Multicast
"Other advantages of IPv6 are said to be support for multicast transmissions, allowing bandwidth-intensive traffic like multimedia streams to be sent to multiple destinations simultaneously rather than as multiple individual connections, thus saving on network bandwidth.”
Multicast is also available when using ipv4, see RFC 1112. The subtlety is that there are no broadcasts in ipv6. Traditional broadcast functions from ipv4 such as Address Resolution Protocol (ARP) have equivalence in ipv6, using local pre-defined multicast groups. In the case of ARP that would be Neighbor Discovery Protocol (NDP). NDP is more efficient than ARP. For example, there is a multicast group for routers on a segment. To learn a router’s MAC address, a host need only send a query to that group. As most nodes will not subscribe to it, they will not receive traffic in which they have no interest.
Biting the hand that feeds IT
