There is a tendency to discount a network as just simple plumbing, to think that all you have to consider is the size and the length of the pipes or the speeds and feeds of the links, and to dismiss the rest as unimportant. Just as the plumbing in a large stadium or high rise has to be designed for scale, purpose, redundancy, protection from tampering or denial of operation, and the capacity to handle peak loads, a network requires similar consideration. As users depend on a network to access the majority of the information they need to do their jobs and to transport their voice or video with reliability, the network must be able to provide resilient, intelligent transport.
As a business grows, so does its networking requirements. Businesses rely on the network infrastructure to provide mission-critical services. Network outages can result in lost revenue and lost customers. Network designers must design and build an enterprise network that is scalable and highly available.
The campus local area network (LAN) is the network that supports devices people use within a location to connect to information. The campus LAN can be a single switch at a small remote site up to a large multi-building infrastructure, supporting classrooms, office space, and similar places where people use their devices. The campus design incorporates both wired and wireless connectivity for a complete network access solution.
This chapter discusses strategies that can be used to systematically design a highly functional network, such as the hierarchical network design model and appropriate device selections. The goals of network design are to limit the number of devices impacted by the failure of a single network device, provide a plan and path for growth, and create a reliable network.