Choosing a Multicast IP Address

Question

I find it hard to understand how multicast addresses work.

First, is it true that if I have N clients or peers operating on separate networks, they all subscribe to the same multicast group, and this group allows any source to send messages, these peers / nodes can share data with each other another through this group? (sounds like black magic!)

Secondly, I heard that IANA monitors / regulates multicast addresses. So should you request / ask IANA for a specific multicast address for your project / company? How it works? Am I mistaken? Can you clarify the multicast network for me?

Thank you so much!

Answer 1

First, multicast only works if the routers on the network support it. The IGMP protocol is used for this purpose: http://en.wikipedia.org/wiki/Internet_Group_Management_Protocol . Assuming you have N clients on separate networks connected by multicast-enabled routers, they can send messages to the multicast address, and other peers that subscribe to this multicast address will receive these messages. You can read more on Wikipedia's multicast .

, IEEE IANA, - (IANA). http://www.iana.org/assignments/multicast-addresses/multicast-addresses.xml .