CHAPTER B Cables
Twisted-Pair Cable and Pin Assignments
10BASE-T/100BASE-TX PIN ASSIGNMENTS
Use unshielded twisted-pair (UTP) or shielded twisted-pair (STP) cable for RJ-45 connections: 100-ohm Category 3 or better cable for 10 Mbps connections, or 100-ohm Category 5 or better cable for 100 Mbps connections. Also be sure that the length of any twisted-pair connection does not exceed 100 meters (328 feet).
The RJ-45 ports on the switch base unit 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. In straight-through cable, pins 1, 2, 3, and 6, at one end of the cable, are connected straight through to pins 1, 2, 3, and 6 at the other end of the cable. When using any RJ-45 port on this switch, you can use either straight-through or crossover cable.
Table 17: 10/100BASE-TX MDI and MDI-X Port Pinouts
Pin | MDI Signal Name | MDI-X Signal Name |
| | |
1 | Transmit Data plus (TD+) | Receive Data plus (RD+) |
2 | Transmit Data minus (TD-) | Receive Data minus (RD-) |
3 | Receive Data plus (RD+) | Transmit Data plus (TD+) |
6 | Receive Data minus (RD-) | Transmit Data minus (TD-) |
4,5,7,8 | Not used | Not used |
Note:The “+” and “-” signs represent the polarity of the wires that make up each wire pair.
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. (When auto-negotiation is enabled for any RJ-45 port on this switch, you can use either straight-through or crossover cable to connect to any device type.)
You must connect all four wire pairs as shown in the following diagram to support Gigabit Ethernet.
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