Question: During an eNodeB relocation in a handover procedure without changing the Serving Gateway (SGW)-U, what action does the SGW-C take after the SGW-U switches the S1 path and responds with a successful modification?
Option 1: SGW-C updates the UE's location in the MME.
Option 2: SGW-C sends a release request to the old eNodeB for resource cleanup.
Option 3: SGW-C constructs and sends an "end marker" packet(s) to the SGW-U, which then forwards it to the source eNodeB.
Option 4: SGW-C initiates a new bearer setup with the target eNodeB.
Explanation: This is correct because, according to the described procedure for handling eNodeB relocation during handover without changing the SGW-U, after the path switch is successfully acknowledged by the SGW-U, the SGW-C's next step involves constructing and sending "end marker" packet(s) through the SGW-U to the original eNodeB. This ensures a clean transfer of the session, signaling the end of data transmission on the old path.