An application of knowledge-based system design concepts to the design of local area networks (LANs) is illustrated. A system entity structure representation of a LAN is developed. This representation unifies a variety of possibilities for LAN design architecture. In a design session, the LAN design domain is subsequently restricted by pruning the entity structure with respect to network design objectives. A LAN model is then synthesized using a production rule scheme. The benefit of the knowledge-based LAN design is discussed.