CentreCOM
AT-3624TS/AT-3624TRS
Repeaters
43
On an RJ45 connector, it is important to know where pin 1 is so you can
count your pins correctly. Figure 19 shows the location of pin 1.
Some situations require a DCE-to-DCE connection, for example, when
hubs are cascaded. This can be accomplished with a standard crossover
cable, as illustrated in Figure 20.
In both the crossover and straight-through instances, the wire is twisted
pair. Figure 21 demonstrates usable and unusable cable wire pairings for
the straight-through configuration.
Figure 19: Pin 1 Orientation
on an RJ45
Connector
Pin 1
Figure 20: 10BASE-T UTP
Cabling
Hub-to-Hub or
MAU-to-MAU
(Crossover)
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
TD +
TD -
RD +
Not Used
TD +
TD -
RD +
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
RD -
RD -
RJ45 PIN
RJ45 PIN
Per IEEE 802.3 specifications