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1 © 2003, Cisco Systems, Inc. All rights reserved. CCNA 2 Module 9 Basic Router Troubleshooting
1 © 2003, Cisco Systems, Inc. All rights reserved.
CCNA 2 Module 9 Basic Router Troubleshooting
2 2 2 © 2003, Cisco Systems, Inc. All rights reserved.
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 Help link.
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To Locate Instructional Resource Materials on Academy Connection:
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• Go to the Tools section
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• Go to the Community link under Resources
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• Contact your parent academy!
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Objectives
• Examining the routing table
• Network testing
• Troubleshooting router issues
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The show ip route Command
The show ip route command displays the contents of the IP routing table.
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Static Routing
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Dynamic Routing
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Default Route
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Configuring a Default Route
• The ip default-network command establishes a default route in networks using dynamic routing protocols.
Router(config-router)#ip default-network network-number
• Creating an ip route to 0.0.0.0/0 is another way to configure a default route.
Router(config)#ip route 0.0.0.0 0.0.0.0 [next-hop-ip-address | exit-interface]
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Determining Route Source and Destination
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Determining L2 and L3 Addresses
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Determining Administrative Distance
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Determining the Route Metric
Routing protocols use metrics to
determine the best route to a destination.
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Determining the Route Next Hop
• Destination/next hop associations tell a router that a particular destination can be reached optimally by sending the packet to a particular router.
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Determining the Last Routing Update
• Use the following commands to find the last routing update:
show ip route
show ip route network
show ip protocols
show ip rip database
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Observing Multiple Paths to a Destination
• Some routing protocols support multiple paths to the same destination.
• Unlike single path algorithms, these multi-path algorithms permit traffic over multiple lines, provide better throughput, and are more reliable.
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Introduction to Network Testing
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Structured Approach to Troubleshooting
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• Broken cables
• Disconnected cables
• Cables connected to the wrong ports
• Intermittent cable connection
• Wrong cables used for the task at hand
• Transceiver problems
• DCE cable problems
• DTE cable problems
• Devices turned off
Typical Layer 1 Errors
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• Improperly configured serial interfaces
• Improperly configured Ethernet interfaces
• Improper encapsulation set
• Improper clock rate settings on serial interfaces
• Network interface card (NIC) problems
Typical Layer 2 Errors
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• Routing protocol not enabled
• Wrong routing protocol enabled
• Incorrect IP addresses
• Incorrect subnet masks
Typical Layer 3 Errors
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Layer 1 Problems in a Network
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Layer 3 Troubleshooting Using Ping
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Layer 7 Troubleshooting Using Telnet
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Troubleshooting Layer 1 Using show interfaces Command
The show interfaces serial command
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Troubleshooting Layer 2 Using show interfaces Command
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Troubleshooting Using show cdp neighbors Command
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Troubleshooting Using show cdp neighbors detail Command
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Troubleshooting Using traceroute Command
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Troubleshooting Routing Issues
The show ip route Command
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Troubleshooting Routing Issues
The show ip protocols Command
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Troubleshooting Using show controllers serial Command
The show controllers serial Command
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Introduction to debug
Debug syntax
