Before getting into the protocols of the AppleTalk suite, we should first take a look at the concept of AppleTalk networks and zones. Two varieties of AppleTalk networks exist – these are known as extended and nonextended, and are described below.
Nonextended AppleTalk Network. In AppleTalk phase 1, only nonextended networks existed. These are normally not used any more, mainly because they limit the network to a single physical segment. All nonextended networks are also limited to a single network number and a single AppleTalk zone.
Extended AppleTalk Network. Available in AppleTalk Phase 2, an extended network allows multiple network numbers to exist, along with multiple AppleTalk zones. Because a given network number can only support a maximum of 253 nodes, it is also possible to configure multiple network numbers for a single physical segment on an extended network. This is referred to as a cable range. Almost all AppleTalk deployments today are based on extended networks.
But what is an AppleTalk zone? An AppleTalk zone is a logical grouping (or administrative unit) of AppleTalk resources, somewhat similar to a workgroup on a Microsoft network. With any Data Link protocol other than LocalTalk, zones can span multiple networks, or there can be multiple zones on a single network. On a LocalTalk network, only one zone can exist. Zones are commonly created according to functional areas or departments – for example, you might have a Finance zone or an IT zone. On a Macintosh computer, users can browse zone resources using the Chooser application.