TWISTED-PAIR CABLE AND PIN ASSIGNMENTS
1000BASE-T MDI and MDI-X Port Pinouts
Pin | MDI Signal Name | MDI-X Signal Name |
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1 | Bi-directional Data One Plus (BI_D1+) | Bi-directional Data Two Plus (BI_D2+) |
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2 | Bi-directional Data One Minus (BI_D1-) | Bi-directional Data Two Minus (BI_D2-) |
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3 | Bi-directional Data Two Plus (BI_D2+) | Bi-directional Data One Plus (BI_D1+) |
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4 | Bi-directional Data Three Plus (BI_D3+) | Bi-directional Data Four Plus (BI_D4+) |
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5 | Bi-directional Data Three Minus (BI_D3-) | Bi-directional Data Four Minus (BI_D4-) |
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6 | Bi-directional Data Two Minus (BI_D2-) | Bi-directional Data One Minus (BI_D1-) |
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7 | Bi-directional Data One Plus (BI_D4+) | Bi-directional Data One Plus (BI_D3+) |
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8 | Bi-directional Data Four Minus (BI_D4-) | Bi-directional Data Three Minus (BI_D3-) |
| | |
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: When testing your cable installation, be sure to include all patch cables between switches and end devices.
