Enhancements In Igmpv3 - HP 4800G Series Configuration Manual

4) If the querier receives a membership report for the group within the maximum response time, it will
maintain the memberships of the group; otherwise, the querier will assume that no hosts on the
subnet are still interested in multicast traffic to that group and will stop maintaining the
memberships of the group.

Enhancements in IGMPv3

Built upon and being compatible with IGMPv1 and IGMPv2, IGMPv3 provides hosts with enhanced
control capabilities and provides enhancements of query and report messages.
Enhancements in control capability of hosts
IGMPv3 has introduced source filtering modes (Include and Exclude), so that a host can specify a list of
sources it expect or does not expect multicast data from when it joins a multicast group:
If it expects multicast data from specific sources like S1, S2, ..., it sends a report with the
Filter-Mode denoted as "Include Sources (S1, S2, ...).
If it does not expect 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
both of which can send multicast data to multicast group G. Host B is interested only in the multicast
data that Source 1 sends to G but not in the data from Source 2.
Figure 1-2 Flow paths of source-and-group-specific multicast traffic
Source 1
Source 2
Packets (S1,G)
Packets (S2,G)
In the case of IGMPv1 or IGMPv2, Host B cannot select multicast sources when it joins multicast group
G. Therefore, multicast streams from both Source 1 and Source 2 will flow to Host B whether it needs
them or not.
When IGMPv3 is running between the hosts and routers, Host B can explicitly express its 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.
Enhancements in query and report capabilities
1) Query message carrying the source addresses
1-2, the network comprises two multicast sources, Source 1 (S1) and Source 2 (S2),
Host A
Receiver
Host B
Host C
1-4