IP layer multicasting is a relatively new feature of the
Internet Protocol. Some
complex constructions had to be invented to make IP multicasting fit in the old
TCP/IP definition (and implementations). The next generation of the
Internet Protocol, IPv6 (or
IPng
, will have full support for
multicasting.
Mapping IP multicasting to LAN multicasting methods involves three separate operations; multicast address resolution to LAN (multicast) addresses, copying/ forwarding of messages and group membership registration.
Before these operations are explained, a definition of what multicasting actually is will be helpful in understanding the special case of IP multicasting implementations.