OV 15 - 1 ght © 2013 Logical Operations, Inc. All rights reserved. Network Troubleshooting Network Troubleshooting Models Network Troubleshooting Utilities Hardware Troubleshooting Tools Common Connectivity Issues
Dec 27, 2015
OV 15 - 1Copyright © 2013 Logical Operations, Inc. All rights reserved.
Network Troubleshooting
Network Troubleshooting Models Network Troubleshooting Utilities Hardware Troubleshooting Tools Common Connectivity Issues
OV 15 - 2Copyright © 2013 Logical Operations, Inc. All rights reserved.
Troubleshooting
RecognitionRecognition DiagnosisDiagnosis ResolutionResolution
OV 15 - 3Copyright © 2013 Logical Operations, Inc. All rights reserved.
Troubleshooting Models
Step-by-step approachStep-by-step approach
Administrator
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The Network+ Troubleshooting Model
1. Identify the problem1. Identify the problem
2. Establish a theory of probable cause2. Establish a theory of probable cause
3. Test the theory to determine cause3. Test the theory to determine cause
4. Establish a plan of action to resolve the problem and identify potential effects4. Establish a plan of action to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary5. Implement the solution or escalate as necessary
6. Verify full system functionality and if applicable implement preventative measures6. Verify full system functionality and if applicable implement preventative measures
7. Document findings, actions, and outcomes7. Document findings, actions, and outcomes
OV 15 - 5Copyright © 2013 Logical Operations, Inc. All rights reserved.
Step 1: Identify the Problem
1. Identify the problem Question users Re-create the problem Identify symptoms Determine if anything has changed
2. Establish a theory of probable cause
3. Test the theory to determine cause
4. Establish a plan of action to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary
6. Verify full system functionality and if applicable implement preventative measures
7. Document findings, actions, and outcomes
OV 15 - 6Copyright © 2013 Logical Operations, Inc. All rights reserved.
Step 2: Establish a Theory of Probable Cause
1. Identify the problem
2. Establish a theory of probable cause Question the obvious
3. Test the theory to determine cause
4. Establish a plan of action to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary
6. Verify full system functionality and if applicable implement preventative measures
7. Document findings, actions, and outcomes
OV 15 - 7Copyright © 2013 Logical Operations, Inc. All rights reserved.
Step 3: Test the Theory to Determine Cause
1. Identify the problem
2. Establish a theory of probable cause
3. Test the theory to determine cause Determine next steps to resolve the problem
4. Establish a plan of action to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary
6. Verify full system functionality and if applicable implement preventative measures
7. Document findings, actions, and outcomes
OV 15 - 8Copyright © 2013 Logical Operations, Inc. All rights reserved.
Step 4: Establish a Plan of Action to Resolve the Problem and Identify Potential Effects
1. Identify the problem
2. Establish a theory of probable cause
3. Test the theory to determine cause
4. Establish a plan of action to resolve the problem and identify potential effects Establish a plan of action before you start making changes, once you have determined the
probable cause Detail each step that you will take while attempting to resolve the issue
5. Implement the solution or escalate as necessary
6. Verify full system functionality and if applicable implement preventative measures
7. Document findings, actions, and outcomes
OV 15 - 9Copyright © 2013 Logical Operations, Inc. All rights reserved.
Step 5: Implement the Solution or Escalate as Necessary
1. Identify the problem
2. Establish a theory of probable cause
3. Test the theory to determine cause
4. Establish a plan of action to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary Implement the plan of action step by step to fix the problem Or, escalate the issue to the appropriate personnel
6. Verify full system functionality and if applicable implement preventative measures
7. Document findings, actions, and outcomes
OV 15 - 10Copyright © 2013 Logical Operations, Inc. All rights reserved.
Step 6: Verify Full System Functionality and If Applicable Implement Preventative Measures
1. Identify the problem
2. Establish a theory of probable cause
3. Test the theory to determine cause
4. Establish a plan of action to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary
6. Verify full system functionality and if applicable implement preventative measures
7. Document findings, actions, and outcomes
OV 15 - 11Copyright © 2013 Logical Operations, Inc. All rights reserved.
Step 7: Document Findings, Actions, and Outcomes
1. Identify the problem
2. Establish a theory of probable cause
3. Test the theory to determine cause
4. Establish a plan of action to resolve the problem and identify potential effects
5. Implement the solution or escalate as necessary
6. Verify full system functionality and if applicable implement preventative measures
7. Document findings, actions, and outcomes
OV 15 - 12Copyright © 2013 Logical Operations, Inc. All rights reserved.
Troubleshooting with IP Configuration Utilities
Incorrect IP configurationIncorrect IP
configuration
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The ping Utility
Ping to localsystem succeeds
Ping to localsystem succeeds
Ping to default gateway failsPing to default gateway fails
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The traceroute Utility
Start troubleshootingat last valid connectionStart troubleshooting
at last valid connection
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The arp Utility
Incorrect IP address mappingIncorrect IP address mapping
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The NBTSTAT Utility
Servicerunning optimally
Servicerunning optimally
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The NETSTAT Utility
Queue shows activityQueue shows activity
No adapter errorsNo adapter errors
Connection validConnection valid
Listeningports validListening
ports valid
OV 15 - 18Copyright © 2013 Logical Operations, Inc. All rights reserved.
The Nslookup Utility
Verify default serverVerify default server
Verify that server is responding to queriesVerify that server is
responding to queries
Verify that server can resolve names
Verify that server can resolve names
OV 15 - 19Copyright © 2013 Logical Operations, Inc. All rights reserved.
SNIPS
System and Network Integrated Polling System (SNIPS) offers: Monitoring of UNIX systems Command-line and web interfaces Monitoring functions for network services
Determine status Report
Real-time reports Alarms and logs Four supported monitoring levels:
Info Warning Error Critical
OV 15 - 20Copyright © 2013 Logical Operations, Inc. All rights reserved.
Network Technician's Hand Tools
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Electrical Safety Rules
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 Perform only the work for which you have sufficient training Do not attempt repair work when you are tired Do not assume anything without checking it out for yourself Do not wear jewelry or other articles that could accidentally contact circuitry
and conduct current
OV 15 - 22Copyright © 2013 Logical Operations, Inc. All rights reserved.
Electrical Safety Rules (Cont.)
Electrical safety rules: Wear rubber-soled shoes to insulate yourself from ground Suspend work during an electrical storm Do not handle electrical equipment when your hands or feet are wet or when
you are standing on a wet surface Prevent static electricity from damaging components by standing on a totally
insulated rubber mat to increase the resistance of the path to ground
OV 15 - 23Copyright © 2013 Logical Operations, Inc. All rights reserved.
Wire Crimpers
Used to trim the ends of a cableUsed to trim the ends of a cable
OV 15 - 24Copyright © 2013 Logical Operations, Inc. All rights reserved.
Punch Down Blocks
There are two types of punch down blocks: 66 Block - Used for terminating telecommunications 110 Block - Used for structured wiring systems
OV 15 - 25Copyright © 2013 Logical Operations, Inc. All rights reserved.
Punch Down Tools
Strips insulation and embeds wireStrips insulation and embeds wire
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Circuit Testers
Displays circuit statusDisplays circuit status
Plugs into socketPlugs into socket
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Multimeters
Digital Analog
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Cable Testers
Adapters for different network types
Adapters for different network types
Displays media statusDisplays media status
Ports for network cable
Ports for network cable
OV 15 - 29Copyright © 2013 Logical Operations, Inc. All rights reserved.
Cable Certifiers
Cable Certifiers are: Used to perform tests
Cable testing Validity testing
Useful in finding short circuits and other faults Helpful in determining mode of connectivity devices
Full duplex Half duplex
OV 15 - 30Copyright © 2013 Logical Operations, Inc. All rights reserved.
Types of Cable Testers and Certifiers
Tester or Certifier Description
Certification tester
Determine if network meets ISO or TIA standards (Cat 5e, Cat 6
or Cat7) Use when copper and fiber media exist on network
Qualification tester Measure possible network data speeds Used for troubleshooting
LAN testers Test network speed, cable skew, cable propagation
delay, cable, attenuation, and cable verification
Network cable certifier
Test network speed and performance
OV 15 - 31Copyright © 2013 Logical Operations, Inc. All rights reserved.
Crossover Cables
Wires crossed over internally
Wires crossed over internally
OV 15 - 32Copyright © 2013 Logical Operations, Inc. All rights reserved.
Hardware Loopback Plugs
Crosses over transmit/receive lines
Crosses over transmit/receive lines
OV 15 - 33Copyright © 2013 Logical Operations, Inc. All rights reserved.
Time-Domain Reflectometers
Time-Domain Reflectometers: Used for detecting cable problems Sends an electrical signal out onto the wire and analyzes the signal on its
return Can detect:
Bends Short circuits Connector problems Termination problems on coax networks
Optical TDRs used for fiber optic cabling: Detect fiber length Determine location of faulty splices, breaks, and bends Measure attenuation
OV 15 - 34Copyright © 2013 Logical Operations, Inc. All rights reserved.
Tone Generators and Tone Locators
Probe detects signal
Probe detects signal
Tone generator Tone locator
Port for network cable
Port for network cable
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Environment Monitors
Environment monitors help maintain proper operational environment for
network equipment: Humidity Temperature
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Butt Sets
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LED Indicators
Link indicatorLink indicator
Activity indicatorActivity indicator
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Network Analyzers
Captures framesCaptures frames
Displayscaptured
frames andcontent
Displayscaptured
frames andcontent
OV 15 - 39Copyright © 2013 Logical Operations, Inc. All rights reserved.
Demarc
Responsibility of the Phone Company
Responsibility of the Property Owner
Outside Wire
Inside Wire
Wire distribution
device
Wire distribution
device
Demarcation pointDemarcation point
OV 15 - 40Copyright © 2013 Logical Operations, Inc. All rights reserved.
Wireless Testers
Wireless testers are: Wi-Fi spectrum analyzers used for detecting problems on WLANs Able to detect:
Wireless devices Points of interference Overall health of the WLAN
OV 15 - 41Copyright © 2013 Logical Operations, Inc. All rights reserved.
WLAN Survey Software
WLAN survey software: Used for:
Wireless planning Simulations
Implementations Simulates WLAN performance Can determine network coverage areas
OV 15 - 42Copyright © 2013 Logical Operations, Inc. All rights reserved.
Physical Issues
Physical connectivity issues include: Crosstalk Near-end crosstalk Attenuation Collisions Shorts Open impedance mismatches Interference Bad modules (SFPs, GBICs) Cable problems
OV 15 - 43Copyright © 2013 Logical Operations, Inc. All rights reserved.
Logical Issues
Logical connectivity issues include: Port speed Port duplex mismatches Incorrect VLAN assignment Incorrect IP address Wrong gateway assignment Wrong DNS server assignment Wrong subnet mask
OV 15 - 44Copyright © 2013 Logical Operations, Inc. All rights reserved.
Wireless Issues
Wireless connectivity issues include: Interference Incorrect encryption levels Channel congestion Incorrect frequency SSID mismatches Standard mismatches Distance Bounce Incorrect antenna placement Configurations Incompatibilities Incorrect channel Latency Incorrect switch placement
OV 15 - 45Copyright © 2013 Logical Operations, Inc. All rights reserved.
Routing and Switching Issues
Routing and switching issues that might need to be escalated include: Switching loop Routing loop Routing problem Proxy arp Broadcast storms Port configuration VLAN assignment Mismatched MTU/MUT blackhole
OV 15 - 46Copyright © 2013 Logical Operations, Inc. All rights reserved.
Reflective Questions
1. In your troubleshooting experience, what types of problems have you encountered? How did you diagnose the problems?
2. In your opinion, what are the common TCP/IP issues that you encounter during troubleshooting?