After analysis i found that protocol was unstarted in Protection Group. I tried to start that protocol from T2000, but it failed to start the protocol. I deleted that ring from NM layer and then created again, but still protocol was unstarted for this particular NE. Protocol of other NEs in this ring were started and normal.
After anlysed the cause deeply, we found the issue was caused by the inconsistent software. When the slave XCS board which is used the lower version than that of working board, it will make the data synchronization from the working board automatically in case of hard reset or power on. But the slave XCS board which is used the later version than that of working board will not make the activity in that case.
Because the vesions between the active board and the standby board are different and the format of files partition are also different, so the data synchronization will be out-of-order and leads to the abnormal state of MSP.