Hi Alok,
You entered your question in the ServiceGrid Support Community.
We are part of software enabled services and have nothing to do with ipv4 or ipv6
To your question about a definition:
A multicast address is a logical identifier for a group of hosts in a computer network, that are available to process datagrams or frames intended to be multicast for a designated network service. Multicast addressing can be used in the Link Layer (Layer 2 in the OSI model), such as Ethernet multicast, and at the Internet Layer (Layer 3 for OSI) for Internet Protocol Version 4 (IPv4) or Version 6 (IPv6) multicast.
best regards
Patrick
