Question: Which entities terminate the X2 Application Protocol (X2AP) in an Evolved Universal Terrestrial Radio Access Network (E-UTRAN)?
Option 1: User Equipment (UE) and Serving Gateway (S-GW)
Option 2: Mobility Management Entity (MME) and Home Subscriber Server (HSS)
Option 3: eNodeBs (eNBs) interconnected via the X2 interface
Option 4: Serving Gateway (S-GW) and Packet Data Network Gateway (P-GW)
Explanation: In E-UTRAN, the X2 interface is used for direct communication between neighboring eNodeBs (eNBs), facilitating functions like load management and handover. The X2 Application Protocol (X2AP) is specifically designed to manage signaling across this interface. Therefore, it logically terminates at the two eNBs that are interconnected via the X2 interface, enabling them to exchange necessary information for efficient network operation.