• The set of all communicating computers within a campus/university is said to be part of a Campus Area Network (CAN).
•  A CAN is actually a collection of inter-connected LAN networks within a limited geographical area, spans across multiple buildings and is usually owned by a single administrative body.

A typical CAN layout is given below:

• Each building in the campus would usually have one or more LANs, with each LAN having a set of computers connected together by a L2 switch.
• A backbone network device in the form of a more powerful L2 switch interconnects the LANs of different buildings. For external communication to the internet, the backbone L2 switch connects to a L3 Router (usually called the external gateway).
• A small Enterprise / Corporate network is similar to a CAN