1. Lec4: Troubleshooting Network Problems Network+ Guide to Networks 5 th Edition Chapter 13 Troubleshooting Network Problems Organized by: Nada Alhirabi NET 311

2. Network+ Guide to Networks, 5 th Edition2 Objectives Describe the steps involved in an effective troubleshooting methodology Follow a systematic troubleshooting process to identify and resolve networking problems Document symptoms, solutions, and results when troubleshooting network problems Use a variety of software and hardware tools to diagnose problems

3. Definition - What does Network Troubleshooting mean? Network troubleshooting is the collective measures and processes used to identify, diagnose and resolve problems and issues within a computer network. It is a systematic process that aims to resolve problems and restore normal network operations within the network. Network troubleshooting can be a manual or automated task. When using automated tools, network management can be done using network diagnostic software. Techopedia explains Network Troubleshooting3

4. Network Troubleshooting Network troubleshooting is primarily done by network engineers or administrators to repair or optimize a network. It is generally done to recover and establish network or Internet connections on end nodes/devices. Some of the processes within network troubleshooting include but are not limited to: –Finding and resolving problems and establishing Internet/network connection of a computer/device/node –Configuring a router, switch or any network management device –Installing cables or Wi-Fi devices –Updating firmware devices on router switch –Removing viruses –Adding, configuring and reinstalling a network printer Techopedia explains Network Troubleshooting4

5. Network+ Guide to Networks, 5 th Edition5 Troubleshooting Methodology Proceed logically and methodically Follow recommended steps Use experience when necessary Logical approach benefits –Prevents wasteful, time-consuming efforts Unnecessary software, hardware replacements

6. Network+ Guide to Networks, 5 th Edition6 Troubleshooting Methodology (cont’d.) Troubleshooting steps –Identify symptoms, problems –Identify affected area –Determine what has changed –Establish most probable cause –Determine if escalation necessary –Create action plan, solution –Implement solution, test result –Identify results, effects –Document solution, process

7. Network+ Guide to Networks, 5 th Edition7 Help to Prevent Future Problems Avert network problems –Network maintenance –Documentation –Security –Upgrades

8. Network+ Guide to Networks, 5 th Edition8

9. 9 Troubleshooting Tools Utilities help troubleshoot network problems –Ping –Specialized tools Specifically designed to analyze, isolate network problems Simple continuity testers Protocol analyzers –Tool selection dependencies Problem being investigated Network characteristics

10. Network+ Guide to Networks, 5 th Edition10 Crossover Cable Crossover cable –Reverses transmit and receive wire pairs in one connector Directly interconnect two nodes without intervening connectivity device –Use Verify NIC transmitting, receiving signals properly

11. Network+ Guide to Networks, 5 th Edition11 Tone Generator and Tone Locator Ideal situation –Telecommunications closet ports, wire terminations all labeled properly Reality –Telecommunications closet disorganized, poorly documented Tone generator (toner) –Issues signal on wire pair

12. Network+ Guide to Networks, 5 th Edition12 Tone Generator and Tone Locator (cont’d.) Tone locator (probe) –Emits tone when electrical activity detected Probe kit –Generator and locator combination –Fox and hound Testing requires trial and error Use –Determine where wire pair terminates Not used to determine cable characteristics

13. Network+ Guide to Networks, 5 th Edition13 Tone Generator and Tone Locator (cont’d.) Figure 13-4 Use of a tone generator and tone locator

14. Network+ Guide to Networks, 5 th Edition14 Multimeter Tests cables for faults –Isolates problems with network cables Multimeter –Measures electric circuit characteristics Resistance and voltage Voltmeter –Measures electric circuit pressure, voltage Voltage creates signals over network wire

15. Multimeter (cont’d.) Resistance –Fundamental wire property Dependent on wire’s molecular structure, size –Measured in ohms Using ohmmeter Impedance –Resistance contributing to controlling signal –Measured in ohms –Telltale factor for ascertaining where cable faults lie –Some required for proper signal transmission and interpretation Network+ Guide to Networks, 5 th Edition15

16. Network+ Guide to Networks, 5 th Edition16 Multimeter (cont’d.) Multimeter –Separate instruments for measuring wires impedance, resistance, voltage –Has several uses –Sophistication, features, and costs vary Figure 13-5 A multimeter

17. Network+ Guide to Networks, 5 th Edition17 Cable Continuity Testers Cable checkers (continuity testers, cable testers) –Tests whether cable carrying signal to destination –Tests cable continuity Copper-based cable tester –Consists of two parts Base unit generates voltage Remote unit detects voltage Series of lights, audible tone –Signal pass/fail

18. Network+ Guide to Networks, 5 th Edition18 Cable Continuity Testers (cont’d.) Verify UTP, STP wires paired correctly –Not shorted, exposed, crossed Fiber optic continuity tester –Issues light pulses on fiber –Determines whether pulses reached other end –Tests the cable Test all cables to ensure meeting network’s required standards Offer convenience: portable, lightweight, low cost Figure 13-6 Cable continuity testers

19. Cable Performance Testers Determines if cable carrying current Continuity testers versus performance testers –Sophistication and price –Performance tester accomplishes same continuity, fault tests –Continuity testers perform additional tasks Sophisticated performance testers –Include TDR (time domain reflectometer) Issue signal, measures signal bounce back Indicate proper terminator installation, function, node distance Network+ Guide to Networks, 5 th Edition19

20. Network+ Guide to Networks, 5 th Edition20 Cable Performance Testers (cont’d.) Fiber-optic connections testers –Use OTDRs (optical time domain reflectometers) Transmit light-based signals of different wavelengths over fiber –OTDRs Measure fiber length Determine faulty splice locations, breaks, connectors, bends Measure attenuation over cable Expensive Figure 13-7 A cable performance tester

21. Network+ Guide to Networks, 5 th Edition21 Voltage Event Recorders Voltage event –Any condition where voltage exceeds or drops below predefined levels Voltage event recorder –Collects data about power quality Downloaded to workstation Analyzed by software –Cost up to $5000 Figure 13-8 Voltage event recorder

22. Network+ Guide to Networks, 5 th Edition22 Butt Set Lineman’s handset, telephone test set –Butt into telephone conversation –Rugged, sophisticated telephone Uses –Determine if line functioning Receiving signal, picking up noise affecting signal –Sophisticated butt sets Perform rudimentary cable testing –Detecting dial tone on line Figure 13-9 Butt set

23. Network Monitors Software-based tool –Continually monitors network traffic from server, workstation attached to network –Interprets up to Layer 3 –Determine protocols passed by each frame –Cannot interpret frame data Included in NOS –Microsoft’s Network Monitor Purchase or free download tools developed by other software companies –All use similar graphical interfaces Network+ Guide to Networks, 5 th Edition23

24. Network+ Guide to Networks, 5 th Edition24 Protocol Analyzers Protocol analyzer (network analyzer) –Captures traffic, analyzes frames Typically to Layer 7 Variety of protocol analyzer software available –Wireshark Same features as network monitor –Few extras –Generates traffic Sniffer (packet sniffer) hardware –Older term Figure 13-10 Traffic captured by a protocol analyzer

25. Network+ Guide to Networks, 5 th Edition25 Protocol Analyzers (cont’d.) Offers versatility in information type, depth –Could collect more information than can be reasonably processed –Set filters to avoid Before using network monitor or protocol analyzer –Learn what network traffic normally looks like Capture data for time period on regular basis

26. Network+ Guide to Networks, 5 th Edition26 Wireless Network Testers Tools containing wireless NICs, running wireless protocols Workstation wireless network connection properties –Shows a little about wireless environment Connection duration, signal speed and strength, number of packets exchanged –Only applies to one workstation Programs scan for wireless signals –Discover access points, wireless stations transmitting –Free

27. Network+ Guide to Networks, 5 th Edition27 Wireless Network Testers (cont’d.) Commercial tools advantages –Portability –Installed with wireless network analysis tools –Contain more powerful antennas Figure 13-11 Wireless network testing tool

28. Summary Methodical, logical troubleshooting methodology –Key to solving network problems Troubleshooting tools –Tone generator and tone locator –Multimeters –Basic cable continuity testers –Cable performance tester –Voltage event recorder –Butt set –Network monitors and protocol analyzers –Wireless network testing tools Network+ Guide to Networks, 5 th Edition28