Overview
8

Auto MDI/MDI-X

An RJ-45 twisted pair port on a 10 Mbps or 100 Mbps Ethernet network
device can have one of two possible wiring configurations: MDI or MDI-X. The
RJ-45 port on a PC, router, or bridge is typically wired as MDI, while the
twisted pair port on a bridging converter or hub is usually MDI-X.
To connect two 10 Mbps or 100 Mbps network devices together that have
dissimilar port wiring configurations, such as MDI to MDI-X, you would
usually use a straight-through twisted pair cable. To connect two network
devices that have the same wiring configuration, such as MDI to MDI, you
would usually use a crossover cable.
The AT-FS238a/x and AT-FS238b/x Series Bridging Converters feature
automatic MDI/MDI-X. The RJ-45 port automatically determines the
configuration of the port on the device to which it is connected and then
configures itself appropriately. For example, if a port on a bridging converter
is connected to a port on a bri dge, which is typicall y wired as MDI, the port on
the bridging converter automatically configures itself as MDI-X. This feature
allows you to use either crossover cables or straight-through cable when
connecting a device to the twisted pair port.
Fiber Optic Port
The AT-FS238a/x and AT-FS238b/x Series Bridging Converters have one
100Base-FX fiber optic port. The single-mode fiber optic port features a
simplex SC connecto r.

Port Speed

The fiber optic port is compliant with the 100Base-FX standard and has a
fixed operating speed of 100 Mbps. The end-node connected to the fiber optic
port on the bridging converter must also be able to operate at 100 Mbps. The
AT-FS238a/x and AT-FS238b/x Series Bridging Converters can send and
receive on the two different wavelengths (1310nm and 1550nm). The different
wavelengths used by these bridging converters are as follow:
❑AT-FS238a/x - TX=1310 and RX=1550
❑AT-FS238b/x - TX=1550 and RX=1310
Note
The AT-FS238a/x and AT-FS238b/x Series Bridging Converters are
designed to be used in pairs; therefore, the AT-FS238a/x fiber must be
connected to the A T-FS238b/x fiber only.