Compatible Systems 5.4 Manuale Utente

Pagina di 313
Appendices
285
AppleTalk Routing Example
Each AppleTalk physical network segment is assigned a network 
number/range by the routers on the segment. The network number (or range 
of numbers) can be between 1 and 65,279. In the diagram above, 100-200 is 
the network range for the backbone, and 1001 is the network number for the 
local net segment.
Non-extended and Extended AppleTalk Networks
The original AppleTalk specification, which is now referred to as AppleTalk 
Phase 1, used only a network number, not a network range. A network 
number was a sixteen bit value, which allowed numbers between 1 and 
65,534 to be used. The address of an individual device on the segment 
consisted of the network number, along with an 8 bit node address value. This 
scheme meant there could be a maximum of 254 devices per network 
segment. While this was more than adequate for LocalTalk networks, it was 
a major constraint on Ethernet networks.
AppleTalk Phase 2 introduced the concept of extended networks. While the 
node address remained an 8 bit number, network segments could now be 
identified by a range of network numbers between 1 and 65,279. Each 
number in the range allows 253 node addresses. These Phase 2 extended 
ranges should be used for all new AppleTalk installations.
“Seeding” a Network Segment
Establishing the network number/range for an AppleTalk network segment is 
referred to as “seeding” the network. You should generally only have one 
Backbone
Local
 Net
Router
Workstation
Workstation
Net: 100-200
Net: 1001