Information Transmission In The Broadcast Mode; Information Transmission In The Multicast Mode - H3C S5100-SI Operation Manual

Information Transmission in the Broadcast Mode

When you broadcast traffic, the system transmits information to all users on a network. Any user on the
network can receive the information, no matter if the information is needed or not.
transmission in broadcast mode.
Figure 1-2 Information transmission in the broadcast mode
Assume that Hosts B, D and E need this information. The source server establishes transmission
channels for the devices of these users respectively. As the transmitted traffic over the network is in
direct proportion to the number of users that receive this information, when a large number of users
need the same information, the server must send many packets of information with the same content to
the users. While suitable for networks with small numbers of users, or where information transmitted to
users is significantly different, in other cases this is an inefficient use of the network, and when there is
limited bandwidth, bottlenecks can develop in information transmission. In general, unicast is not good
for the transmission of a great deal of the same information to multiple recipients.

Information Transmission in the Multicast Mode

As described in the previous sections, unicast is suitable for networks with sparsely distributed users,
whereas broadcast is suitable for networks with densely distributed users. When the number of users
requiring information is not certain, unicast and broadcast deliver a low efficiency.
Multicast solves this problem. When some users on a network require specified information, the
multicast information sender (namely, the multicast source) sends the information only once. With
multicast distribution trees established for multicast data packets through multicast routing protocols,
the packets are duplicated and distributed at the nearest nodes, as shown in
1-2
0 shows information
Figure 1-3: