Allied Telesis AT-DMC100/LC, Installation Manual

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Chapter 3: Troubleshooting
54

Try connecting another end node to the twisted-pair port with a
different cable. If the twisted-pair port is able to establish a link,
then the problem is with the cable or the other end-node.

Verify that the twisted-pair cable does not exceed 100 meters (328
feet).

Verify that the end node connected to the media converter is set to
auto-negotiate.

Verify that you are using the appropriate category of twisted-pair
cable: Category 5 or Category 5e.
Note
A 1000Base connection may require 5 to 10 seconds to establish a
link.
Problem 4: The fiber port on the media converter is connected to an end
node, but the fiber port’s LINK/ACT LED is off.
Solutions:
The fiber-optic port on the transceiver is unable to establish a
link to an end node. Try the following:

Verify that the end node connected to the fiber-optic port is
operating properly.

Verify that the fiber-optic cable is securely connected to the port on
the media converter channel and to the port on the remote end-
node.

Verify that the end node connected to the media converter is
operating at the same speed.

Verify that the media converter’s transmitter port (TX) is connected
to the end node’s receiver port (RX) and that the media converter’s
receiver port (RX) is connected to the end node’s transmitter port
(TX).

Verify that the correct type of fiber-optic cabling is being used.

Verify that the wavelength between the media converter and end
node matches, and the media converter fiber port is connected to a
multi-mode (not single-mode) port on the end node.

Verify that the port is connected to the correct fiber-optic cable.
This is to eliminate the possibility that the port is connected to the
wrong remote end-node, such as a powered-off device.

Try connecting another end node to the fiber-optic port using a
different cable. If the port is able to establish a link, then the
problem is with the cable or with the other end node.

If the remote end-node is a management device, use its
management firmware to determine whether its port is enabled.

Test the attenuation on the fiber-optic cable with a fiber-optic tester
to determine whether the optical signal is too weak (sensitivity) or
too strong (maximum input power).