Chapter 2. VLAN Operations
This chapter explores probably the most fundamental concept of modern LAN switching: virtual LANs (VLANs). In legacy Ethernet networks of the 1980s and early 1990s, the concept of virtual LANs did not exist; instead, only the concept of physical LANs existed. Layer 1 and Layer 2 Ethernet devices such as hubs and bridges were dedicated to a single, physical LAN, and implementing another LAN required more hubs and bridges. Today, LAN switches have the capability to provide connectivity for multiple physical LANs by implementing the concept of virtual LANs. In this chapter you learn about transparent bridging, which is the function provided by a bridge on a single physical LAN. This concept is then extended to VLANs, and you learn how they work and how to configure them.
After some initial introductory material, this chapter presents the following configuration scenarios, which provide you with the practical knowledge required to implement spanning tree, which provide you with the practical knowledge required to implement VLANs: