Appendix B Recommended Tools and Test Equipment

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

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:

PCs

Printers

Modems

CSU/DSUs

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:

Isolate problems

Identify bit patterns

Ensure that the correct cabling is installed

These devices cannot test media signals such as Ethernet, Token Ring, or FDDI.

Testing with Network Monitors

Use network monitors to:

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

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:

Create profiles of LAN traffic

Locate traffic overloads

Plan for network expansion

Detect intruders

Establish baseline performance

Distribute traffic more efficiently

Cisco uBR10012 Universal Broadband Router Troubleshooting Guide

 

OL-1237-01

B-3

 

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Cisco Systems UBR10012 manual Testing with Network Monitors, Testing with Breakout Boxes, Fox Boxes, and BERTs/BLERTs