H3C S7500E Series Operation Manual page 624

Operation Manual – Multicast
H3C S7500E Series Ethernet Switches
Figure 1-2 Broadcast transmission
Assume that only Hosts B, D, and E need the information. If the information source
broadcasts the information, Hosts A and C also receive it. In addition to information
security issues, this also causes traffic flooding on the same network.
Therefore, broadcast is disadvantageous in transmitting data to specific hosts;
moreover, broadcast transmission is a significant usage of network resources.
III. Multicast
As discussed above, the unicast and broadcast techniques are unable to provide
point-to-multipoint data transmissions with the minimum network consumption.
The multicast technique has solved this problem. When some hosts on the network
need multicast information, the multicast source (Source in the figure) sends only one
copy of the information. Multicast distribution threes are built for the multicast packets
through multicast routing protocols, and the packets are replicated only on nodes
where the trees branch, as shown in Figure 1-3:
1-3
Chapter 1 Multicast Overview