Port and Cable Assignments
Port and Cable Assignments
RJ-45 Port Description
RJ-45 station ports (MDI-X) can be attached to any devices that use a standard network interface (e.g., a workstation, server, bridge or
router). RJ-45 daisy-chain ports (MDI) can be cascaded to a station port on similar
networking devices (e.g., another switch or hub). Use unshielded twisted-pair (UTP) or shielded twisted-pair (STP) cable for RJ-45 connections: 100-ohm Category 3, 4 or 5 cable for 10 Mbps connections or 100-ohm Category 5 cable for 100 Mbps connections. Also be sure that the length of any twisted-pair connection does not exceed 100 meters (328 feet).
Pin | MDI-X Signal Name | MDI Signal Name |
1 | Receive Data plus (RD+) | Transmit Data plus (TD+) |
2 | Receive Data minus (RD-) | Transmit Data minus (TD-) |
3 | Transmit Data plus (TD+) | Receive Data plus (RD+) |
6 | Transmit Data minus (TD-) | Receive Data minus (RD-) |
4,5,7,8 | Not Used | Not Used |
Straight-Through Wiring
If the twisted-pair cable is to join two ports and only one of the ports has an internal crossover (MDI-X), the two pairs of wires must be straight-through.
| | Straight-Through RJ-45 Pin Assignments |
End 1 | End 2 |
1 | (RD+) | 1 | (TD+) |
2 | (RD-) | 2 | (TD-) |
3 | (TD+) | 3 | (RD+) |
6 | (TD-) | 6 | (RD-) |
Crossover Wiring
If the twisted-pair cable is to join two ports and either both ports are labeled with an “X” (MDI-X) or neither port is labeled with an “X” (MDI), a crossover must be implemented in the wiring.
| | Crossover RJ-45 Pin Assignments |
End 1 | End 2 |
1 | (TD+) | 3 | (RD+) |
2 | (TD-) | 6 | (RD-) |
3 | (RD+) | 1 | (TD+) |
6 | (RD-) | 2 | (TD-) |
