This topic examines backbone networks [BNs] that are used to link LANs together and to link BNs to WANs. We begin with the various types of devices used in BNs and discuss several backbone architectures. We then turn to two technologies designed primarily for use in the BN [ATM and gigabit Ethernet]. The topic ends with a discussion of how to improve BN performance and of the future of BNs.
Objectives
■ Understand the internetworking devices used in BNs
■ Understand several common backbone architectures
■ Be familiar with gigabit Ethernet
■ Understand the best practice recommendations for backbone design
■ Be aware of ways to improve BN performance
Introduction
Most business organizations realize that information must be stored, retrieved, analyzed, acted on, and shared with others at a moment’s notice. Without an enterprise wide network or an Internet connection, moving information from one department LAN to another or to customers is difficult.
Interconnecting the organization’s diverse networks is critical. A backbone network (BN) is a high-speed network that connects many networks. BNs typically use higher-speed circuits to interconnect a series of LANs and provide connections to other
BNs, MANs, WANs, and the Internet. A backbone that connects many BNs spanning several nearby buildings for a single organization is often called a campus network. A BN also may be called an enterprise network if it connects all networks within a company, regardless of whether it crosses state, national, or international boundaries.
We begin this topic by describing several commonly used devices in the BN and then showing how those can be used to create different backbone architectures with different performance capabilities. Backbones used to be built with special technologies, but today most BNs use high-speed Ethernet.
