S1, S1-U, S1-MME Interface (The EPC/EPS Interface)

The S1-U interface connects the SGW to an eNodeB. The interface is based on the GTPv1-U protocol. The interface delivers payload (user data packet).

The S1-MME interface connects the MME to eNodeBs. The interface is based on SCTP. The interface transports signaling S1-AP (S1 Application Protocol) messages between the MME and eNodeB.

Please refer to The EPS Interface.