3Com corebuilder 3500 Implementation Manual page 451

A router uses these items to determine the best path along which to
forward a data packet to its destination. The routing table contains an
entry for each network that a router's datagram can reach within
15 hops. The table is aged at set intervals as follows:
1 After a specified period of time, the RTMP changes the status of an entry
from good to suspect.
2 After an additional period of time, the RTMP changes the status of an
entry from suspect to bad.
3 After an additional period of time, the RTMP changes the status of an
entry from bad to really bad.
4 The router removes the entry of a nonresponding router with a really bad
status.
The data in the routing table is cross-referenced to the Zone Information
Table (ZIT). This table maps networks into zones. See "Session Layer
Protocols" later in this chapter for more information about the ZIT.
Figure 80 illustrates a simple AppleTalk network, and Table 58 shows the
corresponding routing table.
Figure 80 A Simple AppleTalk Network
Network 5-5
Router 802
Interface 2
Router 24
Interface 1
Interface 3
Network 103-103
Network 64-64
Router 801
Router 36
Router 200
Network 12-12
Key Concepts 451
Network 18-20