Network structure method and route determination equipment

The present invention generally relates to a network system such as Internet through which individually managed and operated networks are interconnected, and particularly to a network structure method for increasing the speed of the routing that determines what route is used to transmit communication information of packets with destination address added, and to a router for use in this method. In the Internet having a plurality of autonomous systems interconnected, fast routing can be made. The autonomous systems constituting the Internet or the like are divided into groups. The border routers of one group share routing information of the group, and the border routers of another group share routing information of the group. Each border router has a unit for separating a desired one from the autonomous systems of a corresponding group or consolidating an autonomous system of another group into the corresponding group, so that the amount of the routing information held can be adapted to the processing ability of the border routers within that group.