In the loading state, neighbors exchange LSRs and LSUs to obtain detailed LSAs. If a neighbor is stuck in this state, it indicates that the LSR or LSU exchange fails.

The possible causes are as follows:

1.The neighbor responds with an incorrect packet after receiving an LSR: You can run the display ospf error command to find whether such an error occurs.
2.No sufficient memory is available to process the packet received from the neighbor: You can run the display process memory command to check the process memory.

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