HP 200 Series Services And Applications page 160

AppleTalk Phase 2 Routing Service
Half router: Two routers, each connected to one or more AppleTalk
LANs, and connected to each other through long-distance communi-
cation links, are called half routers.
Figure 2. Half Router Configuration
Backbone router: Routers, each connected to one or more AppleTalk
LANs, connected together through either an Ethernet backbone or
an X.25 packet-switching backbone network, are called backbone
routers. Backbone networks do not have any AppleTalk end nodes
attached.
Figure 3. Backbone Router Configuration
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