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Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
Chapter12  -- troubleshooting networking problems
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Chapter12 -- troubleshooting networking problems

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Basic Networking Guide

Basic Networking Guide

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  • 1. Chapter 12: Troubleshooting Networking Problems Network+ Guide to Networks
  • 2. Objectives: <ul><li>Describe the elements of an effective troubleshooting methodology </li></ul><ul><li>Follow a systematic troubleshooting process to solve networking problems </li></ul><ul><li>Use a variety of software and hardware tools to diagnose problems </li></ul><ul><li>Discuss practical issues related to troubleshooting </li></ul>
  • 3. Troubleshooting Methodology <ul><li>Identify the Symptoms </li></ul><ul><li>Identify the Scope of the Problem </li></ul><ul><li>Establish What Has Changed </li></ul><ul><li>Determine the Most Probable Cause </li></ul><ul><ul><li>Verify user competency </li></ul></ul><ul><ul><li>Re-create the problem </li></ul></ul><ul><ul><li>Verify physical connectivity </li></ul></ul><ul><ul><li>Verify logical connectivity </li></ul></ul>
  • 4. Troubleshooting Methodology (continued) <ul><li>Recognize the potential effects of a solution </li></ul><ul><li>Implement a solution </li></ul><ul><li>Test the solution </li></ul><ul><li>Document the solution </li></ul>
  • 5. Troubleshooting Methodology (continued)
  • 6. Troubleshooting Methodology (continued) <ul><li>Identify the Symptoms </li></ul><ul><ul><li>Access to the network affected </li></ul></ul><ul><ul><li>Network performance affected </li></ul></ul><ul><ul><li>Data or programs affected </li></ul></ul><ul><ul><li>Only certain network services affected </li></ul></ul>
  • 7. Troubleshooting Methodology (continued) <ul><li>Identify the Symptoms (continued) </li></ul><ul><ul><li>If programs are affected, does the problem include one local application, one networked application, or multiple networked applications </li></ul></ul><ul><ul><li>What specific error messages do users report </li></ul></ul><ul><ul><li>One user or are multiple users affected </li></ul></ul><ul><ul><li>Do symptoms manifest themselves consistently </li></ul></ul>
  • 8. Troubleshooting Methodology (continued) <ul><li>Identify the Scope of the Problem </li></ul><ul><ul><li>How many users or network segments are affected? </li></ul></ul><ul><ul><ul><li>One user or workstation? </li></ul></ul></ul><ul><ul><ul><li>A workgroup? </li></ul></ul></ul><ul><ul><ul><li>A department? </li></ul></ul></ul><ul><ul><ul><li>One location within an organization? </li></ul></ul></ul><ul><ul><ul><li>An entire organization? </li></ul></ul></ul>
  • 9. Troubleshooting Methodology (continued) <ul><li>Identify the Scope of the Problem (continued) </li></ul><ul><ul><li>When did the problem begin? </li></ul></ul><ul><ul><ul><li>Has the network, server, or workstation ever worked properly? </li></ul></ul></ul><ul><ul><ul><li>Did the symptoms appear in the last hour or day? </li></ul></ul></ul><ul><ul><ul><li>Have the symptoms appeared intermittently for a long time? </li></ul></ul></ul><ul><ul><ul><li>Do the symptoms appear only at certain times? </li></ul></ul></ul>
  • 10. Troubleshooting Methodology (continued)
  • 11. Troubleshooting Methodology (continued)
  • 12. Troubleshooting Methodology (continued) <ul><li>Establish What Has Changed </li></ul><ul><ul><li>Did the operating system or configuration on a server, workstation, or connectivity device change? </li></ul></ul><ul><ul><li>Were new components added to a server, workstation, or connectivity device? </li></ul></ul><ul><ul><li>Were old components removed from a server, workstation, or connectivity device? </li></ul></ul><ul><ul><li>Were new users or segments added to the network? </li></ul></ul>
  • 13. Troubleshooting Methodology (continued) <ul><li>Establish What Has Changed (continued) </li></ul><ul><ul><li>Was a server, workstation, or connectivity device moved from its previous location to a new location? </li></ul></ul><ul><ul><li>Was a server, workstation, or connectivity device replaced? </li></ul></ul><ul><ul><li>Was new software installed on a server, workstation, or connectivity device? </li></ul></ul><ul><ul><li>Was old software removed from a server, workstation, or connectivity device? </li></ul></ul>
  • 14. Troubleshooting Methodology (continued) <ul><li>Select the Most Probable Cause </li></ul><ul><ul><li>Verify User Competency </li></ul></ul><ul><ul><li>Re-create the Problem </li></ul></ul><ul><ul><ul><li>Can you make the symptoms recur every time? </li></ul></ul></ul><ul><ul><ul><li>If symptoms recur, are they consistent? </li></ul></ul></ul><ul><ul><ul><li>Can you make the symptoms recur some of the time? </li></ul></ul></ul><ul><ul><ul><li>Do the symptoms happen only under certain circumstances? </li></ul></ul></ul>
  • 15. Troubleshooting Methodology (continued) <ul><li>Select the Most Probable Cause </li></ul><ul><ul><li>Re-create the Problem (continued) </li></ul></ul><ul><ul><ul><li>In the case of software malfunctions, are the symptoms consistent no matter how many and which programs or files the user has open? </li></ul></ul></ul><ul><ul><ul><li>Do the symptoms ever happen when you try to repeat them? </li></ul></ul></ul>
  • 16. Troubleshooting Methodology (continued) <ul><li>Select the Most Probable Cause </li></ul><ul><ul><li>Verify Physical Connectivity </li></ul></ul><ul><ul><ul><li>Symptoms of Physical Layer Problems </li></ul></ul></ul><ul><ul><ul><ul><li>Lengths exceed standards </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Noise affecting a signal </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Improper connections </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Damaged cables </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Faulty NICs </li></ul></ul></ul></ul>
  • 17. Troubleshooting Methodology (continued) <ul><li>Select the Most Probable Cause </li></ul><ul><ul><li>Verify Physical Connectivity </li></ul></ul><ul><ul><ul><li>Diagnosing Physical Layer Problems </li></ul></ul></ul><ul><ul><ul><ul><li>Device turned on </li></ul></ul></ul></ul><ul><ul><ul><ul><li>NIC properly inserted </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Device’s network cable properly connected </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Patch cables properly connect </li></ul></ul></ul></ul>
  • 18. Troubleshooting Methodology (continued) <ul><li>Select the Most Probable Cause </li></ul><ul><ul><li>Verify Physical Connectivity </li></ul></ul><ul><ul><ul><li>Diagnosing Physical Layer Problems (continued) </li></ul></ul></ul><ul><ul><ul><ul><li>Hub, router, or switch properly connected to the backbone </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Cables in good condition </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Connectors in good condition and properly seated </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Network lengths conform to specifications? </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Devices configured properly </li></ul></ul></ul></ul>
  • 19. Troubleshooting Methodology (continued) <ul><li>Select the Most Probable Cause </li></ul><ul><ul><li>Verify Physical Connectivity </li></ul></ul><ul><ul><ul><li>Swapping Equipment </li></ul></ul></ul><ul><ul><ul><ul><li>If you suspect a problem lies with a network component </li></ul></ul></ul></ul>
  • 20. Troubleshooting Methodology (continued)
  • 21. Troubleshooting Methodology (continued) <ul><li>Select the Most Probable Cause </li></ul><ul><ul><li>Verify Logical Connectivity </li></ul></ul><ul><ul><ul><li>Do error messages reference damaged or missing files or device drivers? </li></ul></ul></ul><ul><ul><ul><li>Do error messages reference malfunctioning or insufficient resources (such as memory)? </li></ul></ul></ul><ul><ul><ul><li>Has an operating system, configuration, or application been recently changed, introduced, or deleted? </li></ul></ul></ul><ul><ul><ul><li>Does the problem occur with only one application or a few, similar applications? </li></ul></ul></ul>
  • 22. Troubleshooting Methodology (continued) <ul><li>Select the Most Probable Cause </li></ul><ul><ul><li>Verify Logical Connectivity </li></ul></ul><ul><ul><ul><li>Does the problem happen consistently? </li></ul></ul></ul><ul><ul><ul><li>Does the problem affect a single user or one group of users? </li></ul></ul></ul>
  • 23. Troubleshooting Methodology (continued) <ul><li>Recognize the Potential Effects of a Solution </li></ul><ul><ul><li>Scope </li></ul></ul><ul><ul><li>Tradeoffs </li></ul></ul><ul><ul><li>Security </li></ul></ul><ul><ul><li>Scalability </li></ul></ul><ul><ul><li>Cost </li></ul></ul><ul><ul><li>Using Vendor Information </li></ul></ul>
  • 24. Troubleshooting Methodology (continued) <ul><li>Implement a Solution </li></ul><ul><ul><li>Implement a safe and reliable solution: </li></ul></ul><ul><ul><ul><li>1. Collect documentation about a problem’s symptoms </li></ul></ul></ul><ul><ul><ul><li>2. Backup existing software and keep the old parts handy </li></ul></ul></ul><ul><ul><ul><li>3. Perform the change and record your actions </li></ul></ul></ul><ul><ul><ul><li>4. Test your solution </li></ul></ul></ul>
  • 25. Troubleshooting Methodology (continued) <ul><li>Implement a Solution </li></ul><ul><ul><li>Implement a safe and reliable solution: </li></ul></ul><ul><ul><ul><li>5. Before leaving the area clean it up </li></ul></ul></ul><ul><ul><ul><li>6. Record the details you have collected about the symptoms, the problem, and the solution </li></ul></ul></ul><ul><ul><ul><li>7. If solution involved a significant change or problem, revisit the solution a day or two later to verify that the problem has been solved </li></ul></ul></ul>
  • 26. Troubleshooting Methodology (continued) <ul><li>Test the Solution </li></ul><ul><li>Document Problems and Solutions </li></ul><ul><ul><li>Staff Involved in Troubleshooting </li></ul></ul><ul><ul><li>Recording Problems and Resolutions </li></ul></ul>
  • 27. Troubleshooting Methodology (continued) <ul><ul><ul><li>A typical problem record form should include </li></ul></ul></ul><ul><ul><ul><ul><li>The name, department, and phone number of the problem originator </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Information regarding whether the problem is software- or hardware-related </li></ul></ul></ul></ul><ul><ul><ul><ul><li>If the problem is software-related, the package to which it pertains; if the problem is hardware-related, the device or component to which it pertains </li></ul></ul></ul></ul>
  • 28. Troubleshooting Methodology (continued) <ul><ul><ul><li>A typical problem record form should include (continued) </li></ul></ul></ul><ul><ul><ul><ul><li>Symptoms of the problem, including when it was first noticed </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The name and telephone number of the network support contact </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The amount of time spent troubleshooting the problem </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The resolution of the problem </li></ul></ul></ul></ul>
  • 29. Troubleshooting Methodology (continued) <ul><ul><li>Notifying Others of Changes </li></ul></ul><ul><ul><ul><li>A change management system </li></ul></ul></ul><ul><ul><ul><ul><li>Adding or upgrading software </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Adding or upgrading hardware or other devices </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Adding new hardware </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Changing the properties of a network device </li></ul></ul></ul></ul>
  • 30. Troubleshooting Methodology (continued) <ul><ul><li>A change management system (continued) </li></ul></ul><ul><ul><ul><li>Increasing or decreasing rights </li></ul></ul></ul><ul><ul><ul><li>Physically moving networked devices </li></ul></ul></ul><ul><ul><ul><li>Moving user accounts and their files/directories </li></ul></ul></ul><ul><ul><ul><li>Making changes in processes </li></ul></ul></ul><ul><ul><ul><li>Making changes in vendor policies or relationships </li></ul></ul></ul>
  • 31. Troubleshooting Methodology (continued) <ul><li>Preventing Future Problems </li></ul><ul><ul><li>Review the troubleshooting questions and examples </li></ul></ul><ul><ul><li>Predict network problems by network maintenance, documentation, security, or upgrades </li></ul></ul>
  • 32. Troubleshooting Tools <ul><li>Crossover Cable </li></ul><ul><ul><li>Use to directly interconnect two nodes </li></ul></ul><ul><li>Tone Generator and Tone Locator </li></ul><ul><ul><li>Tone generator is a small electronic device that issues a signal on a wire pair </li></ul></ul><ul><ul><li>Tone locator is a device that emits a tone when it detects electrical activity on a wire pair </li></ul></ul>
  • 33. Troubleshooting Tools (continued)
  • 34. Troubleshooting Tools (continued) <ul><li>Multimeter </li></ul><ul><ul><li>Can measure many characteristics of an electric circuit, including its resistance and voltage </li></ul></ul>
  • 35. Troubleshooting Tools (continued)
  • 36. Troubleshooting Tools (continued) <ul><li>Use a multimeter to: </li></ul><ul><ul><li>Verify that a cable is properly conducting electricity </li></ul></ul><ul><ul><li>Check for the presence of noise on a wire </li></ul></ul><ul><ul><li>Verify that the amount of resistance on coaxial cable </li></ul></ul><ul><ul><li>Test for short or open circuits in the wire </li></ul></ul>
  • 37. Troubleshooting Tools (continued) <ul><li>Cable Continuity Testers </li></ul><ul><ul><li>In troubleshooting a Physical layer problem, you may find the cause of a problem by simply testing whether your cable is carrying a signal to its destination </li></ul></ul>
  • 38. Troubleshooting Tools (continued)
  • 39. Troubleshooting Tools (continued) <ul><li>Cable Performance Testers </li></ul><ul><ul><li>Measure the distance to a connectivity device, termination point, or cable fault </li></ul></ul><ul><ul><li>Measure attenuation along a cable </li></ul></ul><ul><ul><li>Measure near-end crosstalk between wires </li></ul></ul><ul><ul><li>Measure termination resistance and impedance </li></ul></ul>
  • 40. Troubleshooting Tools (continued) <ul><li>Cable Performance Testers (continued) </li></ul><ul><ul><li>Issue pass/fail ratings for CAT 3, CAT 5, CAT 5e, CAT 6, or CAT 7 standards </li></ul></ul><ul><ul><li>Store and print cable testing results or directly save data to a computer database </li></ul></ul><ul><ul><li>Graphically depict a cable’s attenuation and crosstalk characteristics over the length of the cable </li></ul></ul>
  • 41. Troubleshooting Tools (continued)
  • 42. Troubleshooting Tools (continued) <ul><li>Network Monitors </li></ul><ul><ul><li>Continuously monitor network traffic on a segment </li></ul></ul><ul><ul><li>Capture network data transmitted on a segment </li></ul></ul><ul><ul><li>Capture frames sent to or from a specific node </li></ul></ul><ul><ul><li>Reproduce network conditions </li></ul></ul><ul><ul><li>Generate statistics about network activity </li></ul></ul>
  • 43. Troubleshooting Tools (continued) <ul><li>Network Monitors (continued) </li></ul><ul><ul><li>Discover all network nodes on a segment </li></ul></ul><ul><ul><li>Establish a baseline that reflects network traffic </li></ul></ul><ul><ul><li>Store traffic data and generate reports </li></ul></ul><ul><ul><li>Trigger alarms when traffic conditions meet preconfigured conditions </li></ul></ul>
  • 44. Troubleshooting Tools (continued) <ul><li>Abnormal data patterns and packets </li></ul><ul><ul><li>Local collisions </li></ul></ul><ul><ul><li>Late collisions </li></ul></ul><ul><ul><li>Runts </li></ul></ul><ul><ul><li>Giants </li></ul></ul>
  • 45. Troubleshooting Tools (continued) <ul><li>Abnormal data patterns and packets (continued) </li></ul><ul><ul><li>Jabber </li></ul></ul><ul><ul><li>Negative frame sequence checks </li></ul></ul><ul><ul><li>Ghosts </li></ul></ul><ul><li>Protocol Analyzers </li></ul><ul><ul><li>Can capture traffic </li></ul></ul><ul><ul><li>Can also analyze frames </li></ul></ul><ul><ul><li>To Layer 7 of the OSI Model </li></ul></ul>
  • 46. Troubleshooting Tools (continued)
  • 47. Troubleshooting Tools (continued) <ul><li>Wireless Network Testers </li></ul><ul><ul><li>Learn about a wireless environment by viewing the wireless network connection properties on your workstation </li></ul></ul>
  • 48. Troubleshooting Tools (continued)
  • 49. Troubleshooting Tools (continued) <ul><li>Wireless network testing tools </li></ul><ul><ul><li>Identify transmitting APs, stations and channels </li></ul></ul><ul><ul><li>Measure signal strength and range </li></ul></ul><ul><ul><li>Indicate the effects of attenuation, signal loss, and noise </li></ul></ul><ul><ul><li>Interpret signal strength information </li></ul></ul>
  • 50. Troubleshooting Tools (continued) <ul><li>Wireless network testing tools (continued) </li></ul><ul><ul><li>Ensure proper association and reassociation </li></ul></ul><ul><ul><li>Capture and interpret traffic </li></ul></ul><ul><ul><li>Measure throughput and assess data </li></ul></ul><ul><ul><li>Analyze the characteristics of each channel </li></ul></ul>
  • 51. Troubleshooting Tools (continued)
  • 52. Chapter Summary <ul><li>Before you can resolve a network problem, you need to determine its cause </li></ul><ul><li>Act like a doctor diagnosing a patient </li></ul><ul><li>Identify the scope of the problem </li></ul><ul><li>At each point, stop to consider </li></ul><ul><li>Ensure that the user is performing all functions correctly </li></ul>
  • 53. Chapter Summary (continued) <ul><li>Attempt to reproduce the problem’s symptoms </li></ul><ul><li>Check for sound connections </li></ul><ul><li>Exchange component for a functional one </li></ul><ul><li>Determine properly configured software </li></ul><ul><li>Consult vendor information </li></ul>
  • 54. Chapter Summary (continued) <ul><li>Test your solution </li></ul><ul><li>Operate a help desk </li></ul><ul><li>Use a software program for documenting </li></ul><ul><li>Record details about a problem </li></ul><ul><li>Follow up </li></ul>
  • 55. Chapter Summary (continued) <ul><li>Change management system </li></ul><ul><li>Tone generator and tone locator </li></ul><ul><li>Multimeter </li></ul><ul><li>Cable continuity testers </li></ul><ul><li>Cable performance tester </li></ul>
  • 56. Chapter Summary (continued) <ul><li>Network monitor </li></ul><ul><li>Protocol analyzers </li></ul><ul><li>Wireless network testing tools </li></ul>

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