Foundry Networks OSI - Manual (Page 47)

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February 2003 © 2003 Foundry Networks, Inc. B-5
1000BASE-T Cable Requirements
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.