METRObility Optical Systems 3508-11 - Manual (Page 12)

12 User Guide
Troubleshooting
Cabling Problems
Improper cabling is the primary cause of most network problems, particularly for
100Base-TX and 100Base-FX networks. Use only the specified twisted-pair or fiber
optic cables to avoid most cabling problems.
• Flat telephone extension cables, or Category 3 wires, are not the same as
Category 5 twisted-pair cables and will not function on Fast Ethernet networks.
• There is a wiring problem if the Link/Act LED does not illuminate when the
RJ-45 plug from a workstation is inserted into the port jack. Correct the
break in the cable or replace the cable before proceeding.
• If a workstation (workstation A) does not function while workstations con-
nected to other ports on the CenturySwitch operate normally, remove an RJ-
45 plug from a functioning port with a functioning workstation (workstation
B) and insert it into the suspect port. If workstation B still works, the prob-
lem may be in workstation A or in the wiring. However, if workstation B
does not work, the CenturySwitch may have a defective port. Even if you
suspect a defective port, continue testing. Improperly wired workstations
may appear functional, especially if they are located near the switch. Some-
times a port connected to an improperly wired workstation functions mar-
ginally while another port does not work at all.
• Once you have established that the CenturySwitch is working properly, check all
wiring between it and the malfunctioning workstation. Be sure that the transmit
(TX) and receive (RX) cables are not crossed. The transmit cable from the worksta-
tion should connect to the receive connector of the switch and the transmit cable
from the switch should connect to the receive connector of the workstation.
• Use a continuity checker to ensure that wires do not have any breaks. By
shorting together the two wires at the end of a pair, you can use the continuity
checker at the other end. Also check that there are no shorts between wires.
Workstation Problems
Most non-cabling problems result from improper configuration of the network
interface card (NIC) and its corresponding driver. Observe the following points:
• Like other add-on cards in the workstation or server, the NIC must have a
unique memory address, I/O address and interrupt. The settings on a
particular card must not conflict with the settings on any other card in the
same station. Refer to the user’s manuals of your NIC, computer and
network operating system to determine the proper configuration.