Foundry Networks OSI Manuale Utente

February 2003

© 2003 Foundry Networks, Inc.

B-5

All Category 5 UTP cables that are used for 100BASE-TX connections 
should also work for 1000BASE-T, providing that all four wire pairs are 
connected. However, it is recommended that for all critical connections, or 
any new cable installations, Category 5e (enhanced Category 5) or 6 cable 
should be used. The Category 5e and 6 specifications include test 
parameters that are only recommendations for Category 5. Therefore, the 
first step in preparing existing Category 5 cabling for running 
1000BASE-T is a simple test of the cable installation to be sure that it 
complies with the IEEE 802.3ab standards.

Cable Testing for Existing Category 5 Cable
Installed Category 5 cabling must pass tests for Attenuation, Near-End 
Crosstalk (NEXT), and Far-End Crosstalk (FEXT). This cable testing 
information is specified in the ANSI/TIA/EIA-TSB-67 standard. 
Additionally, cables must also pass test parameters for Return Loss and 
Equal-Level Far-End Crosstalk (ELFEXT). These tests are specified in the 
ANSI/TIA/EIA-TSB-95 Bulletin, “The Additional Transmission 
Performance Guidelines for 100 Ohm 4-Pair Category 5 Cabling.”

Note that when testing your cable installation, be sure to include all patch 
cables between switches and end devices.

Adjusting Existing Category 5 Cabling to Run 1000BASE-T
If your existing Category 5 installation does not meet one of the test 
parameters for 1000BASE-T, there are basically three measures that can be 
applied to try and correct the problem:

1. Replace any Category 5 patch cables with high-performance Category 

6 cables.

2. Reduce the number of connectors used in the link.

3. Reconnect some of the connectors in the link.