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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Chapter12 -- troubleshooting networking problems Presentation Transcript

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