TP-Link T3700G-28TQ T3700G-28TQ V1 UG - Page 227

Function Enhancement of the Query and Report Message, IGMPv3 Multicast Source Filtering

Page 227 highlights

Figure 11-4 IGMPv3 Multicast Source Filtering If the IGMP protocol running between the hosts and the multicast routers is IGMPv1 or IGMPv2, Host B will be unable to select its expecting sources when it joins the multicast group G. Thus whether needed or not, the multicast data from Source 1 and Source 2 will be transferred to Host B. When IGMPv3 is running between the hosts and the multicast routers, Host B will only expect the multicast data sending from Source 1 to G, referred as (S1, G), or refuse to receive the multicast data sending from Source 2 to G, referred as (S2, G). Thus only the multicast data from Source 1 will be transferred to Host B. 2. Function Enhancement of the Query and Report Message (1) Query message carrying source address IGMPv3 supports source-specific query as well as the general query in IGMPv1 and the group-specific query in IGMPv2:  The general query message carries neither group address nor source address;  The group-specific query message carries the group address without the source address.  The source-specific query message carries not only the group address, but also one or several source addresses. (2) The report message carrying several group records The destination address of IGMPv3 report message is 224.0.0.22. The IGMPv3 report message can carry one or several group records, which contains the list of multicast group addresses and multicast source addresses in each of them. The types of group records are listed as below:  IS_IN: indicating the mapping relationship between the multicast group and the multicast source list is INCLUDE, which means the host will only receive the multicast data sending from the specified multicast source list to this multicast group. If the specified multicast source list is empty here, the host will leave this group. 216

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Figure 11-4 IGMPv3 Multicast Source Filtering
If the IGMP protocol running between the hosts and the multicast routers is IGMPv1 or IGMPv2,
Host B will be unable to select its expecting sources when it joins the multicast group G. Thus
whether needed or not, the multicast data from Source 1 and Source 2 will be transferred to Host
B.
When IGMPv3 is running between the hosts and the multicast routers, Host B will only expect the
multicast data sending from Source 1 to G, referred as (S1, G), or refuse to receive the multicast
data sending from Source 2 to G, referred as (S2, G). Thus only the multicast data from Source 1
will be transferred to Host B.
2.
Function Enhancement of the Query and Report Message
(1) Query message carrying source address
IGMPv3 supports source-specific query as well as the general query in IGMPv1 and the
group-specific query in IGMPv2:
The general query message carries neither group address nor source address;
The group-specific query message carries the group address without the source address.
The source-specific query message carries not only the group address, but also one or several
source addresses.
(2)
The report message carrying several group records
The destination address of IGMPv3 report message is 224.0.0.22. The IGMPv3 report message
can carry one or several group records, which contains the list of multicast group addresses and
multicast source addresses in each of them. The types of group records are listed as below:
IS_IN: indicating the mapping relationship between the multicast group and the multicast
source list is INCLUDE, which means the host will only receive the multicast data sending
from the specified multicast source list to this multicast group. If the specified multicast source
list is empty here, the host will leave this group.
216