1. Network Troubleshooting

2. Overview
A network administrator’s job has many aspects, all of which must be mastered through experience and education. Troubleshooting network problems is no exception. Some administrators can easily hone in on a problem; others take a while to get the hang of it. There simply is no magic wand for troubleshooting—each administrator needs to become very familiar with their network and how it should act.

3. Topics
Troubleshooting Models TCP/IP Troubleshooting Utilities Hardware Troubleshooting Tools System Monitoring Tools Network Baselining

4. First Things First Check the obvious Check the trouble indicators
Correct syntax
User error
Correct components
Correct configuration
Check the trouble indicators
Warning lights
Error messages and log files
Is the problem hardware or software?
Is the problem a single or multiple workstation?
Check the cables
June 20, 2011

5. Troubleshooting
Recognition
Diagnosis
Resolution

6. Troubleshooting Models
Step-by-step approach
Administrator

7. The CompTIA Network+ Troubleshooting Model
1. Establishing the symptoms and potential causes 2. Identifying the affected area 3. Establishing what has changed 4. Selecting the most probable cause 5. Implementing an action plan and solution 6. Testing the result 7. Identifying the results and effects of the solution 8. Documenting the solution and process

8. The Network+ Troubleshooting Model – Step 1
1. Establishing the symptoms and potential causes
Gather information
Re-create the problem
List potential causes
2. Identifying the affected area
3. Establishing what has changed
4. Selecting the most probable cause
5. Implementing an action plan and solution
6. Testing the result
7. Identifying the results and effects of the solution
8. Documenting the solution and process

9. The Network+ Troubleshooting Model – Step 2
1. Establishing the symptoms and potential causes
2. Identifying the affected area
One user
Several users
One server
One segment
The network
3. Establishing what has changed
4. Selecting the most probable cause
5. Implementing an action plan and solution
6. Testing the result
7. Identifying the results and effects of the solution
8. Documenting the solution and process

10. The Network+ Troubleshooting Model – Step 3
1. Establishing the symptoms and potential causes
2. Identifying the affected area
3. Establishing what has changed
Could you ever do this?
When did things change?
What has changed?
4. Selecting the most probable cause
5. Implementing an action plan and solution
6. Testing the result
7. Identifying the results and effects of the solution
8. Documenting the solution and process

11. The Network+ Troubleshooting Model – Step 4
1. Establishing the symptoms and potential causes
2. Identifying the affected area
3. Establishing what has changed
4. Selecting the most probable cause
Start with most obvious cause
Work backward
Try simple solutions
5. Implementing an action plan and solution
6. Testing the result
7. Identifying the results and effects of the solution
8. Documenting the solution and process

12. The Network+ Troubleshooting Model – Step 5
1. Establishing the symptoms and potential causes
2. Identifying the affected area
3. Establishing what has changed
4. Selecting the most probable cause
5. Implementing an action plan and solution
Create a plan
Determine potential effects of the plan
Implement step by step
6. Testing the result
7. Identifying the results and effects of the solution
8. Documenting the solution and process

13. The Network+ Troubleshooting Model – Step 6
1. Establishing the symptoms and potential causes
2. Identifying the affected area
3. Establishing what has changed
4. Selecting the most probable cause
5. Implementing an action plan and solution
6. Testing the result
Verify that it solved the problem
Verify that no new problems introduced
Test various conditions
7. Identifying the results and effects of the solution
8. Documenting the solution and process

14. The Network+ Troubleshooting Model – Step 7
1. Establishing the symptoms and potential causes
2. Identifying the affected area
3. Establishing what has changed
4. Selecting the most probable cause
5. Implementing an action plan and solution
6. Testing the result
7. Identifying the results and effects of the solution
Re-examine your list of potential effects
Test for potential effects
Adjust if needed
8. Documenting the solution and process

15. The Network+ Troubleshooting Model – Step 8
1. Establishing the symptoms and potential causes
2. Identifying the affected area
3. Establishing what has changed
4. Selecting the most probable cause
5. Implementing an action plan and solution
6. Testing the result
7. Identifying the results and effects of the solution
8. Documenting the solution and process
Use a troubleshooting template
Document all information
Maintain records for reference

16. Troubleshooting IP Configuration
Incorrect IP configuration

17. Troubleshooting with Ping
Ping to local system succeeds
Ping to default gateway fails

18. Troubleshooting with Tracert
Start troubleshooting
at last valid connection

19. Troubleshooting with Arp
Incorrect mapping

20. Troubleshooting with Telnet1
Upper-level service fails 2
Use Telnet to connect
C:\> telnet
Password:

21. Troubleshooting with Nbtstat
Server service running as desired

22. Troubleshooting with Netstat
Queue shows activity
No adapter errors
Connection valid
Listening ports valid

23. Troubleshooting with FTP
Patches and utilities
Vendor FTP site
FTP client

24. Troubleshooting with Nslookup
Verify default server
Verify that server is responding to queries
Verify that server can resolve names

25. Network Technician’s Hand Tools
Various small hand tools

26. Electrical Safety Rules
Professionals should service high-power equipment
Always disconnect before servicing
Work with a partner
Never bypass safety devices
Use anti-static devices

27. Wire Crimpers
Specific to media type

28. Strips insulation and embeds wire
A Punch Down Tool
OV #: 16-24
Source File Name(s): Will need photo – here’s a sample from google
Figure File Name: F png
Comments: Nancy to add callouts when photos are taken.
Strips insulation and embeds wire

29. Displays circuit status
A Circuit Tester
Plugs into socket
Displays circuit status
OV #: 16-25
Source File Name(s): Will need photo – sample from Google here
Figure File Name: F png
Comments: Nancy to add callouts when photos are taken.

30. Voltmeters
Digital
Analog

31. Ports for network cable Adapters for different network types
A Cable Tester
Ports for network cable
Displays media status
OV #: 16-27
Source File Name(s): Will need photo – here’s a sample from google
Figure File Name: F png
Comments: Nancy add callouts with photo
Adapters for different network types

32. Wires crossed over internally
Crossover Cables
OV #: 16-28
Source File Name(s): THIS PHOTO needs replacing – need to show both ends of cable.
Figure File Name: F png
Comments: Nancy add callouts with photo
Wires crossed over internally

33. A Hardware Loopback Plug
OV #: 16-29
Source File Name(s): Will need photo – here’s a sample from google
Figure File Name: F png
Comments: Nancy add callouts with photo
Crosses over transmit/receive lines

34. LED Indicator Lights Link light Activity light OV #: 16-30
Source File Name(s): Will need photo – can shoot back of any PC, use Nancy’s laptop if needed
Figure File Name: F png
Comments: Add callouts with photo

35. Tone Generators and Tone Locators
Probe detects signal
Port for network cable
OV #: 16-31
Source File Name(s): Will need photo – here’s a sample from google
Figure File Name: F png
Comments: add callouts with photo
Tone generator
Tone locator

36. Network Analyzers Network Analyzers Protocol analyzers
Windows 2000 = Network monitor
Novell = LANalyzer
Other third party
Protocol analyzers
Evaluate the data at all layers of the OSI model
Operate in promiscuous mode

37. A Performance Monitor
Displays
results
Nov. 8, 2014
Monitors
counters

38. Displays frame contents
A Protocol Analyzer
Captures frames
Displays frame contents

39. The Protocol Analysis Process
Capture frames
Decode contents
Analyze contents

40. Using the Baseline
Predict the impact of changes to network
Use to find the reason for degradation in performance
Show best locations to invest money in the network

41. Record of normal performance
A Baseline
Record of normal performance
Various tests
Baseline
Record of current performance
Basis for identifying abnormal conditions
Starting point for improving performance

42. 8. Upgrade or reconfigure
The Baseline Process
1. Evaluate network
8. Upgrade or reconfigure
as needed
2. Design tests
7. Repeat tests when
performance low
3. Schedule tests
4. Run tests
6. Analyze data
5. Document results

43. Renewing the Baseline
When do you redo your baseline?
When role of network changes
When services are added to network
When services are removed from network

45. Reflective Questions
Describe a troubleshooting situation you were involved in, or that you read or heard about. Was it resolved through a structured methodology?
Which of the troubleshooting tools and processes presented in this lesson do you think you will find most useful or use most frequently? Why?

46. Collect, Isolate, and Correct Model
Collect information
Isolate the problem
Correct the problem

47. Tools help you troubleshoot only if you have mastered their use
Network Support Tools
Tools help you troubleshoot only if you have mastered their use
Software-based tools
Diagnostic utilities
Performance monitors
TCP/IP Utilities