Introduction To Igmp Proxy - H3C S9500 Series Operation Manual

Operation Manual – Multicast Protocol
H3C S9500 Series Routing Switches
address is elected as the querier when there are multiple multicast routers on the same
network segment.
II. Leaving group mechanism
In IGMP Version 1, hosts leave the multicast group quietly without informing the
multicast router. In this case, the multicast router can only depend on the timeout of the
response time of the multicast group to confirm that hosts leave the group. In Version 2,
when a host is intended to leave, it will send a leave group message if it is the host who
responds to the latest membership query message.
III. Specific group query
In IGMP Version 1, a query of a multicast router is targeted at all the multicast groups
on the network segment, which is known as General Query.
In IGMP Version 2, Group-Specific Query is added besides general query. The
destination IP address of the query packet is the IP address of the multicast group. The
group address domain in the packet is also the IP address of the multicast group. This
prevents the hosts of members of other multicast groups from sending response
messages.
IV. Max response time
The Max Response Time is added in IGMP Version 2. It is used to dynamically adjust
the allowed maximum time for a host to respond to the group query message.

5.1.2 Introduction to IGMP Proxy

For a large scale PIM-DM (protocol independent multicast-dense mode) network with
multicast routing protocol employed, many leaf networks may exist (a leaf network here
refers to an end node of a multicast forwarding tree, it is a subnet that contains
multicast clients only). It is a heavy load to configure and manage all these leaf
networks.
You can ease the workload of configuring and managing leaf networks without affecting
the multicast connections in them by enabling IGMP proxy on devices in these leaf
networks.
After IGMP proxy is configured, the devices in leaf networks act as a host to the exterior
network. They receive the multicast data of the associated group only when some of
the hosts directly connected to them are multicast group members.
5-2
Chapter 5 IGMP Configuration