Multicast Overview; Introduction To Multicast; Information Transmission Techniques - HP 5920 series Configuration Manual

Multicast overview

Introduction to multicast

As a technique that coexists with unicast and broadcast, the multicast technique effectively addresses the
issue of point-to-multipoint data transmission. By enabling high-efficiency point-to-multipoint data
transmission over a network, multicast greatly saves network bandwidth and reduces network load.
By using multicast technology, a network operator can easily provide new value-added services, such as
live webcasting, web TV, distance learning, telemedicine, web radio, real-time video conferencing, and
other bandwidth-critical and time-critical information services.

Information transmission techniques

The information transmission techniques include unicast, broadcast, and multicast.
Unicast
In unicast transmission, the information source must send a separate copy of information to each host that
needs the information.
Figure 1 Unicast transmission
Source
In Figure 1, assume that Host B, Host D and Host E need the information. A separate transmission channel
must be established from the information source to each of these hosts.
In unicast transmission, the traffic transmitted over the network is proportional to the number of hosts that
need the information. If a large number of hosts need the information, the information source must send
a separate copy of the same information to each of these hosts. Sending many copies can place a
tremendous pressure on the information source and the network bandwidth.
IP network
Packets for Host B
Packets for Host D
Packets for Host E
Host A
Receiver
Host B
Host C
Receiver
Host D
Receiver
Host E
1