This document discusses various tools used for network troubleshooting, including cable testers, protocol analyzers, multimeters, and software diagnostic tools. Cable testers like TDRs and OTDRs are used to identify cable breaks, while protocol analyzers monitor network activity at different layers. Software tools like ping, tracert, nslookup and dig help diagnose connectivity and DNS issues. The overall goal of troubleshooting is to analyze and resolve a variety of network problems using the appropriate tools.

1. Network
Troubleshooting
Chapter 15

2. Objectives
• Describe appropriate troubleshooting tools
and their functions
• Analyze and discuss the troubleshooting
process
• Tackle a variety of troubleshooting
scenarios

3. • 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

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

5. • 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

6. • 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

7. • 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

8. • 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

9. • 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

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

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

12. • 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