RuggedCom RX1000, RX1100 manual Configuring Dynamic Routing, Quagga, RIP and Ospf, RIP Fundamentals

RuggedRouter™ User Guide

Chapter 13 – Configuring Dynamic Routing

Introduction

This chapter familiarizes the user with:

∙Enabling The Dynamic Routing Suite

∙Enabling And Starting OSPF and RIP

∙Configuring OSPF and RIP

∙Obtaining OSPF and RIP Status

∙OSPF and VRRP

Quagga, RIP and OSPF

Dynamic routing is provided by the Quagga suite of routing protocol daemons. Quagga provides three daemons for managing routing, the core, ripd and ospfd.

The core daemon handles interfacing with the kernel to maintain the router's routing table and to check link statuses. It tells RIP and OSPF what state links are in, what routes are in the routing table, and some information about the interfaces.

The ripd and ospfd daemon handles communications with other routers using the RIPv2 and OSPFv2 protocol, decides which routers preferred to forward to.

In complex legacy networks, both RIP and OSPF may be active on the same router at the same time. Usually, one on them is employed.

RIP Fundamentals

The Routing Information Protocol determines the best path for routing IP traffic over a TCP/IP network based on the number of hops between any two routers. It uses the shortest route available to a given network as the route to use for sending packets to that network.

The RuggedRouter RIP daemon (ripd) is an RFC1058 compliant implementation of RIP support RIP version 1 and 2. RIP version 1 is limited to obsolete class based networks, while RIP version 2 supports subnet masks as well as simple authentication for controlling which routers to accept route exchanges with.

RIP uses network and neighbor entries to control which routers it will exchange routes with. A network is either a subnet or a physical interface (it must to be a broadcast capable interface). Any router that is part of that subnet or connected to that interface may exchange routes. A neighbor is a specific router to exchange routes with specified by its IP address. For point to point links (T1/E1 links for example) one must use neighbor entries to add other routers to exchange routes with. The maximum number of hops between two points on a RIP network is 15, placing a limit on network size.

Link failures will eventually be noticed although it is not unusual for RIP to take many minutes for a dead route to disappear from the whole network. Large RIP networks could take over an hour to converge when link or route changes occur. For fast convergence and recovery, OSPF is a much better choice. RIP is a fairly old routing protocol and has mostly been superseded by OSPF.

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