Method and device for establishing routing

The invention provides a communication network which comprises a first level node group and a second level node group, wherein the first level node group comprises a first node and a second node; the second level node group comprises a third node; the nodes in the first level node group and the second level node group respectively maintain the respective routing information of the node groups; and the covering regional scope of the second level node group is larger than the covering regional scope of the first level node group, the second level node group includes the first level node group, and the first node and the second node are included in the routing information of the first level node group and the second level node group. Through the layering communication system, most flow of a communication network for daily business operation can be limited within a small region, so the backbone network bandwidth which is not sufficient is prevented from being excessively occupied.