Source-Specific Multicast (SSM)

If we consider inter-domain multicast service, ...
One-to-many or few-to-many communication model is feasible
Each source address can be recognized beforehand
If each source address is known by each multicast listener, ...
SPT can be constructed directly
          → No need to create and maintain RPT
          → RP and MSDP are not required by routing
             protocols
          → ASM's complexity and scalability problems are
             eliminated

Source-Specific Multicast (SSM) is the solution