CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 8-1
Chapter 8
Advanced Routing Protocols
At a Glance
Instructor’s Manual Table of Contents
• Overview
• Objectives
• Teaching Tips
• Quick Quizzes
• Class Discussion Topics
• Additional Projects
• Additional Resources
• Key Terms
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 8-2
Lecture Notes
Overview
Routing protocols are an integral part of a functioning network. Distance-vector routing
protocols such as RIP version 1 or Interior Gateway Routing Protocol (IGRP) are sufficient
in simple networks; however, today’s complex networks demand more advanced protocols.
This chapter begins with a discussion of classful and classless routing protocols. It
continues with an examination of the classless routing protocols RIP version 2, EIGRP, and
OSPF. By the end of the chapter, you should be able to describe and configure each of these
protocols. The chapter concludes with a discussion of controlling routing traffic and basic
Border Gateway Protocol configuration.
Chapter Objectives
• Describe classful and classless routing protocols
• Describe and configure RIPv2
• Describe and configure EIGRP
• Describe and configure OSPF
• Control routing traffic
Teaching Tips
Classful and Classless Routing Protocols
1. Explain that classful routing protocols summarize networks to their major network
2. Mention that classful routing protocols cannot be used in networks with either
3. Examples of classful routing protocols include RIPv1 and IGRP.
Teaching
Tip
Routing protocols are divided into the broad categories of interior or exterior
gateway protocols and distance-vector protocols or link-state protocols. These
broad definitions describe where each routing protocol is best used, either within
the autonomous system or between autonomous systems. These definitions also
describe how the routing protocols handle routing table updates and routing table
creation.
4. Explain that classless routing protocols allow dynamic routing in discontiguous
networks. They carry subnet mask information in the routing table updates. Use Figures
5. Examples of classful routing protocols include RIPv2, EIGRP, OSPF, and BGP.
Teaching
Tip
In general, due to the complexity of modern networks and the use of VLSMs,
which require subnet mask information to be sent with update messages, most
networks use classless routing protocols.
Routing Information Protocol version 2
1. Define Routing Information Protocol version 2 (RIPv2) as a set of extensions to RIPv1.
2. Explain that the major change from RIPv1 to RIPv2 is RIPv2’s ability to carry subnet
mask information. RIPv2 multicasts its updates using the multicast address of 224.0.0.9.
3. Mention that RIPv2 provides a way to authenticate routing peers to provide enhanced
security to a network. Use Figures 8-11 through 8-15 to illustrate your explanation.
Teaching
Tip
Configuring RIPv2 is a simple process. Additionally, RIPv2 maintains backward
compatibility with RIPv1.
4. Explain that another enhancement of RIPv2 is its ability to authenticate routing peers.
Configuring RIPv2 authentication requires the following steps: (see Figures 8-16
through 8-18)
a. Define a key chain
b. Define keys in the key chain
Quick Quiz 1
1. ____ routing protocols summarize networks to their major network boundaries (Class
A, B, or C) and do not carry subnet mask information in their routing table updates.
2. In essence, the major improvement offered by a(n) ____ routing protocol is the ability
to carry subnet mask information in the routing table updates.
3. RIP authentication can occur either by passing the authentication keys in clear text or
via ____ authentication.
4. A(n) ____ is a number generated by MD5 from the secret key. This number cannot be
reverse-engineered easily enough for someone to guess the secret key.
Enhanced Interior Gateway Routing Protocol
1. Define Enhanced Interior Gateway Routing Protocol (EIGRP) as a Cisco proprietary
3. Mention that EIGRP uses nonperiodic, partial, and bounded routing table updates.
4. Explain that EIGRP makes use of a composite metric comprised of six different factors:
Hops, Load, Bandwidth, Reliability, Delay, and MTU. By default, the formula used for
5. Use Figures 8-19 and 8-20 to show an EIGRP example network.
Teaching
Tip
EIGRP is more than the addition of a few features to IGRP. In fact, while still
backward-compatible with IGRP, EIGRP is a significantly better routing
protocol for use in large enterprise networks.
EIGRP Components
2. Explain that neighbor discovery and maintenance allow EIGRP to discover neighbors
and keep track of their status. EIGRP must be able to keep updates bounded, sent only
3. Mention that because EIGRP is protocol-independent, it cannot use existing Transport
4. Explain that RTP can actually provide both reliable and unreliable delivery. Routing
table updates are an example of an EIGRP packet type that uses reliable multicast via
4. Explain that EIGRP supports optional authentication of routing peers. Configuring
EIGRP authentication requires the following steps:
a. Define a key chain
Open Shortest Path First
1. Define Open Shortest Path First (OSPF) as an open standards, link-state routing
2. Explain that link-state routing protocols allow routers to share a common view of the
3. Mention that one disadvantage of OSPF is that each router needs to hold a topological
database of the entire area.
5. Explain that OSPF is ideally suited for large networks because it can use a concept
OSPF Concepts
1. Describe the following OSPF concepts:
a. Link
b. Link-state
Teaching
Tip
EIGRP is a powerful routing protocol that greatly enhances Cisco-only networks.
However, because it is proprietary, many networks either will not or cannot use
it.
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 8-7
OSPF Operation
1. Use Figures 8-34 and 8-35 to describe the steps involved in OSPF, including:
a. An OSPF router forms adjacencies with neighbors
2. Explain that OSPF uses Dijkstra’s Shortest Path First Algorithm to find the best path.
Single-Area OSPF Configuration
2. Use Figures 8-36 and 8-37 to describe how to configure single-area OSPF.
OSPF Authentication
2. Explain that OSPF provides authentication of routing table updates via several methods,
including:
3. Mention to perform MD5 authentication of routing updates in OSPF, two steps must be
completed: (see Figures 8-38 through 8-41)
Controlling Route Traffic
1. Define the passive-interface command as an important entry-level command
2. Explain that the passive–interface command causes a router to listen only on the
Quick Quiz 2
1. ____ is a Cisco proprietary protocol designed to overcome the limitations found in
IGRP.
2. A(n) ____ in OSPF is a router’s interface.
3. OSPF uses a(n) ____ database, which holds the common view of the network formed
from the link-state advertisements that are received.
4. OSPF uses Dijkstra’s ____ algorithm to find the best path.
Class Discussion Topics
1. What are the main problems with classful routing protocols?
2. When should you use distance-vector and link-state routing protocols?
Additional Projects
1. Ask your students to read the following article at
2. Ask your students to write a report explaining how to set a preferred route by
influencing EIGRP metrics. Use the following link as a starting point:
ml.
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 8-9
Additional Resources
1. Routing Information Protocol
3. An Introduction to IGRP
4. Enhanced Interior Gateway Routing Protocol
5. Introduction to EIGRP
Key Terms
➢ adjacencies database The neighbor database in OSPF.
➢ adjacency Bidirectional communication formed by EIGRP neighbors.
/bandwidth of the link).
➢ designated router (DR) Used on broadcast, multiaccess OSPF networks as a central
point for adjacencies and LSAs.
➢ Diffusing Update Algorithm (DUAL) The algorithm used by EIGRP for path
selection.
➢ link-state The status of an interface on an OSPF router.
➢ MD5 Message Digest 5, an algorithm used to produce a secure hash of shared secret
passwords.
➢ Open Shortest Path First (OSPF) A classless link-state routing protocol that uses
areas to provide for hierarchical network design.