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Applying Cisco Troubleshooting Tools

Chapter Description

This sample chapter from CCNP Support Exam Certification Guide introduces some powerful troubleshooting tools that are built into the Cisco IOS. As with other tools, it is important that you identify when to use them and what information they reveal. Because some of these tools have an impact on the way routers operate and may impede the routers' utmost performance, it is essential to use them with care. To better understand the output of these commands, and to recognize what router internal operations they affect, this chapter discusses router internal components and operations. As each tool/command is introduced, its usefulness is described and tips are given on how to use it effectively.

show version Command

This command is one of the most popular fact-gathering commands. Example 4-6 displays a sample of the show version command executed at a Cisco 2514 router.

Example 4-6 show version Command Output

A_StubR#show version

Cisco Internetwork Operating System Software

IOS (tm) 2500 Software (C2500-JS-L), Version 11.3(6), RELEASE SOFTWARE (fc1)

Copyright © 1986-1998 by cisco Systems, Inc.

Compiled Tue 06-Oct-98 22:17 by kpma

Image text-base: 0x03048CF4, data-base: 0x00001000

 

ROM: System Bootstrap, Version 5.2(8a), RELEASE SOFTWARE

BOOTFLASH: 3000 Bootstrap Software (IGS-RXBOOT), Version 10.2(8a),

RELEASE SOFTWARE (fc1)

 

A_StubR uptime is 25 minutes

System restarted by power-on

System image file is "flash:c2500-js-l_113-6.bin", booted via flash

 

cisco 2500 (68030) processor (revision D) with 4096K/2048K bytes of memory.

Processor board ID 04203139, with hardware revision 00000000

Bridging software.

X.25 software, Version 3.0.0.

SuperLAT software copyright 1990 by Meridian Technology Corp).

TN3270 Emulation software.

2 Ethernet/IEEE 802.3 interface(s)

2 Serial network interface(s)

32K bytes of non-volatile configuration memory.

16384K bytes of processor board System flash (Read ONLY)

 

Configuration register is 0x2102


The output of the show version command provides a valuable set of information. Depending on your type of router, different hardware configuration and non-standard software options are displayed by the show version command. The following paragraph focuses on the general output of this command:

On the first few lines of output, the show version command displays the IOS version number and its internal name. The IOS internal name tells you about its capabilities and options. In Example 4-6 the IOS version is 11.3(6) and its name is C2500-JS-L. For a description of the IOS naming convention for different routers, refer to Cisco Connection Online (CCO).

In the second section of the output, the Bootstrap software and the RXBOOT image versions are displayed.

Next, you can see the system uptime, how the system last restarted, and the image filename and where it loaded from (the image filename is modifiable and may not be the name it was originally given by Cisco Systems). Please note that if the router encounters errors (such as software crashes) that force the router to reload, that information (reason for reload) will be displayed here and it can be quite useful to the Cisco TAC engineer.

The section near the bottom provides hardware information (processor type, memory size, existing controllers) and non-standard software options.

The very last line of the show version command's output displays the value of the config-register in hex format.

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