Question: In a Home NodeB setup, how does a Local Gateway (L-GW) determine which multicast IP datagrams to forward between the UE and the network accessed by LIPA?
Option 1: Based on multicast group membership report messages received from the network or the UE, adhering to standards like RFC 3376 or RFC 3810.
Option 2: By analyzing the destination port numbers of incoming IP datagrams.
Option 3: Through static configuration of multicast group addresses on the L-GW.
Option 4: Using a proprietary protocol for multicast management.
Explanation: The correct answer is Option 1 because, according to the specifications, an L-GW relies on multicast group membership report messages (following standards such as RFC 3376 or RFC 3810) sent by either the network accessed by LIPA or the UE itself. This mechanism allows the L-GW to intelligently forward relevant multicast IP datagrams in both directions, ensuring efficient use of resources and delivery of desired content to UEs employing Local IP Access (LIPA).