Cisco Catalyst WS-X3001 Installation And Configuration Manual page 32

ISL Functional Overview and Specifications
Observe the following warnings and notes when cabling a dual-port Fast Ethernet expansion module
with fiber-optic cable.
Warning
Warning
The ports on the module, and the fiber-optic network that it is connected to, use laser light. Do not
stare into a fiber-optic port or into the end of a cable that is connected to a fiber-optic port.
When cabling the Dual Port Fast Ethernet modules, the polarity of the fiber cable connectors must
be "crossed-over." The TX (transmit) connector of one device goes to the RX (receive) connector of
the other device. Check the polarity of each side of the fiber-optic cable. Use one side of the
fiber-optic cable to connect from the transmit (Tx) side of a dual-port Fast Ethernet module to the
receive (Rx) side of another device. Use the other side of the cable to connect the receive side of the
dual-port Fast Ethernet module to the transmit side of the other device.
Note
The two fibers are identical, but for determining polarity there are several different conventions to
enable you to tell the fibers apart. There may be a difference in color, or on some fiber-optic cables,
only one of the fibers has lettering imprinted on its insulating sheath. Use the markings as polarity
indicators.
Checking the Installation/Troubleshooting
When the link is established, the LINK LED is on. If the LED is not on, try the following tests:
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If the above tests do not correct the problem, contact Cisco support.
If, after installation, there is poor system performance or the Dual Port Fast Ethernet module does
not work at all, remove the module and check for any damage or bent connector pins. You may need
a bright light to see inside the expansion module slot to check for bent pins. If you cannot find an
immediate cause for the problem, contact Cisco support.
32 Catalyst Matrix and Expansion Module Installation and Configuration Guide
Laser radiation is present when the system is open.
Do not stare into the laser beam.
Fiber-optic cables have two separate fibers for delivery of data to and from the transceiver.
Check the cable connections.
Try swapping the TX/RX fiber connectors at one end.
Verify that you are using the correct type of cable
Test whether the cable is bad by trying a different one.
Check the power-up diagnostics to see if any problems were reported.