2.1.2 Multicast

For multicast messages, SRMP MUST be carried out over [SOAP1.1] and PGM [RFC3208]. Both the sending and the receiving sides MUST provide services that support SOAP (as specified in [SOAP1.1]) over PGM (as specified in [RFC3208]) over IP.<2>

When using PGM as the transport, the sender and receivers need to agree on both the multicast address and the port.