Question: In a telecom network utilizing MBMS, what IP Multicast service model is mandated for use by nodes and routers when distributing MBMS payload from the GGSN/MBMS GW to downstream nodes (eNodeB/RNC)?
Option 1: Source Specific Multicast (SSM) as per RFC 4607 and RFC 4604
Option 2: Any-Source Multicast (ASM) with optional SSM support
Option 3: Dense Mode IP Multicast for efficient resource utilization
Option 4: Sparse Mode IP Multicast for reduced network overhead
Explanation: The correct answer is Source Specific Multicast (SSM) because it ensures efficient and targeted distribution of MBMS payload, reducing unnecessary network traffic by only delivering content to specific, interested receivers. SSM's specificity is crucial for managing multicast groups effectively in telecom backbone networks.