SUMMARY
LocalTalk networks are different from PC networks and require you to
consider special concepts and issues when setting them up. Most
LocalTalk networks are internets--separate physical networks connected
by routers that enable network communications by maintaining a map
of the physical network on the internet and forwarding data to the
correct network destinations.
Seed routers provide other specialized internet functions. For more
information on them see
105155.
ROUTING TABLE MAINTENANCE PROTOCOL (RTMP)
AppleTalk uses routing table maintenance protocol (RTMP) to maintain
information about internetworking addresses and connections. Routers
provide interfaces for RTMP and numerous other protocols and
processes.
The routing table contains all possible destination network numbers
(or the network range) and five entries necessary for forwarding
datagrams:
- the number of the data link port that connects to the local
network's DDP
- the destination network number
- the next router's node ID
- the number of hops needed to reach the destination network
- a cross-reference into the zone information table
The routers use RTMP to exchange this routing information, keeping
their tables current and minimizing internetwork delays.
ZONE INFORMATION PROTOCOL (ZIP)
The zone information protocol (ZIP) maintains a zone information table
that the name binding protocol (NBP) uses to match networks with their
zones. ZIP also helps routers maintain their tables.
EXAMPLE
If you send a job across a router to a printer. A sniff of the request
will show you the process stages:
The process for a file request is very similar, although it uses the
file access protocol (FAP) instead of the printer access protocol
(PAP). If you are looking for network or broadcast problems, use the
ZIP and RTMP packets to verify that the information (number of hops
and network ranges) is correct.