Home > Articles > Cisco Certification > CCNP > Applying Cisco Troubleshooting Tools

Applying Cisco Troubleshooting Tools

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: Nov 16, 2001.

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.

Q&A

The answers to the following questions can be found in Appendix A. Some of the questions in this section are repeated from the "Do I Know ThisAlready" Quiz so that you can gauge the advancement of your knowledge of this subject matter.

1. Briefly explain why Cisco IOS troubleshooting commands and tools need proper handling.

2 What does proper handling of troubleshooting tools entail?

3 Define switching and specify whether it is considered a complex task.

4 Define routing and compare its complexity to switching.

5 List the sources of information used by a routing process for building its routing table.

6 When a packet is process-switched, what major tasks are performed?

7 Provide a short and generic explanation for route caching (or fast switching) and the purpose behind it.

8 Which of the route caching methods are not enabled by default? And from which configuration mode (prompt level) can they be enabled?

9 On which component of the Cisco 7000 router is the Fast Switch Cache located?

10 Name the two major components that participate in the routing and switching tasks within a Cisco 7000 router.

11 What is the difference between the Silicon Switch Processor (SSP) and the Switch Processor (SP) with respect to the switching cache options?

12 What is the command for enabling IP fast switching on an interface?

13 What is the command for enabling IP autonomous switching on a Cisco 7000 series router interface?

14 What is the command for enabling IP silicon switching on a Cisco 7000 series router (with SSP) interface?

15 With regard to speed and switching optimization, how did Cisco Systems improve the Cisco 7500 routers in comparison to the 7000 series?

16 What switching method (route caching) can be enabled on the 7000/7500 series routers' VIP cards?

17 On which Cisco router models is Netflow switching supported? (Specify the IOS version.)

18 What information does Netflow use as the basis of identifying a flow?

19 Briefly describe the advantages of Netflow switching. Also specify whether there should be any precautions with respect to enabling Netflow switching.

20 What is the command for enabling IP Netflow switching on a supported router interface?

21 What are the only switching (route caching) options on the 4000, 3000, and 2500 series routers?

22 The output of which command includes information about whether fast switching is enabled/disabled for a particular protocol on a particular interface?

23 Which command can be used to see the statistics on the number of packets that are process switched and fast switched?

24 Provide at least three examples of operations or packet types that are process switched.

25 What are some facts about the debug privileged exec mode command that one must keep in mind before using it?

26 Which service must be loaded if you need to see a timestamp with each of the debug output lines? (Also provide the command syntax.)

27 What command enables you to see the debug output from within a Telnet session?

28 Compare debugging with the packet option to debugging with the events option.

29 Which command enables debugging for all protocols and activities? Are there any concerns regarding usage of this command?

30 Before you enable debugging on a router, you are encouraged to check the router's CPU utilization. What is the command that allows you to do that? If the utilization is above 50%, are you encouraged to debug packets or to debug events?

31 Specify the command syntax for enabling debugging for those IP packets that satisfy (are permitted by) an access list 100.

32 What is the default setting (for example, enabled/disabled, default destination) for message logging?

33 How do the logging message destination options compare in terms of the overhead they introduce to a router?

34 Which Cisco IOS router command turns console logging on and specifies the level of logging to be directed to the console?

35 By using which Cisco IOS router command can you enable sending logging messages to the internal buffer and specify the level of logging desired to be buffered?

36 Specify the Cisco IOS router command that enables sending logging messages to the virtual terminal sessions and specifies the level of logging desired to be directed to the virtual terminal lines.

37 What Cisco IOS router command would you use to make a router's logging messages be sent to a syslog server at IP address 10.1.2.3?

38 What Cisco IOS router command would you use to make virtual terminal lines receive logging messages at the errors level and higher (i.e., errors, critical, alerts, emergencies)?

39 What is the severity of the following logging message?

%TR-3-WIREFAULT:Unit[0],wirefault:check the lobe cable MAU connection

40 What information does the output of the show logging Cisco IOS exec command display?

41 What are your choices in order to make your Cisco IOS router generate Novell-compliant (ipx) pings?

42 In which situation (loss of functionality, crash, or performance degradation) will the output of the show stack command most likely be asked for?

43 The outputs of the show memory and the show processes [cpu] commands will most likely be asked for in which situation (loss of functionality, crash, or performance degradation)?

44 In which situation (loss of functionality, crash, or performance degradation) will you most likely be asked to produce and provide a core dump for the technical support representative?

45 Which show command conveniently produces output equivalent to the output of show version, show running-config, show controllers, and a few other show commands?

46 Which Cisco IOS router command's output displays the current setting (value) of the config-register?

47 What is the outcome of not having an allocated and free buffer available for a packet?

48 Explain the role of the parameter called Permanent in buffer management.

49 Explain the role of the parameter called Max-Free in buffer management.

50 Explain the role of the parameter called Min-Free in buffer management.

51 Explain the role of the parameter called Initial in buffer management.

52 If the output of show buffer command displays a large number of misses, increasing the value of which one of the buffer management parameters (Permanent, Min-Free, Max-Free, Initial) will most likely remedy the situation?

53 What does the number of failures displayed on the output of show buffer command indicate?

54 Using what command can you find out the allocation of interface buffers on the Switch Processor of the Cisco 7x00 series routers?

55 What does the show buffers command display?

56 Which Cisco IOS command's output displays statistics about router memory (for example, amount of free processor memory)?

57 What information does the output of the Cisco IOS show processes exec command display?

58 The show processes command's output provides two numbers separated by a slash (for example, 4%/4%) for the CPU utilization over the last five seconds. How are those numbers interpreted?

59 Specify the command (with appropriate parameters) that displays the five-seconds, one-minute, and five-minute CPU utilization for each of the active processes.

60 What information can be gathered from the output of the Cisco IOS show stacks exec command?

61 Which command allows you to generate a core dump without reloading?

62 To ensure that a core dump can be sent to a server and saved successfully, what are some of the preliminary tasks and tests you must perform?

63 Which command causes the router to attempt to produce a core dump when it crashes?

64 By default, what is the name of the file that the core dump is written to?

65 Which command allows you to change the name of the core file?

Return to Beginning Previous Section

Cisco Press Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Cisco Press and its family of brands. I can unsubscribe at any time.

Overview

Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Cisco Press products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@ciscopress.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security

Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children

This site is not directed to children under the age of 13.

Marketing

Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out

Users can always make an informed choice as to whether they should proceed with certain services offered by Cisco Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.ciscopress.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links

This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020