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Chapter 4: Networks
where to send each packet of data. Each physical network must have one or more seed
routers that broadcast the routing information for that network.
Not all routers must be seed routers. Routers that are not seed routers maintain a map of
the physical networks on the internet and forward data to the correct physical network.
Seed routers perform these functions too, but they also initialize the routing information,
such as network numbers and zone lists, for one or more physical networks
Phase 1 vs. Phase 2 Networks
There are two types of AppleTalk networks: Phase 1 and Phase 2.
AppleTalk Phase 1 was the original AppleTalk protocol architecture designed to support
networking for small workgroups. Phase 1 could only support a single physical network
that had just one network number and one zone.
AppleTalk Phase 2 enhances the routing and naming services of AppleTalk. This means
improved network traffic and better router selection. You can now create AppleTalk
networks that support more than 254 nodes and have multiple zones. You must use Phase
2 to run Services for Macintosh.
Routing Information
AppleTalk routing information includes:
•
A network number or network range associated with each physical network
•
The zone name or zone list associated with each physical network
•
The default zone for the network (if the network has multiple zones)
The network number or network range is the address or range of addresses assigned to
the network. A network number is unique and identifies a particular AppleTalk physical
network. By keeping track of network numbers and network ranges, routers can send
incoming data to the correct physical network. A network number can be any number
from 1 through 65,279.
LocalTalk networks can have only a single network number; EtherTalk, TokenTalk and FDDI
networks can have network ranges.
A zone is a logical grouping that simplifies browsing the network for resources, such as
servers and printers. It is similar to a domain in Windows NT Server networking, as far as
browsing is concerned. In LocalTalk networks, each physical network can be associated
with only one zone. However, for EtherTalk, TokenTalk, or FDDI, you have more flexibility
in assigning zones. Each EtherTalk, TokenTalk, or FDDI network can have one or more
zones associated with it, and each zone can include servers and printers on one or more
physical networks. This allows you to group servers and printers logically into zones so
that users can easily locate and access the servers and printers, no matter what physical
networks they are on.
Each Macintosh client on the network is assigned to a single zone. However, each client
can access servers and printers in any zone on the network. Zones make accessing
network resources simpler for users. When users use the Chooser to view the network,
they see only the resources in a single zone at a time, preventing them from having to
navigate through huge numbers of resources on large networks to find the resources that
they need. You can put the clients, servers, and printers used by a single group into a
single zone so that users will see only the resources they typically use but will still be able
to access resources in other zones when required.
A zone list includes all the zones associated with that network. One of these zones is the
network's default zone, to which the Macintosh clients on that network are assigned by
default. Users can configure the client to be in a different zone, however.
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