Maintenance
4-14 3160-A2-GB21-80
March 1999
Troubleshooting

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 3)

Symptom Possible Cause Solutions

No power 1. The power module is not
securely attached.
2. The wall receptacle has no
power.
1. Check the power module
attachment.
2. Check the wall receptacle
power by plugging in some
equipment that is known to be
working.
Power-Up
Self-Test fails The DSU/CSU has detected an
internal hardware failure. Contact your service
representative.
Message LOS at
NET appears 1. Network cable problem.
2. No signal is being transmitted
at the far-end.
3. Facility problem.
1. Check that the network cable
is securely attached at both
ends.
2. Check the far-end status.
3. Contact your facility provider.
Message LOS at
DTE appears 1. DTE Drop/Insert (DSX-1)
cable problem.
2. No signal being transmitted
from the DTE.
1. Check that the DTE
Drop/Insert (DSX-1) cable is
securely attached at both
ends.
2. Check the DTE status.
Message OOF at
Net appears 1. Incompatible framing format
between the network and the
DSU/CSU.
2. Network cabling problem.
3. Facility problem.
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.
Message OOF at
DTE appears 1. Incompatible framing format
between the Drop/Insert port
on the customer premises
equipment and the
DSU/CSU.
2. DTE Drop/Insert (DSX-1)
cabling problem.
1. Check that the framing format
for the DTE Drop/Insert
(DSX-1) interface is correct.
2. Check that the DTE
Drop/Insert (DSX-1) cable is
securely attached at both
ends.