Packet Guide to Core Network Protocols

Chapter 5. Network Equipment

Every network needs a certain amount of equipment facilitating the transmission of data. Equipment selection is based on the task at hand. To select the best possible device, we have to understand operations and ask questions regarding the interconnection of networks and computers. In addition to handling a specific set of tasks, infrastructure devices are designed to operate at a particular layer of the TCP/IP model. This means that hubs (also called repeaters), switches (or bridges), routers, access points (APs), and gateways can be inserted into the model just like protocols. While contemporary networks continue to use devices that are clearly defined, newer equipment can cross layer boundaries.

This chapter examines the components of a typical network in terms of their operation and behavior. We will also take a look at some of the security concerns associated with each. This includes changes for contemporary equipment, small office home office (SOHO) networks and the ubiquitous home gateway.

Figure 5-1 provides the basis for most of this chapter. Both the OSI and TCP/IP models are represented along with the major protocols at each layer. The hubs, switches, and the router interconnect the two sides. The solid line at the bottom represents the physical connection between the devices, or what we might call the transmission path. However, devices may make decisions at upper layers, so they are logically connected via the dotted line. For example, switches ...