R21xx-HP FlexFabric 11900 IP Multicast Configuration Guide

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local subnet has no member hosts for the group and stops maintaining the memberships for the
group.
IGMPv3 enhancements
IGMPv3 is based on and is compatible with IGMPv1 and IGMPv2. It provides hosts with enhanced
control capabilities and provides enhancements of query and report messages.
Enhancements in control capability of hosts
IGMPv3 introduced two source filtering modes (Include and Exclude). These modes allow a host to join
a designated multicast group and to choose whether to receive or reject multicast data from a designated
multicast source. When a host joins a multicast group, one of the following occurs:
• If the host expects to receive multicast data from specific sources like S1, S2, …, it sends a report
with the Filter-Mode denoted as "Include Sources (S1, S2, …)."
• If the host expects to reject multicast data from specific sources like S1, S2, …, it sends a report with
the Filter-Mode denoted as "Exclude Sources (S1, S2, …)".
As shown in Figure 22,
the network comprises two multicast sources, Source 1 (S1) and Source 2 (S2),
both of which can send multicast data to the multicast group G. Host B is interested in the multicast data
that Source 1 sends to G but not in the data from Source 2.
Figure 22 Flow paths of source-and-group-specific multicast traffic
In IGMPv1 or IGMPv2, Host B cannot select multicast sources when it joins the multicast group G, and
multicast streams from both Source 1 and Source 2 flow to Host B whether or not it needs them.
When IGMPv3 runs between the hosts and routers, Host B can explicitly express that it needs to receive
the multicast data that Source 1 sends to the multicast group G (denoted as (S1, G)), rather than the
multicast data that Source 2 sends to multicast group G (denoted as (S2, G)). Only multicast data from
Source 1 is delivered to Host B.