Information Technology Reference
In-Depth Information
9
CHAPTER
Troubleshooting AppleTalk
In the early 1980s, as Apple Computer, Inc., was preparing to introduce the Macintosh computer, Apple
engineers knew that networks would become a critical need. They wanted to ensure that a
Macintosh-based network was a seamless extension of the revolutionary Macintosh user interface. With
these two goals in mind, Apple decided to build a network interface into every Macintosh and to integrate
that interface into the desktop environment. Apple's new network architecture was called AppleTalk.
Although AppleTalk is a proprietary network, Apple has published AppleTalk specifications in an
attempt to encourage third-party development. Today, many companies—including Novell, Inc., and
Microsoft Corporation—are successfully marketing AppleTalk-based products.
The original implementation of AppleTalk, which was designed for local workgroups, is now commonly
referred to as AppleTalk Phase 1. With the installation of more than 1.5 million Macintosh computers in
the first five years of the product's life, however, Apple found that some large corporations were
exceeding the built-in limits of AppleTalk Phase 1, so they enhanced the protocol. The enhanced
protocol, known as AppleTalk Phase 2, improved the routing capabilities of AppleTalk and allowed
AppleTalk to run successfully in larger networks.
AppleTalk Technology Basics
AppleTalk was designed as a client/server distributed network system. In other words, users share
network resources (such as files and printers) with other users. Computers supplying these network
resources are called
servers
; computers using a server's network resources are called
clients
. Interaction
with servers is essentially transparent to the user because the computer itself determines the location of
the requested material and accesses it without further information from the user. In addition to their ease
of use, distributed systems also enjoy an economic advantage over peer-to-peer systems because
important materials can be located in a few, rather than many, locations.
In Figure 9-1, AppleTalk protocols are shown adjacent to the Open System Interconnection (OSI)
reference model layers to which they map.
