RFC 2092 (rfc2092) - Page 2 of 6
Protocol Analysis for Triggered RIP
Alternative Format: Original Text Document
RFC 2092 Triggered RIP Protocol Analysis January 1997
o Point-to-point links supporting PPP link quality monitoring or
echo request to determine link failure.
A triggered RIP implementation runs standard RIP on Local Area
Networks (LANs) allowing them to interoperate transparently with
implementations adhering to the original specifications.
3. Key Features
The proposal shares the same basic algorithms as RIP or RIP-2 when
running on LANs; Packet formats, broadcast frequency, triggered
update operation and database timeouts are all unmodified.
The new features operate on WANs which use switched circuits on
demand to achieve intermittent connectivity; Or on permanent WAN
connections where there is a desire to keep routing packet overhead
to a minimum. Instead of using periodic 'broadcasts', information is
only sent as triggered updates. The proposal makes use of features
of the underlying connection oriented service to provide feedback on
connectivity.
3.1 Triggered Updates
Updates are only sent on the WAN when an event changes the routing
database. Each update is retransmitted until acknowledged.
Information received in an update is not timed out.
The packet format of a RIP response is modified (with a different
unique command field) to include sequence number information. An
acknowledgement packet is also defined.
3.2 Circuit Manager
The circuit manager running below the IP network layer is responsible
for establishing a circuit to the next hop router whenever there is
data (or a routing update) to transfer. After a period of inactivity
the circuit will be closed by the circuit manager.
If the circuit manager fails to make a connection a circuit down
indication is sent to the routing application. The circuit manager
will then attempt at (increasing) intervals to establish a
connection. When successful a circuit up indication is sent to the
routing application.
Sherry & Meyer Informational