Information Technology Reference
In-Depth Information
ZIP maintains network number-to-zone name mappings in zone information tables (ZITs). ZITs are
stored in routers, which are the primary users of ZIP, but end nodes use ZIP during the startup process
to choose their zone and to acquire internetwork zone information. ZIP uses RTMP routing tables to keep
up with network topology changes. When ZIP finds a routing table entry that is not in the ZIT, it creates
a new ZIT entry. Figure 9-5 shows a sample ZIT.
Figure9-5
A Sample AppleTalk ZIT
Network
number
Zone
1
My
2
Your
3
Marketing
4
Documentation
5-5
Sales
AURP
AURP allows a network administrator to connect two or more AppleTalk internetworks through a foreign
network (such as Transmission Control Protocol/Internet Protocol [TCP/IP]) to form an AppleTalk
wide-area network (WAN). The connection is called a tunnel, which functions as a single, virtual data
link between the AppleTalk internetworks, as shown in Figure 9-6.
Figure9-6
An AppleTalk Tunnel
AppleTalk Internetwork A
AppleTalk Internetwork B
Router
Router
Foreign Network C
Router
AppleTalk Internetwork C
A router that connects an AppleTalk internetwork to a tunnel (that is, a router that runs AURP) is called
an
exterior router
. The exterior router sends AppleTalk data packets and routing information through the
foreign network by encapsulating the packets with the header information required by the foreign
