MS_APS_INDI_EX and APS_INDI alarms were observing continuously. After the customer's complaint, i checked the parameters and configuration in detail. There was a Linear MS made on which alarm occured.
I simply changed the option from Non-Revertive to Revertive and also from Single-Ended to Dual-Ended so that if in future the problem occurs at any end, it simply switch itself accordingly.
I checked the configuration in detail and the cause was found. Linear MS was made and Non-Revertive option was selected. Due to this, after the degradation, the switching occured and was not reverted to the orignal.
If such problem occurs, check the following
1) Revertive or Non-Revertive
2) Parameters of alarms (first parameter shows the protection scheme, Linear MS or Ring MS)