OV 15 - 1 Copyright © 2013 Logical Operations, Inc. All rights reserved. Network Troubleshooting Network Troubleshooting Models Network Troubleshooting

OV 15 - 1Copyright © 2013 Logical Operations, Inc. All rights reserved.

Network Troubleshooting

Network Troubleshooting Models Network Troubleshooting Utilities Hardware Troubleshooting Tools Common Connectivity Issues


Troubleshooting

RecognitionRecognition DiagnosisDiagnosis ResolutionResolution


Troubleshooting Models

Step-by-step approachStep-by-step approach

Administrator


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


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


Step 2: Establish a Theory of Probable Cause

1. Identify the problem

2. Establish a theory of probable cause Question the obvious







Step 3: Test the Theory to Determine Cause



3. Test the theory to determine cause Determine next steps to resolve the problem






Step 4: Establish a Plan of Action to Resolve the Problem and Identify Potential Effects




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





Step 5: Implement the Solution or Escalate as Necessary





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




Step 6: Verify Full System Functionality and If Applicable Implement Preventative Measures









Step 7: Document Findings, Actions, and Outcomes









Troubleshooting with IP Configuration Utilities

Incorrect IP configurationIncorrect IP

configuration


The ping Utility

Ping to localsystem succeeds

Ping to localsystem succeeds

Ping to default gateway failsPing to default gateway fails


The traceroute Utility

Start troubleshootingat last valid connectionStart troubleshooting

at last valid connection


The arp Utility

Incorrect IP address mappingIncorrect IP address mapping


The NBTSTAT Utility

Servicerunning optimally

Servicerunning optimally


The NETSTAT Utility

Queue shows activityQueue shows activity

No adapter errorsNo adapter errors

Connection validConnection valid

Listeningports validListening

ports valid


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


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


Network Technician's Hand Tools


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


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


Wire Crimpers

Used to trim the ends of a cableUsed to trim the ends of a cable


Punch Down Blocks

There are two types of punch down blocks: 66 Block - Used for terminating telecommunications 110 Block - Used for structured wiring systems


Punch Down Tools

Strips insulation and embeds wireStrips insulation and embeds wire


Circuit Testers

Displays circuit statusDisplays circuit status

Plugs into socketPlugs into socket


Multimeters

Digital Analog


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


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


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


Crossover Cables

Wires crossed over internally

Wires crossed over internally


Hardware Loopback Plugs

Crosses over transmit/receive lines

Crosses over transmit/receive lines


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


Tone Generators and Tone Locators

Probe detects signal

Probe detects signal

Tone generator Tone locator

Port for network cable

Port for network cable


Environment Monitors

Environment monitors help maintain proper operational environment for

network equipment: Humidity Temperature


Butt Sets


LED Indicators

Link indicatorLink indicator

Activity indicatorActivity indicator


Network Analyzers

Captures framesCaptures frames

Displayscaptured

frames andcontent

Displayscaptured

frames andcontent


Demarc

Responsibility of the Phone Company

Responsibility of the Property Owner

Outside Wire

Inside Wire

Wire distribution

device

Wire distribution

device

Demarcation pointDemarcation point


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


WLAN Survey Software

WLAN survey software: Used for:

Wireless planning Simulations

Implementations Simulates WLAN performance Can determine network coverage areas


Physical Issues

Physical connectivity issues include: Crosstalk Near-end crosstalk Attenuation Collisions Shorts Open impedance mismatches Interference Bad modules (SFPs, GBICs) Cable problems


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


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


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


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?

Documents

OV 15 - 1 Copyright © 2013 Logical Operations, Inc. All rights reserved. Network Troubleshooting Network Troubleshooting Models Network Troubleshooting