Tech-X Flex™ Base Unit User Guide Issue 1
5: IP and Video Testing 5-25
Intro
Wi-Fi
10/100
System
IP/Video
Specs
About IP multicast
IP multicast is a set of protocols that allows a single IP packet to be sent to multiple hosts (that is, “group
members”) without the need to send multiple redundant copies of the same packet from the source. It
serves to alleviate network congestion when multiple hosts need to receive the same traffic, such as the
case where multiple IPTV subscribers are watching the same channel and each will ultimately receive
the exact same data payload.
Consider the following diagram, which represents a small network without multicasting:
Figure 5-7 Hypothetical network without group multicasting
In the previous figure, three subscribers are watching the same channel. The shaded packets represent
the unicast IP streams required to deliver the service. The IP payload in each stream, however, is exactly
the same, resulting in a redundancy that creates congestion and scalability issues.
Alternatively, consider the following figure, which illustrates group multicasting:
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