This chapter described copper cabling test standards, the test parameters required for compliance with those standards, and test configurations.
- Cabling standards continue to evolve. To be certain that the test results obtained certifying a new cable installation are reliable, it is important to keep the cable tester updated with the latest performance specifications.
Testing cable to the requirements of the technology you are deploying is acceptable, but a better practice would be to test to the performance specifications of the installed cable type.
If testing is performed to ensure that a specific technology operates, it is likely to be a less stringent test than if the performance specifications of the installed cable type were tested. Also, knowing that the installed cable performed according to the labeling of the cable instead of a lesser standard would allow a different technology to be used on the same cable plant without requiring a full retest of the cable plant. For example, if a Category 5e cable plant had been tested for use with 100BASE-TX, which requires testing to 80MHz and uses only two pairs, the entire cable plant would have to be retested before 1000BASE-T is deployed. 1000BASE-T requires all four pairs to be tested to 100MHz, plus some additional tests required by Category 5e but not for 100BASE-TX. If the cable plant is certified for Category 5e performance specifications at the time of installation, either Ethernet implementation could be deployed over the cable plant without further testing.
- Understanding what is tested will help you with both installation and testing. Knowing the operational characteristics of cable test parameters is particularly helpful in understanding the purpose for the installation guidelines (such as not untwisting pairs more than absolutely necessary), and also in understanding what to look for when troubleshooting a failed cable performance test.
- Selecting the correct test configuration is an important part of certifying a cable, but abiding by the requirements of the test configuration is just as important. If the channel test configuration is used, but the same patch cables are used to test the entire installation instead of leaving the tested patch cables in place after each test, the testing performed is invalidated. It is important to understand what is required for each test configuration.