Accton Technology VM2548 - Manual (Page 47)

Twisted-Pair Cable and Pin Assignments
B-3
1000BASE-T Pin Assignments
1000BASE-T ports switch 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 or 5e 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).
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) cable should be used. The Category 5e
specification includes 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.
Pin MDI Signal Name MDI-X Signal Name
1 Transmit Data plus (TD1+) Transmit Data plus (TD2 +)
2 Receive Data minus (RD1-) Receive Data minus (RD2-)
3 Transmit Data plus (TD2+) Transmit Data plus (TD1+)
4 Transmit Data plus (TD3+) Transmit Data plus (TD4+)
5 Receive Data minus (RD3-) Receive Data minus (RD4-)
6 Receive Data minus (RD2-) Receive Data minus (RD1-)
7 Transmit Data plus (TD4+) Transmit Data plus (TD3+)
8 Receive Data minus (RD4-) Receive Data minus (RD3-)