``Multicasting'' is a concept that is defined at a certain protocol level. When discussing multicasting, a clear definition should be given where the copying of the multicasted data is done. For the performance analysis and for implementation purposes, it is important to know how the lowest level of the protocol stack handles the multicast defined at some higher level.
IP multicasting is well defined and implemented in several systems and
platforms. The specification and its implementations are very much
oriented towards multicast capable LANs and in particular, Ethernet.
Currently IP multicasting is only used locally (within a single LAN) and
on the MBone
. The latter
can be considered an experimental use of inter-domain multicasting in
an Internet environment. No Internet-wide deployment of IP multicasting
is available and therefore no experience of the effects of using IP
multicasting in such large-scale systems is available.