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Monitoring and Testing
Troubleshooting
4-14
The DSU/CSU is designed to provide you with trouble-free service. However,
Table 4-6 gives you some direction if a problem occurs.
For problems other than those listed in the table, please contact your service
representative.
Table 4-6. Troubleshooting (1 of 2)
Symptom
Possible Cause
No power
1. The power module is not
securely attached.
2. The wall receptacle has no
power.
Power-Up
The DSU/CSU has detected an
Self-Test fails
internal hardware failure.
Message LOS at
1. Network cable problem.
NET appears
2. No signal is being transmitted
at the far-end.
3. Facility problem.
Message OOF at
1. Incompatible framing format
between the network and the
Net appears
DSU/CSU.
2. Network cabling problem.
3. Facility problem.
Message
1. Network cable problem.
Yellow at Net
appears
2. Far-end device has lost
framing sync on the line.
3. Facility problem.
Message
1. Upstream device is
transmitting an AIS.
AIS at Net
appears
2. The network is transmitting
an AIS.
Message EER at
Facility problem.
Net appears
March 1999
Solutions
1. Check the power module
attachment.
2. Check the wall receptacle
power by plugging in some
equipment that is known to be
working.
Contact your service
representative.
1. Check that the network cable
is securely attached at both
ends.
2. Check the far-end status.
3. Contact your facility provider.
1. Check that the framing format
for the network interface is
correct.
2. Check that the network cable
is securely attached at both
ends.
3. Contact your facility provider.
1. Check that your network
cable is securely attached at
both ends.
2. Check the status of the
far-end device.
3. Contact your facility provider.
1. Check the status of the
upstream device(s).
2. Contact your facility provider.
Contact your facility provider.
3166-A2-GB20-20
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