(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.
IS_EX: indicating the mapping relationship between the multicast group and the multicast
source list is EXCLUDE, which means the host will only receive the multicast data sending to
this multicast group with its source not in the specified source list.
TO_IN: indicating the mapping relationship between the multicast group and the multicast
source list changes from EXCLUDE to INCLUDE.
TO_EX: indicating the mapping relationship between the multicast group and the multicast
source list changes from INCLUDE to EXCLUDE.
ALLOW: indicating the host expects to receive multicast data from more multicast sources
besides the current ones. If the current mapping relationship is INCLUDE, these multicast
sources will be added to the multicast source list; if the current mapping relationship is
EXCLUDE, these multicast sources will be deleted from the multicast source list.
BLOCK: indicating the host doesn’t expect to receive multicast data from the specific
multicast sources any longer. If the current mapping relationship is INCLUDE, these
multicast sources will be deleted from the multicast source list; if the current mapping
relationship is EXCLUDE, these multicast sources will be added to the multicast source list.
11.2.1
Global Config
IGMP stands for Internet Group Management Protocol. It is responsible for the management of
IP multicast members in IPv4, and is used to establish and maintain the multicast member
relationships between the IP host and its directly neighboring multicast routers.
Choose the menu
Multicast Routing→IGMP→Global Config
to load the following page.
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