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Chapter 5
Troubleshooting
This section provides a checklist for resolving problems associated with
your hub and cabling. The first rule of troubleshooting is to isolate the
problem. As you experiment, only vary one factor at a time. Substitute
known good equipment to see if the problem persists or is eliminated.
As a preliminary check, perform the following steps
1.
Do not overlook the obvious—check diagnostic LEDs and make
sure the cables and connectors are securely attached.
2.
If there is no power indication, check to be sure the power plug is
properly seated at the repeater and at the AC receptacle.
3.
(UTP models only) If the UTP Link indicator does not illuminate,
make sure the cabling is intact and connected to a functioning port on
the network. Check the cable configuration to make sure the
connectors are wired correctly and a crossover cable is not necessary
(see on for details).
4.
Use only UTP cable designed for use in 10BASE-T applications.
10BASE-T wiring lengths should not exceed 100 meters (328 ft.). The
wiring should be routed away from devices known to emit
electromagnetic interference, such as fluorescent lights, photocopiers,
power transformers and relay equipment.
5.
If the Link indicator illuminates on a 10BASE-T segment, but
data transfer is slow, collision-prone or non-existent, verify that
your UTP cable is of Level 3, 4 or 5. Level 1 and 2 voice-quality cable
will not work properly. If the cable is more or less round in section, you
probably have data-grade cable. If, however, the cable appears flat
(such as “Silver Satin” telephone-type cable), you probably have voice-
grade cable which may cause transmission problems. If it looks like
telephone cable, double check it. Also, if the wire pairing is incorrect,
you may get a Link indication but have high data error rates.
6.
If too many collisions are present on an AUI connection, check
to ensure that the external Ethernet transceiver connected to the AUI
port has the SQE Test (Heartbeat) function disabled. Excessive
network loading can also cause excessive collisions.
7.
If a fault occurs (fault light stays ON), disengage the repeater module
from the backplane, unplug and replug the power cord, and reseat the
module.
