Patent ID: 7408879

Claim:
A router, comprising: a clock configured to be synchronous to a transmission terminal that transmits a route setup packet and a data packet and to provide a current time; a propagation delay time calculating unit configured to calculate a propagation delay time; an acceptable delay time calculating unit configured to calculate an acceptable delay time by use of acceptable delay time information and the propagation delay time; a comparator configured to compare a delay time of the data packet with the acceptable delay time calculated by the acceptable delay time calculating unit; and a packet processing unit configured to either transfer or discard the data packet based on the comparison result of the comparator, wherein the route setup packet is used when setting up a route to transfer the data packet and includes a delay variance and a source departure time of the route setup packet as the acceptable delay time information, the source departure time of the route setup packet indicates a time that the transmission terminal transmits the route setup packet, the propagation delay time calculating unit calculates the propagation delay time by use of the source departure time of the route setup packet and the current time obtained from the clock, and the acceptable delay time calculating unit calculates the acceptable delay time of the data packet by adding together the delay variance and the propagation delay time.