Abstract: A network priority determining system in which the percentage of utilization of the network transmission medium is significantly increased and the number and complexity of hardware components is reduced. When the network is not being used for transmission of data packets, a free token is circulated having a priority controlling field and a reservation field, while when the network is to be used for transmission, a busy token is circulated. To begin transmission, a network can catch a free packet if its priority level is equal to or less than that of the free token. The reservation field value and priority field value contained in the free token may be set in accordance with a reservation value of the previously circulated busy token.