
120 Chapter 2—IPv6 Multicasting
2.4 Multicast Routing Fundamentals
Routing and forwarding in multicast are quite different from unicast. First, since there are
typically multiple recipients of a single original packet, the packet’s delivery path has many
branches, making the entire path a distribution tree. Secondly, unlike unicast routing, the source
address information has an important role in forwarding multicast packets. Additionally, behav-
ior of receiving nodes directly affects routing information via the host-to-router protocol such
as MLD.
This section provides a brief overview of the general background of multicast routing,
and gives an introduction ...