Description: Indicates the alarm reason as below: 1. Bridge type mismatch, one side is 1:1 (Selector Bridge) protection, the other side is 1+1 (Permanent Bridge) protection; 2. Channel type mismatch, one side has APS channel, the other side has no APS channel; 3. Switching type mismatch, one side is bidirectional switching, the other side is unidirectional switching; 4. Operation type mismatch, one side is revertive operation, the other side is non-revertive operation; 5. Traffic request mismatch, one side selects working connection, the other side selects protection connection;