How MMEs communicate to each other, are there some interfaces likes S1/X2 for communication between MMEs?

Question

In case of hub-and-spoke topology, X2 messaging can travel all the way back to an aggregation point, which may be co-located with EPC. In such scenario both X2 and S1 traverses same physical path (a.k.a X2 over S1). Please consider both Intra-MME and Inter-MME handover scenarios. Would X2 based handover in such a case yield advantage over S1 based handover. Thanks.

Answer 1

Yes. S10 is the interface which will be used to communicate Mme with another Mme. And the protocol used is GTPV2C. This interface Is mainly comes into picture during handovers like S1 handover incase of handover is from one Mme pool area to another Mme poolarea. And also comes into picture while TAU, if UE changes from one TA to another TA and the new TA results in a New Mme pool area. In both of these scenarios New Mme will contact old MME for subscriber profile. New MME will detect the Old Mme by using GUTI of UE provided already by old mme.

Answer 2

On behalf of Bart -
Yes there is special MME-to-MME interface, it's called S10 :)