Troubleshooting

Unit objectives Explain the basic troubleshooting

steps and prepare toolkits for troubleshooting

Troubleshoot the physical and logical network

Implement a network troubleshooting methodology based on a given scenario

Topic A Topic A: Troubleshooting basics Topic B: Troubleshooting the network Topic C: Troubleshooting scenarios

Troubleshooting Gather information Identify the affected areas of the

network Determine if anything has changed Establish the most probable cause Determine if escalation is necessary Create an action plan and a solution Implement and test the solution Document the solution

Information gathering Listen carefully Ask open-ended questions Recognize relevant information Look for unreported past errors Try quick fixes Speak in a professional manner

Identify the affected area Identify the users affected Determine priority Re-create the problem Rely on intuitive logical processes

Determine if anything has changed

Identify recent changes Compare current situation to

– Wiring schematics– Physical and logical network diagrams– Baselines– Policies and procedures

Establish probable cause Isolate and select the most likely source of

problem Eliminate obvious problems sequentially Determine scope of probable cause

– Does the problem exist across the enterprise?– Is the problem related to the logical

arrangement of resources?– Does the problem exist across a WAN link?– Does the problem exist in the local area

network?– Does the problem exist at the workstation?

Determine if escalation necessary

Can’t repair every problem alone Which level of support is necessary? Who needs to help fix the problem?

Create an action plan Determine appropriate course of

action Create a formal plan for large

problems

Implement and test a solution Be aware of operational needs Use troubleshooting tools Contact third-party service provider Test the solution you implemented Look at underlying factors

Identify results and effects Identify results of solution and any

effects Are things back to normal, or has

environment changed?

Document problem and solution Document symptoms, cause, solution,

and troubleshooting process Modify change-management

documentation Look for additional problems Provide feedback to users

Activity A-1

Discussing troubleshooting procedures

Problem and resolution tracking Tracking options Help desk software

Activity A-2

Tracking problems and resolutions

Hardware toolkit Screwdrivers Pliers Tweezers Grabber Flashlight Antistatic bags Containers Grounding straps and mats Antistatic sprays

Additional tools Multimeter Nut drivers Cable stripper Snips Punch down tool Crimper Butt set TDR OTDR Certifier Temperature monitor Voltage event recorder

Software toolkit Drivers on a disk Virus software Boot disk Operating system CD or DVD Common problems list

Activity A-3

Identifying common toolkit components

Topic B Topic A: Troubleshooting basics Topic B: Troubleshooting the network Topic C: Troubleshooting scenarios

Troubleshooting wired connections

Electrical interference Network noise Crosstalk

– Near End Crosstalk– Far End Crosstalk– Equal Level Far End Crosstalk– Pair to Pair Crosstalk

Attenuation Collisions Open impedance mismatch

Cable testing devices Test the physical cable Test connections and network functions

Physical cable tests Locate miswired cables, open cables,

and shorts Locate missing cables Locate unsupported cables Test hub connections Test PC connections Test installed cables Test patch cables Locate inactive cables

Network function tests Verifying if PC is ON, if it appears as a PC,

and maximum speed Verifying if hub is ON, if it appears as a hub,

and maximum speed Verifying PC to hub speed and data

transmission and port speed or duplex mismatch

Verifying hub to hub data transmission Determining if straight-thru or crossover

patch cable is required Finding speed bottlenecks on LANs Monitoring LAN link between two devices

Network analyzer Identify problems with

– Cabling– Jacks– Network cards– Hubs– Lower-level OSI hardware– TCP/IP

Activity B-1

Testing the physical network

Troubleshooting wireless Identify components to troubleshoot Isolate the problem Common problems

– Infrared– Radio– Bluetooth

Windows Network Diagnostics

Activity B-2

Troubleshooting wireless networking

TCP/IP utilities ARP ARP ping DIG Getmac Host Ifconfig Ipconfig FTP Mtr Nbstat Netstat Nslookup Ping Route Telnet Traceroute

Activity B-3

Identifying TCP/IP utilities used for troubleshooting

Ipconfig Use to display and modify TCP/IP

properties– /all– /release– /renew– /flushdns– /displaydns– /registerdns

Unix Ifconfig Unix command to display IP

addressing information Enable and disable network cards

Activity B-4

Using Ipconfig to display TCP/IP settings

Ping Packet Internet Groper Sends packet to another computer to test

connectivity Use NetBIOS name, DNS name, or IP

address

Ping troubleshooting If you tried to ping using a domain name,

use the IP address of the remote host instead

Try to ping a different computer Can’t communicate, use ipconfig to verify

that the computer has been assigned an IP address

Verify all network configuration settings Reboot the computer to verify that TCP/IP

has been loaded Try removing TCP/IP and reinstalling it Check the physical connections

Activity B-5

Testing TCP/IP connectivity

NSLookup and Tracert NSLookup

– Verifies communication with a DNS server

– Single or multiple DNS servers Tracert

– Verify network path between two computers

Activity B-6

Using NSLookup and Tracert

Windows Network Diagnostics Built in to Windows Vista and Windows

Server 2008 Automates troubleshooting Diagnose and repair problems

automatically

Activity B-7

Troubleshooting with Network Diagnostics

Topic C Topic A: Troubleshooting basics Topic B: Troubleshooting the network Topic C: Troubleshooting scenarios

Remote Desktop components The Windows computer on which

you’ve enabled Remote Desktop The configuration of Remote Desktop

itself The computer with which you’re

connecting to the remote Windows computer

The DNS server The physical network

Activity C-1

Troubleshooting Remote Desktop connectivity

Activity C-2

Troubleshooting the inability of a user to access a shared resource

Activity C-3

Troubleshooting access to an account

Activity C-4

Troubleshooting hardware problems

Activity C-5

Troubleshooting a network problem related to adding or removing services

Unit summary Explained the basic troubleshooting

steps and prepared toolkits for troubleshooting

Troubleshot the physical and logical network

Implemented a network troubleshooting methodology based on a given scenario