L.E-RAB.FailEst.MME...what could be the possible reason for that?

L.E-RAB.FailEst.MME what could be the possible reason for that.

1.Transport layer and radio network layer problems.
2.No resources available at enodeB(Congestion)
3.N o response from the UE.
4.Faults on the MME side
5.Security mode configuration failure

These are the main reasons…for RAB failures…4&5 both are main reasons

Thanks

Your always welcome

L.E-RAB.FailEst.MME appears when the number of E-RAB setup failures triggered by the MME. You should optimize the MME timers or raise this issue with core team