SFM model
The SFM model is derived from the ASM model. To a multicast source, the two models appear to have the same multicast membership architecture.
The SFM model functionally extends the ASM model. The upper-layer software checks the source address of received multicast packets and permits or denies multicast traffic from specific sources. The receivers obtain the multicast data from only part of the multicast sources. To a receiver, multicast sources are not all valid, but are filtered.