CentreCOM 3600 Series Hub/Repeaters
63
UTP MAU-to-MAU,
Hub-to-Hub Wiring
10BASE-T MAU-to-MAU or hub-to-hub wiring generally requires a
crossover cable located somewhere along the UTP cable run. This may
commonly occur at the punch-down block or between the RJ45 wall
receptacle and the workstation. See Figure 8.
MDI/MDI-X
Switch
The AT-3624TR additionally has an MDI/MDI-X pin-out switch that affects
RJ45 Port 1. The RJ45 pin-out straight-through (MDI)/crossover (MDI-X)
switch enables you to use a straight-through cable (see Figure 6) during hub-
to-hub connectivity by simply placing the switch in the MDI position. This
eliminates the need for making or obtaining a crossover cable, as shown in
Figure 8.
The interface type that IEEE specifies as standard for a repeater such as the
AT-3624TR is MDI-X. The straight-through/crossover switch merely
provides convenience to avoid having to obtain an alternate cable in some
applications. If you connect a cable and it does not work, try changing the MDI
switch. The rule of thumb is the total number of crossovers must be odd. You
cannot harm the repeater by having the MDI switch in the wrong position.
Figure 7:
RJ45 Cable
Pin 1
Figure 8:
Hub-to-Hub or
MAU-to-MAU Wiring
Not Used
RD-
Not Used
Not Used
RD+
TD-
TD+
Not Used
Not Used
RD-
Not Used
Not Used
RD+
TD-
TD+
Not Used
RJ 45 Pin
RJ 45 Pin
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Pair twisted as per level 3, 4 or 5 cable
1
1
1
Note