Introduction

So far this book has examined topologies, media access methods, networking standards, and cable types and connectors. To complete our examination of networking on a physical level, this chapter looks at the network devices used to create networks. Objective: 1.6  Identify the purpose, features, and functions of the following network components: ►  Hubs ►  Switches ►  Bridges ►  Routers ►  Gateways ►  CSU/DSU ►  Wireless access points (WAPs) ►  Modems ►  Network interface cards (NICs) ►  ISDN adapters ►  Transceivers ►  Firewalls Each of these devices fulfills a specific role in a network; however, only the largest and most complex environments use all of them. We’ll begin our discussion of networking devices with perhaps the most simple and common network device used today: the hub. NOTE Repeaters Traditionally, any discussion of networking components would include repeaters, but today repeaters are a little outdated. Repeaters were once used to increase the usable length of the cable, and they were most commonly associated with coaxial network configurations. Because coaxial networks have now fallen out of favor, and because the functionality of repeaters has been built in to other devices, such as hubs and switches, repeaters are rarely used. For this reason, CompTIA has elected to leave them out of the required knowledge for the Network+ exam. Hubs Hubs are simple network devices, and their simplicity is reflected in their low cost. Small hubs with four or five ports (often referred to as workgroup hubs) cost less than $50; with the requi­site cables, they provide everything needed to create a small network. Hubs with more ports are available for networks that require greater capacity. Figure 3.1 shows an example of a work­group hub, and Figure 3.2 shows an example of the type of hub you might see on a corporate network. FIGURE 3.1 A workgroup hub. FIGURE 3.2 A high-capacity, or high- density, hub.