Patent ID: 8223666

Claim:
A method of constructing a forwarding database for a data communications network comprising a plurality of network components and supporting at least first and second topologies having one or more common network components, wherein the forwarding database includes a plurality of entries providing forwarding information for data destined for a related network component, the method comprising the steps, performed at a constructing network component, of: deriving topology dependent forwarding information for data destined for a network component; and including the topology dependent forwarding information at a related forwarding database entry; wherein the topology dependent forwarding information is associated with both forwarding instructions for the first topology and forwarding instructions for the second topology; wherein the forwarding database comprises a single prefix tree and the forwarding database entry comprises a prefix entry; in which the topology dependent forwarding information is derived by inheriting the forwarding information from a covering entry in further comprising the step of identifying a forwarding database entry for the related network component for which data is destined, classifying the data to identify its topology, and selecting the topology dependent forwarding information accordingly.