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Troubleshooting an Alarm Condition on the ADTRAN DSU IQ

Troubleshooting an Alarm Condition on the ADTRAN DSU IQ

Article ID: 1608

  Troubleshooting an Alarm Condition on the ADTRAN DSU IQ


Troubleshooting an Alarm Condition on the ADTRAN DSU IQ



An alarm condition on the ADTRAN DSU IQ indicates a problem on the frame relay circuit. This condition must be cleared before the application can operate.

Troubleshooting the Alarm Condition

Question: My alarm light is on. What should I do?

Check the physical layer first. Under network port statistics, check the DSU state. There are nine possible states:

56K Normal: Normal Condition for 56k Circuit.
64K Normal: Normal Condition for 64k Circuit.
Open Loop: No sealing current and no RX signal.
OOS/OOF from Net: Out of service code received from the service provider.
No Frame Sync: No frame sync for 64k loop.
DSU In Test: The service provider has placed unit in test.
Scanning: In auto mode searching for the network loop rate.
No RX Signal: Sealing current present, but no RX signal.
Check TELCO: Cable/wiring problem.

If the DSU state is anything other than 56K Normal or 64K Normal, that is the cause of the alarm light. The network port statistics should show the DDS UA time and port UA time incrementing.

Question: What can I do to correct the DSU state?

  • If the DSU IQ is located at an extended demarc, try moving the unit to the demarc in order to eliminate an in-house wiring problem.
  • Try replacing the cable between the DSU IQ and the service provider jack.
  • Connect the DSU IQ to a DDS loopback plug. Set the network clock source to master and the network signaling to none. If the alarm light goes off, the unit is functioning properly.
  • If the DSU state says scanning, try changing the network loop rate from auto to the appropriate rate (56k or 64k).

If none of these efforts eliminate the alarm light, contact the service provider.

Question: Now the DSU state says normal, but the alarm light is still on. What do I do next?

Check layer two. Under network port statistics, check the signaling state. If it says down, this is the cause of the alarm light. Check the following network port statistics: RX Full Status, TX Full Status, RX LI only, and TX LI only. If you see TX, but no RX, the service providerâs frame relay switch is not sending the DSU IQ signaling. Try changing the network signal type. Try all four options (ANSI, ITU-T, LMI, and auto) one at a time. Wait at least a full minute after each change to see if the signal state changes to up. This will allow the DSU IQ and frame relay switch to trade sufficient polls to determine if the circuit is up. If you have tried each signaling type and the signal state remains down, contact the service provider.

If you experience any problems using your ADTRAN product, please contact ADTRAN Technical Support @ 888-423-8726

Version history
Last update:
‎02-28-2012 02:29 PM
Updated by: