Operation Manual – Multicast ProtocolH3C S3610&S5510 Series Ethernet Switches Chapter 5 IGMP Configuration5-5is interested only in the multicast data that Source 1 sends to G but not in the data fromSource 2.Source 2ReceiverHost AHost BHost CPackets (S1,G)Packets (S2,G)Source 1Figure 5-2 Flow paths of source-and-group-specific multicast trafficIn the case of IGMPv1 or IGMPv2, Host B cannot select multicast sources when it joinsmulticast group G. Therefore, multicast streams from both Source 1 and Source 2 willflow to Host B whether it needs them or not.When IGMPv3 is running between the hosts and routers, Host B can explicitly expressits interest in the multicast data Source 1 sends to multicast group G (denoted as (S1,G)), rather than the multicast data Source 2 sends to multicast group G (denoted as (S2,G)). Thus, only multicast data from Source 1 will be delivered to Host B.II. Enhancements in query and report capabilities1) Query message carrying the source addressesIGMPv3 supports not only general queries (feature of IGMPv1) and group-specificqueries (feature of IGMPv2), but also group-and-source-specific queries.z A general query does not carry a group address, nor a source address;z A group-specific query carries a group address, but no source address;z A group-and-source-specific query carries a group address and one or moresource addresses.2) Reports containing multiple group recordsUnlike an IGMPv1 or IGMPv2 report message, an IGMPv3 report message is destinedto 224.0.0.22 and contains one or more group records. Each group record contains amulticast group address and a multicast source address list.Group record types include:z IS_IN: The source filtering mode is Include, namely, the report sender requeststhe multicast data from only the sources defined in the specified multicast source
