System information

CHAPTER
Troubleshooting AppleTalk 9-175
9
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 OSI reference model layers to which
they map.