Description
6
MDI/MDI-X Switch
The Medium Dependent Interface (MDI/MDI-X) is an internal signal
crossover that allows you to use a 10BaseT port to link one hub to another, or
to connect a hub to hub using the network port. This type of connection
requires the signal to “crossover” so that the TX pin at one end connects to the
RX pin at the other end.
The 10Base-T RJ-45 ports generally are used for network connections between
the hub and Network Interface Card (NIC). This connection requires a
standard straight-through cable which has a pin at one end that connects to a
pin with the same number at the other end.
However, you may want to use one of the 10Base-T ports to link one hub to
another. You also can connect a hub to a hub using the network backbone port.
This connection requires the signal crossover so that the TX pin at one end
connects to the RX pin at the other end.
When connecting two hubs via the 10Base-T port, or when when connecting
two hubs via the network port, you must use the one of the following:
❑
a special crossover cable, available commercially at most electronic
outlets
❑
a built-in method for internally crossing the signal over, before it is
transmitted through the cable.
ATI has incorporated the latter technique into the AT-3012SL, 3016SL,
3024SL models. The MDI/MDI-X switch at the far left of the switch’s front
panel converts RJ-45 Port 1 from a normal network connector into an
internally crossed-over port for hub-to-hub connection:
❑
The default setting for the switch is MDI-X (standard RJ-45 port) (see
Figure 7).
❑
If you want to use Port 1 to connect two hubs, you must set the switch
on only one of the hubs to the MDI position.
By using the MDI/MDI-X switch, you can connect two hubs through standard
straight-through cable. The switch affects Port 1 only; you can continue to use
all the other 10Base-T ports for network connections through straight-
through cable, no matter how you set the MDI/MDI-X switch.
