Protocol Analysis for Triggered RIP (RFC2092)
Original Publication Date: 1997-Jan-01
Included in the Prior Art Database: 2019-Feb-16
Internet Society Requests For Comment (RFCs)
S. Sherry: AUTHOR [+1]
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. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.
Network Working Group S. Sherry Request for Comments: 2092 Xyplex Category: Informational G. Meyer Shiva January 1997
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 Networks (WANs).
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 unacceptable:
o Connection oriented Public Data Networks - for example X.25 packet switched networks or ISDN.
Sherry & Meyer Informational [Page 1]
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...