CHAPTER B Cables
Twisted-Pair Cable and Pin Assignments
1000BASE-T PIN ASSIGNMENTS
All 1000BASE-T ports support automatic MDI/MDI-X operation, so you can use straight-through cables for all network connections to PCs or servers, or to other switches or hubs.
The table below shows the 1000BASE-T MDI and MDI-X port pinouts. These ports require that all four pairs of wires be connected. Note that for 1000BASE-T operation, all four pairs of wires are used for both transmit and receive.
Use 100-ohm Category 5, 5e or 6 unshielded twisted-pair (UTP) or shielded twisted-pair (STP) cable for 1000BASE-T connections. Also be sure that the length of any twisted-pair connection does not exceed 100 meters (328 feet).
Table 18: 1000BASE-T MDI and MDI-X Port Pinouts
Pin | MDI Signal Name | MDI-X Signal Name |
| | |
1 | Bi-directional Pair A Plus (BI_DA+) | Bi-directional Pair B Plus (BI_DB+) |
2 | Bi-directional Pair A Minus (BI_DA-) | Bi-directional Pair B Minus (BI_DB-) |
3 | Bi-directional Pair B Plus (BI_DB+) | Bi-directional Pair A Plus (BI_DA+) |
4 | Bi-directional Pair C Plus (BI_DC+) | Bi-directional Pair D Plus (BI_DD+) |
5 | Bi-directional Pair C Minus (BI_DC-) | Bi-directional Pair D Minus (BI_DD-) |
6 | Bi-directional Pair B Minus (BI_DB-) | Bi-directional Pair A Minus (BI_DA-) |
7 | Bi-directional Pair D Plus (BI_DD+) | Bi-directional Pair C Plus (BI_DC+) |
8 | Bi-directional Pair D Minus (BI_DD-) | Bi-directional Pair C Minus (BI_DC-) |
| | |
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.
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