Mdi and mdi-x devices, Table e-1, Ee “mdi and mdi-x devices” o – Nortel Networks 450 User Manual
Page 272
Using the BayStack 450 10/100/1000 Series Switch
E-2
302401-D Rev 00
lists the RJ-45 (8-pin modular) port connector pin assignments.
MDI and MDI-X Devices
Media dependent interface (MDI) is the IEEE standard for the interface to
unshielded twisted pair (UTP) cable.
For two devices to communicate, the transmitter of one device must connect to the
receiver of the other device. The connection is established through a crossover
function, which can be a crossover cable or a port that implements the crossover
function internally.
Ports that implement the crossover function internally are known as MDI-X ports,
where X refers to the crossover function.
The following sections describe the use of straight-through and crossover cables
for connecting MDI and MDI-X devices.
Table E-1.
RJ-45 Port Connector Pin Assignments
Pin
Signal
Description
1
RX+
Receive Data +
2
RX-
Receive Data -
3
TX+
Transmit Data +
4
Not applicable
Not applicable
5
Not applicable
Not applicable
6
TX-
Transmit Data -
7
Not applicable
Not applicable
8
Not applicable
Not applicable
Note:
For the transmitter of one device to connect to the receiver of another
device, the total number of crossovers must always be an odd number.
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