HP MSR2003 Configuration Manual page 69

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
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 23 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. The
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)). It also can explicitly
express that it does not want to receive the multicast data that Source 2 sends to multicast group G
(denoted as (S2, G)). As a result, Host B receives only multicast data from Source 1.
Enhancements in query and report capabilities
Query message carrying the source addresses
•
IGMPv3 is compatible with IGMPv1 and IGMPv2 and supports general queries and group-specific
queries. It also introduces group-and-source-specific queries.
A general query does not carry a group address or a source address.
A group-specific query carries a group address, but no source address.
A group-and-source-specific query carries a group address and one or more source addresses.
• Reports containing multiple group records
Unlike an IGMPv1 or IGMPv2 report message, an IGMPv3 report message is destined to
224.0.0.22 and contains one or more group records. Each group record contains a multicast
group address and a multicast source address list.
Group records include the following categories:
Figure 23, the network comprises two multicast sources, Source 1 (S1) and Source 2 (S2),
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