3Com 8807 Configuration Manual page 443

Description of IGMP proxy configuration
Figure 108 A schematic diagram of IGMP proxy
Switch A Switch A Switch A Switch A Switch A
33.33.33.1 33.33.33.1 33.33.33.1 33.33.33.1 33.33.33.1
VL AN interface 1 VL AN interface 1 Vlan -interface 1 Vlan -interface 1 Vlan -interface 1
VL AN interface 100 VL AN interface 100 Vlan -interface 100 Vlan -interface 100 Vlan -interface 100
33.33.33.2 33.33.33.2 33.33.33.2
33.33.33.2 33.33.33.2
VL AN interface 200 VL AN interface 200
Switch B Switch B Switch B Switch B Switch B
Figure 108 illustrates how IGMP proxy works. In this figure:
Switch B is configured as follows:
Multicast is enabled.
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PIM and IGMP are configured on the interfaces of VLAN 100 and VLAN 200.
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The interface of VLAN 100 is configured as the IGMP proxy interface of the
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interface of VLAN 200.
Switch A is configured as follows:
Multicast is enabled.
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PIM and IGMP are configured on the interface of VLAN 100.
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The pim neighbor-policy command is executed in VLAN 100 interface view to
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filter the PIM neighbors of the network segment 33.33.33.0/24. That is,
prevent Switch B from being the PIM neighbor.
Operating mechanism of IGMP Proxy
The procedures to process IGMP join/leave messages are as follows:
After receiving an IGMP join/leave message sourced from a host through the
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interface of VLAN 200, Switch B changes the source address of the message to
the IP address of VLAN 100 interface (33.33.33.2), which is the outbound
interface leading to Switch A.
Switch B sends the IGMP message to Switch A.
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Normal group/Specific group Normal group/Specific group Normal group/Specific group
querying messages querying messages querying messages
IGMP join/leave messages IGMP join/leave messages IGMP join/leave messages
Vlan -interface 200 Vlan -interface 200 Vlan -interface 200
22.22.22.1 22.22.22.1 22.22.22.1 22.22.22.1 22.22.22.1
Introduction to IGMP Proxy
Exterior network Exterior network
Leaf network Leaf network
Host Host
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