Allied Telesis x330 Series Installation Manual page 114

Chapter 10: Troubleshooting
114
Verify that you are using the appropriate category of cable. Cable

requirements are listed in Table 1 on page 23 and Table 2 on
page 25.
Verify that the port is connected to the correct cable.

Note
Copper ports may require up to five to ten seconds to establish links
to network devices.
Problem 3: The link/activity LED for an SFP or SFP+ transceiver is off.
Solutions: The fiber optic port on the transceiver has not established a
link to the remote network device. Try the following:
Verify that the remote network device connected to the fiber optic

port is operating properly.
Verify that the fiber optic cable is securely connected to the port on

the transceiver and to the port on the remote network device.
Check that the transceiver is fully inserted into the port in the

switch.
Verify that the operating specifications of the fiber optic ports on

the transceiver and remote network device are compatible by
referring to their documentation.
Verify that the correct type of fiber optic cabling is being used.

Verify that the port is connected to the correct fiber optic cable.

Try connecting another network device to the fiber optic port using

a different cable. If the port can establish a link, then the problem is
with the cable or remote network device.
Use the switch's management software to verify that the port is

enabled.
If the remote network device is a managed device, use its

management firmware to determine whether its port is enabled.
If the problem is with two BiDi (bi-directional) transceivers, refer to

their data sheets to confirm that their transmission and reception
frequencies are opposite each other. For example, a BiDi
transceiver that transmits and receives at 1310nm and 1550nm,
respectively, has to be connected to a transceiver that transmits
and receives at 1550nm and 1310nm, respectively. Two BiDi
transceivers that transmit and receive at the same frequencies will
not establish a link.
Test the attenuation on both directions 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).