Overview
Designing a network can be a challenging task that involves more than just connecting computers together. A network requires many features in order to be reliable, manageable, and scalable. To design reliable, manageable, and scalable networks, a network designer must realize that each of the major components of a network has distinct design requirements.

Network design is becoming more difficult despite improvements in equipment performance and media capabilities. Using multiple media types and interconnecting LANs with other external networks makes the networking environment complex. Good network design will improve performance and also reduce the difficulties associated with network growth and evolution.

A LAN spans a single room, a building, or a set of buildings that are close together. A group of buildings that are on a site and belong to a single organization are referred to as a campus. The design of larger LANs includes identifying the following:

  • An access layer that connects end users into the LAN
  • A distribution layer that provides policy-based connectivity between end-user LANs
  • A core layer that provides the fastest connection between the distribution points

Each of these LAN design layers requires switches that are best suited for specific tasks. The features, functions, and technical specifications for each switch vary depending on the LAN design layer for which the switch is intended. Understanding the role of each layer and then choosing the switches best suited for that layer ensures the best network performance for LAN users.

Students completing this module should be able to:

  • Describe the four major goals of LAN design
  • List the key considerations in LAN design
  • Understand the steps in systematic LAN design
  • Understand the design issues associated with the Layer 1, 2, and 3 LAN structure, or topology
  • Describe the three-layer design model
  • Identify the functions of each layer of the three-layer model
  • List Cisco access layer switches and their features
  • List Cisco distribution layer switches and their features
  • List Cisco core layer switches and their features