Straight-through wiring, Crossover wiring – MRV Communications MR2228-S2C User Manual

Page 34

Advertising
background image

30

Table B-1. 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.)

Crossover Wiring

If the twisted-pair cable is to join two ports and 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. (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.)

Advertising