1. A routing system in a multimedia integrated network having nodes connected by links, the multimedia integrated network providing at least one type of communication in a packet transmitted via the links between the nodes of the multimedia integrated network, where the at least one type of communication requires at least one condition, said routing system comprising in each node: a neural network of an interconnection type, formed of neurons, for determining a packet output direction of each packet from the node, said neurons comprising node correspondence neurons corresponding to the nodes forming the multimedia integrated network and link correspondence neurons corresponding to the links connecting the nodes; and an external stimulus input unit, operatively connected to said neural network, for outputting an external stimulus to each neuron forming said neural network in accordance with a present state of the multimedia integrated network and the condition required by the communication provided by the multimedia integrated network, to enable the neural network in each node to determine the packet output direction in accordance with the present state of the multimedia integrated network and the condition required by the communication.