ROUTING METHOD AND APPARATUS FOR OPTIMISING AUTO-TUNNELLING IN A HETEROGENEOUS NETWORK

In the preferred embodiment, the invention provides a modified Shortest Path First routing algorithm for use in a heterogeneous network. The routing algorithm is modified to include predetermined heterogeneous characteristics of the netwo rk nodes and to take these characteristics into account when calculating the shortest paths. For example, information may be included in the algorithm which identifies heterogeneous network nodes as it oaloulates shortest paths. Once a node has been identifi ed as heterogeneous, i.e., capable of supporting at least two protocol sets, this information is carried over into subsequent path entries created by the routing algorithm. The algorithm then uses the encapsulation capability identifier in the calculati on of the shortest paths by including the cost of auto-tunnelling between heterogeneou s nodes to be taken into account when determining the short path.