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There are no plans for the multicast messaging model in EMS 5.x to support UDP multicast, as supported by TRDP daemons.

PGM can be seen as an evolution of TRDP. The major difference between TRDP (proprietary protocol) and PGM (open protocol) is that the latter may get assistance (such as NAK aggregation, confirmation, etc.) from network elements. You can use the multicast messaging model (introduced in EMS 5.x) even if your network currently does not support multicasting over PGM. However, you may not get assistance from network elements and the resulting advantages thereof.  

This being said, the network elements need to be multicast enabled and you may need root/admin access to start EMS/EMS multicast daemon (PGM opens a raw IP socket). The EMS/EMS multicast daemon releases the root privileges once the raw socket is obtained. As in the TRDP daemon, in the above scenario, if the packets are dropped by subscribers the sender (EMS) may get multiple NAK for the same packet if it was missed by several multicast enabled subscribers.

Are there any plans to support a multicast messaging model in EMS 5.x using UDP (instead of PGM) multicast? Can the multicast messaging model (introduced in EMS 5.x) be used if network elements do not support multicasting over PGM?