1 © 2003, Cisco Systems, Inc. All rights reserved. CCNA 2 v3.0 Module 9 Basic Router Troubleshooting

222 © 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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444 © 2003, Cisco Systems, Inc. All rights reserved. Objectives Examining the routing table Network testing Troubleshooting router issues

555 © 2003, Cisco Systems, Inc. All rights reserved. Examining the routing table

666 © 2003, Cisco Systems, Inc. All rights reserved. The show ip route Command The show ip route command displays the contents of the IP routing table.

777 © 2003, Cisco Systems, Inc. All rights reserved. Static Routing

888 © 2003, Cisco Systems, Inc. All rights reserved. Dynamic Routing

999 © 2003, Cisco Systems, Inc. All rights reserved. Default Route

10 © 2003, Cisco Systems, Inc. All rights reserved. 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 is another way to configure a default route. Router(config)#ip route [next-hop-ip-address | exit-interface]

11 © 2003, Cisco Systems, Inc. All rights reserved. Determining Route Source and Destination

12 © 2003, Cisco Systems, Inc. All rights reserved. Determining L2 and L3 Addresses

13 © 2003, Cisco Systems, Inc. All rights reserved. Determining Administrative Distance

14 © 2003, Cisco Systems, Inc. All rights reserved. Determining the Route Metric Routing protocols use metrics to determine the best route to a destination.

15 © 2003, Cisco Systems, Inc. All rights reserved. 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.

16 © 2003, Cisco Systems, Inc. All rights reserved. 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

17 © 2003, Cisco Systems, Inc. All rights reserved. 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.

18 © 2003, Cisco Systems, Inc. All rights reserved. Network testing

19 © 2003, Cisco Systems, Inc. All rights reserved. Introduction to Network Testing

20 © 2003, Cisco Systems, Inc. All rights reserved. Structured Approach to Troubleshooting

21 © 2003, Cisco Systems, Inc. All rights reserved. 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

22 © 2003, Cisco Systems, Inc. All rights reserved. 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

23 © 2003, Cisco Systems, Inc. All rights reserved. Routing protocol not enabled Wrong routing protocol enabled Incorrect IP addresses Incorrect subnet masks Typical Layer 3 Errors

24 © 2003, Cisco Systems, Inc. All rights reserved. Layer 1 Problems in a Network

25 © 2003, Cisco Systems, Inc. All rights reserved. Layer 3 Troubleshooting Using Ping

26 © 2003, Cisco Systems, Inc. All rights reserved. Layer 7 Troubleshooting Using Telnet

27 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting router issues

28 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting Layer 1 Using show interfaces Command The show interfaces serial command

29 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting Layer 2 Using show interfaces Command

30 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting Using show cdp neighbors Command

31 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting Using show cdp neighbors detail Command

32 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting Using traceroute Command

33 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting Routing Issues The show ip route Command

34 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting Routing Issues The show ip protocols Command

35 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting Using show controllers serial Command The show controllers serial Command

36 © 2003, Cisco Systems, Inc. All rights reserved. Introduction to debug Debug syntax