1. Check the subrack IDs.
The subrack IDs are configured properly.
2. Replace the network cable.
The problem persists.
3. Disconnect the network cable from the extended subrack, and then remove all boards. Insert the SCC back, and then insert all other boards when the SCC works normally.
All alarms are cleared and the problem is solved.
1. The ID of the original subrack conflicts with that of the extra subrack.2. The network cable connecting the subrack is faulty.