Sub-route networks consist of a more or less large number of arbitrarily structured and interconnected node computers. The messages transmitted between the data terminal equipment (DTE), the data source and data sink, are transmitted indirectly, from node to node. This network configuration is used in wide area networks (WAN) and uses data packet switching.
In partial link operation, a message or message parts are transported sequentially over several partial links using the store-and-forward method. Since the distances between the end points can usually be very large and many nodes are interposed, routing and the use of network resources play a decisive role. To determine the optimal route, a classification of routing methods is useful.