The LSP 70 may include other information fields as defined by the routing protocol being implemented e.g. IS-IS, but these are not shown in FIG. 2b for reasons of clarity. [0053] Conveniently, the LSP 70 can be generated in accordance with a protocol entitled ???Use of OSI IS-IS for Routing in TCP/IP and Dual environments??? (commonly known as Integrated IS-IS) which is detailed in Request for Com