Igmp Proxy - Huawei Quidway S5600 Series Operation Manual

Operation Manual – Multicast Protocol
Quidway S5600 Series Ethernet Switches-Release 1510
All the hosts and routers in the network receive the IGMP host report packets and
get to know the address of the multicast group G1. In this case, if other hosts in
the network want to join in the multicast group G1, they will not send IGMP host
report packets about G1. If some hosts in the network want to join in another
multicast group G2, they will send IGMP host report packets about G2 to respond
to the query messages.
After the query/response process, the IGMP routers get to know that receivers
corresponding to the multicast group G1 exist in the network, and generate the (*,
G1) multicast forwarding entries, according to which the multicast information is
forwarded.
The data from the multicast source reaches the IGMP router through the
multicast routes. If there are receivers in the network connected to the IGMP
router, the data will be forwarded to this network segment and the receiver hosts
receive the data.
IGMP leave packet is not defined in IGMPv1, so when a host leaves a multicast group,
only when a query message times out can the multicast router know that a host has left
the group.
When all the hosts in a network segment have left the multicast group, the branch
corresponding to the related network segment is pruned from the multicast tree.

6.1.4 IGMP Proxy

A lot of leaf networks (leaf domains) are involved in the application of a multicast routing
protocol (PIM-DM for example) over a large-scaled network. It is a hard work to
configure and manage these leaf networks.
To reduce the workload of configuration and management without affecting the
multicast connection of leaf networks, you can configure an IGMP Proxy in a Layer 3
switch in the leaf network (Switch B in the figure). The Layer 3 switch will then forward
IGMP join or IGMP leave messages sent by the connected hosts. After the
configuration of IGMP Proxy, the leaf switch is no longer a PIM neighbor but a host for
the external network. Only when the Layer 3 switch has directly connected members,
can it receive the multicast data of corresponding groups.
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6-4
Chapter 6 IGMP Configuration