The All-New Switch Book: The Complete Guide to LAN Switching Technology, Second Edition

1.5. Terminology

Q: Does a station send frames or packets onto a network?

Q: Is a device that interconnects Ethernets to an FDDI backbone called a bridge or a router?

Q: Should you care?

A: Yes, yes, and yes.

Writers (especially in the lay or trade press) often get free and loose with terminology. Packets and frames are treated interchangeably; routers are called bridges, bridges are called gateways, or multilayer switches are called switches even though they do not fit the traditional definition of a switch. (Multilayer switches will be discussed in further detail in Chapter 4.) In many cases, it really does not matter whether the wording reflects strict technical correctness. Such details are usually not vital for a broad, high-level understanding of system behavior. We, however, have no such luxury here. This book examines the behavior of stations in internetworking devices at a highly detailed level. As such, we often need to be precise in our terminology, so that it is clear exactly what is being discussed or manipulated.

Network terminology tends to follow the layered architectural model. We use different terms to describe the devices, objects, and processes that implement the functions of each layer. This actually makes life somewhat easier; we can generally tell which architectural layer is being discussed just from the terms being used.

1.5.1. Applications, Clients, and Service Providers

As depicted in Figure 1-16, each layer in a suite of protocols can be seen to use ...