined information data and outputting said predetermined information data to an application at a higher level; and data control means for controlling flows of said information data; wherein said reception process means includes correction means for: comparing transmission-time information included in a received packet as a transmission point of time measured for said packet by the time measurement means of the transmitting communication apparatus with time information showing a point of time measured as an arrival time of said packet by said time measurement means; and correcting said time measurement means so as to synchronize said time measurement means of a transmitting communication apparatus on the basis of said transmission-time information in case that a difference between said transmission point of time and said arrival time is beyond a predetermined range.