10Base-T/100Base-Tx Pin Assignments; Straight-Through Wiring; Table B-1 10/100Base-Tx Mdi And Mdi-X Port Pinouts - SMC Networks 8708L2 Installation Manual

C
ABLES

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 switch's management port supports 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 the switch's management port, you can use either
straight-through or crossover cable.

Table B-1 10/100BASE-TX MDI and MDI-X Port Pinouts

Pin
1
2
3
6
4,5,7,8
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
these switches, you can use either straight-through or crossover cable to
connect to any device type.)
We recommend connecting all four wire pairs as shown in the following
diagram to allow the same cabling to used for Gigabit Ethernet networks.
B-2
MDI Assignment
Output Transmit Data +
Output Transmit Data -
Input Receive Data +
Input Receive Data -
Not used
MDI-X Assignment
Input Receive Data +
Input Receive Data -
Output Transmit Data +
Output Transmit Data -
Not used