9: troubleshooting your network networking for home & small business
TRANSCRIPT
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9: Troubleshooting Your Network
Networking for Home & Small Business
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I Want My Network!
• Troubleshooting process
• Utilities for connectivity tests
• Common hardware & connection issues
• Working with the help desk
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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
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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
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Why do this?
• 90% of your job!!!– JOB SECURITY– Keeps users happy when working
• If you get a help desk call…– You need a plan!
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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
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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 email?
• Do other workstations have similar issues?
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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?
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Troubleshooting Method 3
• Divide-and-conquer– More experienced people
– Start at middle layers & work up/down from there
• Check IP address
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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
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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
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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?
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Activity
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Let’s Get Physical!
• Many problems are hardware related
• Use your senses– Vision, smell, touch and hearing
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Utilities!
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Could it be a DHCP issue?
• Ipconfig
• Ipconfig /all, release, renew
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Activity
• Packet Tracer Lab, 9.2.3.2
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May I Ping You?
• Ok, you have an IP– Can you ping something?– Can also test DNS (ping www.cisco.com)
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Now What?• You have an IP• You can ping the destination• Must be a problem in the application
– Like IE
• You have an IP• You can NOT ping• Start pinging closer to you
– Try default gateway 1st
– YES: problem in not local– NO: problem is in local network
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Ping Example
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Ping Options
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Activity
• Packet Tracer Lab 9.2.4.3
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Tracert
• Shows path of routers (hops)
• Can identify where the error is
• 30 hops max; you can change– -h
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Netstat
• Shows protocols used, port number, local & foreign address
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Nslookup
• Is the DNS server properly translating names to IP addresses?
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More Issues
• Wired & Wireless
• Ping from each to DG & to each other
• Check the Router
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Router/AP
• Check the LED
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Check the Cables!
• Straight-through, crossover?
• Bad connection?
• Too long?
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What’s Wrong Here?
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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 9.3.4.2 & 9.3.5.2 Packet Tracer
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What’s Wrong Here?
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Activity
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Your LAN works, but…
• No ISP connection
• Check modem
• Ping web site
• Ping another web site
• Are any access-lists set up?
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SOS
• Other resources of help
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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
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9: Troubleshooting Your Network
Networking for Home & Small Business