To provide a scheduling technology that satisfies a QoS condition by a probability theory.

Packet scheduling is made for transmission through a communication link in a network employing an LWDF(largest weighting delay first) scheduling system. The method of this invention includes a step a) where a delay of a plurality of packets including at least one each of packets stored in a plurality of queues is calculated, and a step b) where an optional packet is selected for the transmission among a plurality of the packets on the basis of comparison between the delays that are at least partially calculated and weighted. One node in a communication network calculates a delay of one optional packet as a difference between a current time and the arrival time of the optional packet. A plurality (N) of packets relates to a corresponding data flow in N-sets of data flows and each packet is placed at a corresponding head position of N sets of the queues.