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Chapter 3: Troubleshooting
48
cable: Category 3 or better for 10 Mbps operation and Category 5
and Category 5E for 100 and 1000 Mbps operation.
Note
A 1000Base connection may require five to ten seconds to establish
a link.
Problem 3: The LINK/ACT LED for an SFP transceiver is off.
Solutions: The fiber optic port on the transceiver is unable to establish a
link to a network device. Try the following:
Verify that the 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 media converter channel and to the port on the remote network
device.
Check that the SFP module is fully inserted in the slot.
Verify that the operating specifications of the fiber optic ports on
the SFP transceiver and the remote network device are
compatible.
Verify that the correct type of fiber optic cabling is being used.
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 network device, such as a powered off device.
Try connecting another network device 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 network device.
Use the switch’s management software to verify that the port is
enabled.
If the remote network device 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).
Problem 4: Network performance between a twisted pair port on the switch
and a network device is slow.
Solution: There might be a duplex mode mismatch between the port and
the network device. This occurs when a twisted pair port using Auto-
Negotiation is connected to a device with a fixed duplex mode of full
duplex. If this is the cause of the problem, adjust the duplex mode of the
port on the network device or on the switch so that both ports are using the
same duplex mode.