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1© 2003, Cisco Systems, Inc. All rights reserved.
CCNA 2 v3.0 Module 7
Distance Vector Routing
Protocols

Purpose of This PowerPoint
• This PowerPoint primarily consists of the Target
Indicators (TIs) of this module in CCNA version
3.0.
• It was created to give instructors a PowerPoint to
take and modify as their own.
• This PowerPoint is:
NOT a study guide for the module final assessment.
NOT a study guide for the CCNA certification exam.
• Please report any mistakes you find in this
PowerPoint by using the Academy Connection
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Objectives
• Distance vector routing
• RIP
• IGRP

Distance Vector Updates

Problem: Routing Loops
• Routing loops can occur when
inconsistent routing tables are not
updated due to slow convergence in a
changing network.

Problem: Counting to Infinity

Solution: Defining a Maximum for
Infinity

Solution: Split Horizon

Solution: Route Poisoning

Solution: Triggered Updates

Solution: Holddown Timers

Key Characteristics of RIP

RIP Commands
• Using router rip and network
commands to Enable RIP
• Enabling RIP on an IP-addressed network
• Monitoring IP packet flow using the show
ip protocol command
• The show ip route command

Configuring RIP

Using the ip classless Command

RIP Configuration Issues
• To reduce routing loops and counting to
infinity, RIP uses the following:
Defining infinity
Split horizon
Route poisoning & poison reverse
Triggered updates
Holddown timers

The show ip protocols Command

The show ip route Command

Troubleshooting RIP Update Issues
• debug ip rip
• show ip rip database
• show ip protocols {summary}
• show ip route
• debug ip rip {events}
• show ip interface brief

Preventing Routing Updates through
an Interface

Load Balancing with RIP

Administrative Distance

Integrating Static Route with RIP
• A router running RIP can receive a default
route via an update from another router
running RIP.
• Another option is for the router to
generate the default route itself.
• The administrator can override a static
route with dynamic routing information by
adjusting the administrative distance
values.

IGRP Features

IGRP Commands
• Using router igrp and network
commands to enable IGRP
• Enabling IGRP on an IP-addressed
network
• Monitoring IP packet flow using the show
ip protocol command
• The show ip interfaces command
• The show ip route command
• The debug ip rip command

IGRP Metrics
• Bandwidth – The lowest bandwidth value
in the path
• Delay – The cumulative interface delay
along the path
• Reliability – The reliability on the link
towards the destination as determined by
the exchange of keepalives
• Load – The load on a link towards the
destination based on bits per second

IGRP Routes:
Interior, System, & Exterior

IGRP Stability Features
• Holddowns, Split horizons, & Poison-reverse
updates

Configuring IGRP

Migrating RIP to IGRP
1. Verify existing routing protocol (RIP) on
the routers to be converted.
2. Configure IGRP on RouterA and RouterB
3. Enter show ip protocols on RouterA
and RouterB
4. Enter show ip route on RouterA and
RouterB

Verifying IGRP Configuration
• Some commands for checking IGRP
configuration are as follows:
show interface interface
show running-config
show running-config interface
interface
show running-config | begin interface
interface
show running-config | begin igrp
show ip protocols

Troubleshooting IGRP
• The following commands are useful when
troubleshooting IGRP:
show ip protocols {summary}
show ip route
debug ip igrp events IGRP protocol
events
debug ip igrp transactions IGRP
protocol transactions
ping
traceroute

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