Network Network TroubleshootingTroubleshooting

Chapter 15Chapter 15

• Describe appropriate troubleshooting tools and their functions

• Analyze and discuss the troubleshooting process

• Tackle a variety of troubleshooting scenarios

ObjectivesObjectives

• Cable Testers, TDRs, and OTDRs – Devices to test for broken cables • Cable testers

– Detect continuity problems – Detects if a wire map isn’t correct

• b. TDRs – Time domain reflectometer – Identifies the location of a cable break – Works with copper cables

• OTDRs – Optical time domain reflectometers (OTDR) – Identifies the location of a cable break – Works with fiber-optic cables

• Wi-Fi protected access (WPA) A way of enabling wireless encryption – Certifiers • Only use for slowdowns, not for disconnects • Require a loopback on the far end of cable run • Ensure that a cable can handle its rated capacity

– Voltage Event Recorder/Temperature Monitor • Detect power and heat problems • Cause intermittent problems

• Protocol Analyzers – Monitor protocols at different layers – Application, Session, Network, and Data Link layers – Both hardware and software tools

• Cable Stripper/Snip – Enables you to make UTP cables – Also need crimpers – Often combined in one tool

• Multimeters – Test AC and DC voltage – Test resistance • Test continuity • A great fallback when you do not have a cable tester.

• Tone Probes and Tone Generators – Work together to identify opposite ends of unlabeled

cable runs – Tone generator puts a signal (tone) on wire – Tone probe on opposite end detects the signal

• Butt Sets – Hand set – Use to tap into a 66- or 100-block to test a line

• 8. Punchdown Tools – Put UTP wires into 66- and 110-blocks – Repunch a connection to make sure contacts are

set

• Software tools – TRACERT/TRACEROUTE • Traces all routers between two points • Use to discover where a problem lies

• Displays IP settings – IPCONFIG without parameters • Basic information only

– Ipconfig /all gives configuration details

• PING and ARP PING – PING • Queries by name or IP address • Uses ICMP packets • Works across routers • Problem: devices can block ICMP

• ARP PING – Queries by IP address – Uses ARP packets – Problem: does not cross routers – Only on UNIX and UNIX-like systems

• NSLOOKUP/DIG – Both diagnose DNS problems – NSLOOKUP (all operating systems) • Poor tool • Considered obsolete • Without switches provides name (if available) and IP

address of default DNS server

• DIG (everyone but Windows) – More powerful