Testing With Breakout Boxes, Fox Boxes, And Berts/Blerts; Testing With Network Monitors; Testing With Network Analyzers - Cisco 10000 Series Troubleshooting Manual

Appendix B Recommended Tools and Test Equipment

Testing with Breakout Boxes, Fox Boxes, and BERTs/BLERTs

Use breakout boxes, fox boxes, and bit/block error rate testers (BERTs/BLERTs) to measure the digital
signals present at:
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These devices can monitor data line conditions, analyze and trap data, and diagnose problems common
to data communication systems. Traffic from data terminal equipment (DTE) through data
communications equipment (DCE) can be examined to:
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These devices cannot test media signals such as Ethernet, Token Ring, or FDDI.

Testing with Network Monitors

Use network monitors to:
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Network monitors do not decode the contents of frames. Monitors are useful for baselining, in which the
activity on a network is sampled over a period of time to establish a normal performance profile, or
baseline.
Monitors collect information such as packet sizes, the number of packets, error packets, overall usage
of a connection, the number of hosts and their MAC addresses, and details about communications
between hosts and other devices. This data can be used to:
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Testing with Network Analyzers

Use network analyzers (also called protocol analyzers) to decode protocol layers in a recorded frame and
present the layers as readable abbreviations or summaries, detailing which layer is involved (physical,
data link, and so forth) and the function each byte or byte content serves.
OL-0439-02
PCs
Printers
Modems
CSU/DSUs
Isolate problems
Identify bit patterns
Ensure that the correct cabling is installed
Track packets crossing a network
Provide an accurate picture of network activity at any moment
Provide a historical record of network activity over a period of time
Create profiles of LAN traffic
Locate traffic overloads
Plan for network expansion
Detect intruders
Establish baseline performance
Distribute traffic more efficiently
Testing with Breakout Boxes, Fox Boxes, and BERTs/BLERTs
Cisco 10000 Series Router Troubleshooting Guide
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