Ccna3 ospf

www.ciscopress.comCopyright 2003

CCNA 3 Chapter 3

Single-Area OSPF

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Objectives

• Link-state routing protocol

• Single-area OSPF concepts

• Single-area OSPF configuration


Overview of Link-State and Distance Vector Routing


Link-State Routing Features

• Respond quickly to network changes

• Send triggered updates only when a network change has occurred

• Send periodic updates known as link-state refreshes

• Use a hello mechanism to determine the reachability of neighbors


How Routing Information Is Maintained


Link-State Routing Algorithms


Advantages and Disadvantages of Link-State Routing


Comparing Distance Vector and Link-State Routing


Single-Area OSPF Concepts


OSPF Overview

OSPF is becoming the preferred IGP protocol when compared with RIPv1 and RIPv2 because it is scalable.


OSPF Terminology


Comparing OSPF with Distance Vector Routing Protocols


Shortest Path Algorithm

The best path is the lowest-cost path.


OSPF Network Types


OSPF Hello Protocol


Steps in the Operation of OSPF


Single-Area OSPF Configuration


Configuring the OSPF Routing Process


Configuring OSPF Loopback Address and Router Priority


Configuring Router Priority

The priorities can be set to any value from 0 to 255. A value of 0 prevents that router from being elected. A router with the highest OSPF priority will win the election for DR.


Modifying OSPF Cost Metric


Configuring OSPF Authentication


Configuring OSPF Timers


OSPF, Propagating a Default Route


Common OSPF Configuration Issues


Verifying OSPF Configuration

• show ip protocol• show ip route• show ip ospf interface• shop ip ospf• show ip ospf neighbor detail• show ip ospf database


The debug and clear Commands for OSPF Verification

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Ccna3 ospf