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Maintenance
4-113170-A2-GB20-20 December 1996
Troubleshooting
The E1 DSU/CSU is designed to provide you with
many years of 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
(1 of 2)
Troubleshooting
Symptom
Possible Cause Solutions
No power 1. The power cord is not securely plugged into
the wall receptacle or rear panel connector.
2. The wall receptacle has no power.
1. Check that the power cord is securely
attached at both ends.
2. Check the wall receptacle power by plugging
in some equipment that is known to be
working.
Power-Up
Self-Test fails
The E1 DSU/CSU has detected an internal
hardware failure.
Contact your field service representative.
Message LOS at
Net appears
1. Network cable problem.
2. No signal is being transmitted at the far-end
E1 DSU/CSU.
3. E1 facility problem.
4. The 120 ohm interface is being used and the
RX SHIELD switch is in the EARTH position.
1. Check that the network cable is securely
attached at both ends.
2. Check the far-end E1 DSU/CSU status.
3. Contact your E1 facility provider.
4. Change the RX SHIELD switch to the OPEN
position when using the 120 ohm interface.
Message LOS at
DTE appears
1. DTE Drop/Insert cable problem.
2. No signal being transmitted from the DTE.
1. Check that the DTE Drop/Insert 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 E1 DSU/CSU.
2. Network cabling problem.
3. E1 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 E1 facility provider.
Message OOF at
DTE appears
1. Incompatible framing format between the
Drop/Insert port on the customer premises
equipment and the E1 DSU/CSU.
2. DTE Drop/Insert cabling problem.
1. Check that the framing format for the DTE
Drop/Insert interface is correct.
2. Check that the DTE Drop/Insert cable is
securely attached at both ends.
Message
RAI at Net
appears
1. Network cable problem.
2. Far-end E1 DSU/CSU DTE has detected an
LOS, LOF, AIS, or EER condition.
3. E1 facility problem.
1. Check that your network cable is securely
attached at both ends.
2. Check the status of the far-end device.
3. Contact your E1 facility provider.
Message
RAI at DTE
appears
DTE has detected an LOS, LOF, AIS, or EER
condition.
1. Check the status of the DTE.
2. Check that the DTE Drop/Insert cable is
securely attached at both ends.
Message
AIS at Net
appears
1. Upstream E1 DSU/CSU is transmitting an AIS.
2. The network is transmitting an AIS.
1. Check the status of the upstream E1
DSU/CSU(s).
2. Contact your E1 facility provider.