1. The DSP is inaccessible because the route to the DSP is unavailable. If all the
links to the DSP are disconnected, the route to the DSP is unavailable.
2. If all the links are distributed on the same subrack and the subrack fails or is
powered off, the links are disconnected.

3. The DSP is inaccessible because of maloperations.

Checklist:

1. According to the onsite checking, the alarm is cleared. The global DSPs are inaccessible for 5 to 6 seconds. Check the links to all office directions by running the DSP N7LNK command. It is found that just several links are disconnected and the time when the links are interrupted is not consistent with the time when the alarm is generated. Check the physical status of the E1 to which the links belong. The status is faulty. Therefore, the links are faulty.
2. Run the DSP N7RT command to check the status of the routing. The routes are normal.
3. Run the LST LOG command to view all operation records on the SAU and check whether the data configuration is modified. The SET OFI command is contained in the log. The command is executed without specifying parameters. According to the log, the command running is successful. The time when the command is executed is
consistent with the time when the faulty alarm is generated. Whether the accessibility of the global DSP is caused by the SET OFI command cannot be confirmed.
4. Run the SET OFI command without specifying parameters on an HLR that is not connected to the network. It is found that the global DSP is inaccessible because of the command running. The DSP is inaccessible for 5 to 6 seconds.
Therefore, you can infer that the global DSP is inaccessible because of the maloperation of running the SET OFI command. After the SET OFI command is executed, the links between the HLR and other offices are disconnected.

This fault is caused by the maloperation of running SET OFI.

very much informative and useful doc. thanks

thanks for the doc

useful information

helpful indeed. thanks

thanks for sharing this nice doc

good findings

well described doc. thanks

good job done

useful document, thanks