1. 9: Troubleshooting Your Network
Networking for Home & Small Business

2. I Want My Network! Troubleshooting process
Utilities for connectivity tests
Common hardware & connection issues
Working with the help desk

3. Troubleshooting Identifying, locating and correcting problems
Not a trial & error!
Too much wasted time
Take documentation
The problem encountered
Steps taken to determine the cause of the problem
Steps to correct the problem and ensure that it will not reoccur

4. Step 1 Verify problem & GATHER INFO Question users
What happened? Any error messages? What web site did you type in?
What equipment is involved?
Any recent changes to config?
Gather brand/model, warranty info
Gather network info
In you have tools, monitor network for errors

5. Why do this? 90% of your job!!! If you get a help desk call…
JOB SECURITY
Keeps users happy when working
If you get a help desk call…
You need a plan!

6. Scenario
PC is down.
Need to finish sales report they were working on & it’s due at 11am.
Now what???
What could the problems be?
Now compare to the OSI model

7. Troubleshooting Method 1
Top-down
Application layer down
Starts near the user
Looking for problems in applications
Maybe a configuration problem in IE
Is it just one application that is not functioning, or do all applications fail?
For example, can the user access various web pages on the Internet, but not ?
Do other workstations have similar issues?

8. Troubleshooting Method 2
Bottom-up
Starts at Physical layer & then up
Good for novice
Could take longer to solve problems
Hardware & wires
Have cables been pulled out of their sockets?
If the equipment has indicator lights, are they on or off?

9. Troubleshooting Method 3
Divide-and-conquer
More experienced people
Start at middle layers & work up/down from there
Check IP address

10. Troubleshooting Method 4
Trial & Error
Make an educated guess based on past experience
If doesn’t work, you use that info to try something else
Relies on your abilities & experience
This actually could slow you down

11. Troubleshooting Method 5
Substitution
Problem is specific to a piece of hardware
Can save time for user
You must have the available parts
Could be expensive
Doesn’t always happen

12. At Home Would you keep spare equipment, like an extra router?
Would you be running network monitors?
Should you keep documentation of problems, upgrades & software versions?

13. Activity

14. Let’s Get Physical! Many problems are hardware related Use your senses
Vision, smell, touch and hearing

15. Utilities!

16. Could it be a DHCP issue?
Ipconfig
Ipconfig /all, release, renew

17. Activity
Packet Tracer Lab,

18. May I Ping You? Ok, you have an IP Can you ping something?
Can also test DNS (ping

19. Now What? You have an IP You can ping the destination
Must be a problem in the application
Like IE
You can NOT ping
Start pinging closer to you
Try default gateway 1st
YES: problem in not local
NO: problem is in local network

20. Ping Example

21. Ping Options

22. Activity
Packet Tracer Lab

23. Tracert Shows path of routers (hops) Can identify where the error is
30 hops max; you can change -h

24. Netstat
Shows protocols used, port number, local & foreign address

25. Nslookup
Is the DNS server properly translating names to IP addresses?

26. More Issues Wired & Wireless Ping from each to DG & to each other
Check the Router

27. Router/AP
Check the LED

28. Check the Cables! Straight-through, crossover? Bad connection?
Too long?

29. What’s Wrong Here?

30. WLAN Problems a/b/g/n compatibility Signal strength Interference
SSID, Authentication, Encryption= MATCH!
SSID case sensitive
Keys don’t match
# of clients to channels
Do & Packet Tracer

31. What’s Wrong Here?

32. Activity

33. Your LAN works, but… No ISP connection Check modem Ping web site
Ping another web site
Are any access-lists set up?

34. SOS
Other resources of help

35. Help Desk
Provides assistance to determine if a problem exists, the nature of the problem, and the solution.
Can run remote diagnostics
Get all their info & document
What solved problem
What steps worked & didn’t work

36. 9: Troubleshooting Your Network
Networking for Home & Small Business