Addressing, bridging, and source routing (LAN interconnection)

The concept of source routing for the interconnection of local networks is described. An architectural framework is provided to emphasize the principal advantages inherent with such a bridging mechanism. Motivation for this form of routing is shown to be a consequence of the address structure within the local network standards that have been adopted by IEEE, the European Computer Manufacturers Association (ECMA), and the International Organization for Standardization (ISO). As with many internetworking protocols, the use of a qualified address structure allows a more efficient routing mechanism. The physical address of a station, although not explicitly present in each transmitted frame, is implied by its attachment to a specific segment of the local network. This subtle point relative to local network addressing provides the foundation for the incorporation of source routing protocols.<>