8-6 CHAPTER 8: ROUTING WITH APPLETALK TECHNOLOGY
An AppleTalk intranet has four transport layer protocols:
■ Routing Table Maintenance Protocol (RTMP)
■ AppleTalk Echo Protocol (AEP)
■ AppleTalk Transaction Protocol (ATP)
■ Name Binding Protocol (NBP)
Routing Table Maintenance Protocol (RTMP)
This protocol maintains information about AppleTalk addresses and
connections between different networks. It specifies that each router:
■ Learns new routes from other routers
■ Deletes a route if the local router has not broadcast the route to the
network for a certain period of time
Each router builds a routing table for dynamic routing operations in an
AppleTalk intranet. Every 10 seconds, each router sends an RTMP data
packet to the network. Routers use the information that they receive in
the RTMP broadcasts to build their routing tables. Each entry in the
routing table contains these items:
■ The network range
■ The distance in hops to the destination network
■ The interface number of the destination network
■ The state of each port (good, suspect, bad, or really bad)
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.
To Next Page
Loading...
