Chapter 37 IGMP
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on a particular network. This in turn helps reduce the amount of multicast traffic
going through the multicast router.
Figure 173 IGMP Version 2 Example
IGMP version 3 allows a multicast host to join a multicast group and specify from
which source (multicast server) it wants to receive multicast packets.
Alternatively, a multicast host can specify from which multicast servers it does not
want to receive multicast packets. In the following figure multicast server X (IP
address 10.1.1.1) and multicast server Z (IP address 13.2.2.2) both send
multicast traffic to the same multicast group identified by the multicast IP address
225.1.1.1. In IGMP version 3 multicast host A can join multicast group
225.1.1.1 and specify that it only wants to receive multicast packets from server
X.
Figure 174 IGMP Version 3 Example
37.2 Port-based IGMP
The Switch sends IGMP Query packets to all ports. The Switch then listens for
IGMP Report packets, and it records which port the messages came from. It then
delivers multicast traffic to only those ports from which it received a request to
join a multicast group.
Join: 225.1.1.1
Include: 10.1.1.1
Group: 225.1.1.1
Server: 13.2.2.2
Group: 225.1.1.1
Server: 10.1.1.1
A
X
Z
