Multicast versus Unicast and broadcast: http://fr.wikipedia.org/wiki/Multicast

==> RFC: IETF IP multicast :https://tools.ietf.org/html/rfc5771

Understanding the P2P (French):

the Peer to Peer is not a “protocol” it is a software solution (based on client/server mechanism and TCP/IP protocol)

http://www.generation-nt.com/peer-to-peer-peer2peer-p2p-partage-fichiers-internet-article-40573-1.html