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Protocol Analysis for Extensions to RIP to Support Demand Circuits (RFC1581)

IP.com Disclosure Number: IPCOM000002415D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 4 page(s) / 7K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

G. Meyer: AUTHOR

Abstract

As required by Routing Protocol Criteria [1], this report documents the key features of Routing over Demand Circuits on Wide Area Networks - RIP [2] and the current implementation experience.

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Network Working Group G. Meyer

Request for Comments: 1581 Spider Systems

Category: Informational February 1994

Protocol Analysis for Extensions to RIP to Support Demand Circuits

Status of this Memo

This document provides information for the Internet community. This

document does not specify an Internet standard of any kind.

Distribution of this document is unlimited.

Abstract

As required by Routing Protocol Criteria [1], this report documents

the key features of Routing over Demand Circuits on Wide Area

Networks - RIP [2] and the current implementation experience.

Acknowledgements

I would like to thank colleagues at Spider, in particular Richard

Edmonstone and Alan Turland who developed Spider's IP RIP and IPX RIP

and SAP implementations.

1. Protocol Documents

"Extensions to RIP to Support Demand Circuits" [2] suggests an

enhancement to the "Routing Internet Protocol" (RIP) [3] and "RIP-2"

[4] to allow them to run more cost-effectively on Wide Area Networks

(WANs). Network management extensions for Demand RIP are described

in RIP Version 2 MIB Extensions [5].

2. Applicability

Demand RIP requires that there is an underlying mechanism for

determining unreachability in a finite predictable period.

The demand 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.

o Point-to-point links supporting PPP link quality monitoring or

echo request to determine link failure.

A demand 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 or fixed point-to-point links; 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. 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 and fragment number

information. An acknowledgement packet is also defined.

3.2 Circuit Manager

The circuit manager running below the...