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OSN3500 Setting the PDH service board loopback operation causes service interruption. If the channel used by other services configured by the upstream network element and the channel used by this network element to report alarms are the same VC4 channel, the upstream network element cannot use the loopback method. Loopback is used for fault localization. The outer loopback can be used to test whether the interface module of the veneer and the external cable are normal, and the inner loopback can be used to test whether the cross-connection unit and the service path of the equipment are normal. This task describes how to perform a loopback operation for a PDH electrical interface board.
Prerequisites
The user has the network administrator privilege of "Network Element and Network Operator" or higher.
Impact on the System
A loopback operation reverses the downstream AIS signal. In an unprotected state, loopback may cause service interruption.
The loopback operation can only be used for fault localization, and the loopback setting for that port must be cleared after fault localization.
Tools, Instruments, and Materials
U2000
Background
The device supports PDH electrical interface board external loopback and internal loopback.
| Loopback point | Explanation | Legend |
|---|---|---|
| PDH electrical interface board outer loopback | The external loopback does not change the signal structure. Inside the PDH electrical interface board, the signal from the receive port is looped back directly to the corresponding transmit port before signal processing. It can be used to determine whether the PDH interface and the fiber cable connecting to the PDH single board are normal. |
|
| Internal loopback within the PDH board | The internal loopback has been signalized within the local device. Inside the PDH electrical interface board, signals from the cross-connection unit are looped back to the cross-connection unit after signal processing. It can be used to determine whether the PDH board service processing module and the cross-over board are normal. |
|
Operation Procedure
- Double-click the Main Topology icon in the Workbench view to enter the Main Topology diagram.
- On the main topology map, select the network element that needs to be looped back. Right-click and select "Network Element Manager".
- Select the electrical interface board that needs to be looped back, and select "Configuration > PDH Interface" in the Function Tree.
- Select "By Function" and select "Branch Loopback" from the drop-down menu.
- Select the port to be looped back and choose "Inner Loopback" or "Outer Loopback" from the drop-down menu in the corresponding right column.
- Click "Apply" and the "Confirm" dialog box will pop up, click "OK". The "Prompt" dialog box pops up, click "OK".
- The "Result" dialog box pops up, click "Close".
- Optional: Undo Loopback. Set the loopback method to "No Loopback".
The technical information and SDH equipment troubleshooting procedures in this chapter are provided by Shenzhen Optical Transmission Network Technology Company Limited ( www.opticaltrans.com), please retain them! Huawei SDH Optical Transmission Equipment,SDH Transmission Equipment Sales
