eNodeB Nokia down service alarm S1 Interface setup failure

NOKIA SRAN sometimes faced only eNodeB down service but IP from eNodeB to MME is reachable. If you meet this case, we will discuss solution.
Result Ping Test:

Case Study:
1. Check transmission Layer 2 in MW link but in this case MW link doesn't issue because E2E is OK.
2. Check configuration eNB on SRAN if respond correctly to MME IP 
3. Check TAC eNB

In our case eNB down because IP MME and TAC on eNB is wrong with MME.