Protocol Analysis for Triggered RIP (RFC2092)
Original Publication Date: 1997-Jan-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
S. Sherry: AUTHOR [+2]
As required by Routing Protocol Criteria , this report documents the key features of Triggered Extensions to RIP to Support Demand Circuits  and the current implementation experience.
Network Working Group S. Sherry
Request for Comments: 2092 Xyplex
Category: Informational G. Meyer
Protocol Analysis for Triggered RIP
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
As required by Routing Protocol Criteria , this report documents
the key features of Triggered Extensions to RIP to Support Demand
Circuits  and the current implementation experience.
As a result of the improved characteristics of Triggered RIP, it is
proposed that Demand RIP  be obsoleted.
The authors wish to thank Johanna Kruger and Jim Pearl of Xyplex for
many comments and suggestions which improved this effort.
1. Protocol Documents
"Triggered Extensions to RIP to Support Demand Circuits"  suggests
an enhancement to the "Routing Internet Protocol" (RIP)  and
"RIP-2"  to allow them to run more cost-effectively on Wide Area
Triggered RIP requires that there is an underlying mechanism for
determining unreachability in a finite predictable period.
The triggered extensions to RIP are particularly appropriate for WANs
where the cost - either financial or packet overhead - would make
periodic transmission of routing (or service advertising) updates
o Connection oriented Public Data Networks - for example X.25 packet
switched networks or ISDN.
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
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