Efficient data transfer, optimised resource usage , simplified configuration, optimum bandwidth usage are the main characteristics of Multicast. From the source, if same packet will be sent , with unicast transport you send two copies. This is inefficient for the source PC , for the routers , for the links. Instead, if multicast transport is used, only one copy is sent by the sender.
Receivers join to the multicast group, PIM protocol tells to the source that somebody is interesting with your packet. I recorded a podcast on packet pushers podcast. I shared the link below in this post. My guest is very distinguished speaker, author Beau Williamson. He wrote one of the first book on the subject ‘ Developing IP Multicast Networks ‘. Some of the topics in the podcast :
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