Cisco Systems CCNA 2 manual RIP routing process, Configuring RIP

7.2.1 RIP routing process

RIP is a distance-vector routing protocol that uses hop count as the metric for path selection. By default, the maximum hop count for RIP is 15 and routing updates are broadcast every 30 seconds. If RIP routes are received that would increase the metric to a number higher than 15 hops, the network is considered unreachable and the route is discarded. RIP also has other features that are used by distance vector routing protocols such as split horizon and hold- down mechanisms to prevent incorrect routing information from being propagated.

7.2.2 Configuring RIP

Basic RIP configuration consists of two steps:

1.Enable the routing protocol

2.Identify the directly connected networks, or the networks to advertise

The global configuration command router rip is used to enable RIP as the routing protocol. The network network address command allows the identification of directly-connected networks that will participate in the routing process. When the basic configuration of RIP is complete, regular updates are sent every 30 seconds and triggered updates are sent upon notification of metric changes.

The following is an example of RIP configuration:

BHM(config)#router rip – selects RIP as the routing protocol

BHM(config-router)#network 1.0.0.0 – specifies a directly connect network

BMH(config-router)#network 2.0.0.0 – specifies a directly connect network

Notice that the network statements configured under the RIP protocol are classful addresses. Students commonly configure the network command by using the IP address of the subnet. The IOS will change this to the classful network address.

The router interfaces associated with the directly connected networks will participate in the routing process. These interfaces will send and receive routing updates.

RIP can be further customized through the use of some optional configuration parameters:

•Apply offsets to routing metrics

•Adjust timers

•Specify a RIP version

•Enable RIP authentication

•Run IGRP and RIP concurrently

•Disable the validation of source IP addresses

•Enable or disable split horizon

82 - 238 CCNA 2: Routers and Routing Basics v3.1 Instructor Guide – Module 7 Copyright ♥ 2004, Cisco Systems, Inc.