Networking / Beginners

Getting the scoop on loops

There are two varieties of testing loops in the world of telecom: soft loops and hard loops. CSUs and NIUs generate soft loops, which use software to bounce the signaling on a circuit back to its point of origin. You create hard loops by physically wiring together the transmit and receive lines on a circuit. You typically place a hard loop in a circuit by using a loopback plug, but both loops perform the same function.

If you can't loop the NIU

If you can't loop the NIU, there is a problem in the local loop, or possibly within your long-distance carrier's network. The only way to isolate the issue is to continue working back on the circuit towards the CFA point until you find a good section that doesn't have errors. In this case, proceed straight to "Step 5: Looping the CFA point" for additional troubleshooting.

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In this tutorial:

  1. Troubleshooting Your Dedicated Circuits
  2. Identifying the Level of Your Problem
  3. Identifying circuit variables in circuits that are DS-3 or larger
  4. Identifying DS-1-level circuit variables
  5. Identifying DS-0 or individual channel issues
  6. Categorizing the Nature of Your Problem
  7. Understanding dedicated call quality issues
  8. Understanding circuit failure issues
  9. Opening a Trouble Ticket for Your Dedicated Circuit
  10. Letting your channels be your guide
  11. Remembering the first rule of troubleshooting
  12. Remote made busy: RMB
  13. Installation made busy: IMB
  14. Avoiding permanent IMB status
  15. Managing Your Dedicated Trouble Ticket
  16. Getting the Basics of Dedicated Outbound Troubleshooting
  17. Step 1: Rebooting your hardware
  18. Understanding your trouble ticket options
  19. Step 2: Intrusively testing: Looping the CSU
  20. If looping the CSU fails
  21. Using a T-1 test set
  22. Step 3: Looping the NIU
  23. Getting the scoop on loops
  24. Step 4: Looping to your T-1 jack
  25. If you can't loop the T-1 jack
  26. Step 5: Looping the CFA point
  27. Following a Dedicated Troubleshooting Shortcut
  28. Validating the Circuit You Are Testing
  29. The Basics of Dedicated Toll-Free Troubleshooting
  30. Step 1: Identifying a provisioning issue
  31. Step 2: Redialing your dedicated toll-free number
  32. Step 3: Validating your dedicated RespOrg
  33. Step 4: Validating the DNIS configuration
  34. Step 5: Head-to-head dedicated toll-free testing