Abstract: The object of the invention is to perform an automatic decomposition of a packet switching network in backbone nodes and subareas nodes to speed up the routing path search without degrading the optimization criterion of the routing algorithm and without generating additional control messages on the network.Currently, routing algorithms compute all the available paths in the network, from the source node to the destination node before to select an optimal route. However, networks are rarely fully meshed. They are usually built around a hierarchical structure: a set of nodes, interconnected by high throughput lines, are used to build a backbone with a high degree of meshing and then, local nodes are grouped in geographical subareas themselves attached to the backbone. Routing algorithms can take advantage of this particular network topology to drastically reduce the complexity of paths computation.