IGMP snooping querier configuration example (for VLANs)

As shown in Figure 16:

• The network is a Layer 2-only network.

• Source 1 and Source 2 send multicast data to multicast groups 224.1.1.1 and 225.1.1.1, respectively.

• Host A and Host C are receivers of multicast group 224.1.1.1, and Host B and Host D are receivers of multicast group 225.1.1.1.

• All host receivers run IGMPv2, and all switches run IGMPv2 snooping. Switch A (which is close to the multicast sources) acts as the IGMP snooping querier.

Configure the switches to meet the following requirements:

• To prevent the switches from flooding unknown data in the VLAN, enable all the switches to drop unknown multicast data.

• A switch does not mark a port that receives an IGMP query with source IP address 0.0.0.0 as a dynamic router port. This adversely affects the establishment of Layer 2 forwarding entries and multicast traffic forwarding. To avoid this, configure the source IP address of IGMP queries as a non-zero IP address.

1. Configure Switch A:

   # Enable the IGMP snooping feature.

   <SwitchA> system-view
   [SwitchA] igmp-snooping
   [SwitchA-igmp-snooping] quit
   

   # Create VLAN 100, and assign Ten-GigabitEthernet 1/0/1 through Ten-GigabitEthernet 1/0/3 to the VLAN.

   [SwitchA] vlan 100
   [SwitchA-vlan100] port ten-gigabitethernet 1/0/1 to ten-gigabitethernet 1/0/3
   

   # Enable IGMP snooping, and enable dropping unknown multicast data for VLAN 100.

   [SwitchA-vlan100] igmp-snooping enable
   [SwitchA-vlan100] igmp-snooping drop-unknown
   

   # Configure Switch A as the IGMP snooping querier.

   [SwitchA-vlan100] igmp-snooping querier
   [SwitchA-vlan100] quit
   

   # In VLAN 100, specify 192.168.1.1 as the source IP address of IGMP general queries.

   [SwitchA-vlan100] igmp-snooping general-query source-ip 192.168.1.1
   

   # In VLAN 100, specify 192.168.1.1 as the source IP address of IGMP group-specific queries.

   [SwitchA-vlan100] igmp-snooping special-query source-ip 192.168.1.1
   [SwitchA-vlan100] quit
   

2. Configure Switch B:

   # Enable the IGMP snooping feature.

   <SwitchB> system-view
   [SwitchB] igmp-snooping
   [SwitchB-igmp-snooping] quit
   

   # Create VLAN 100, and assign Ten-GigabitEthernet 1/0/1 through Ten-GigabitEthernet 1/0/4 to the VLAN.

   [SwitchB] vlan 100
   [SwitchB-vlan100] port ten-gigabitethernet 1/0/1 to ten-gigabitethernet 1/0/4
   

   # Enable IGMP snooping, and enable dropping unknown multicast data for VLAN 100.

   [SwitchB-vlan100] igmp-snooping enable
   [SwitchB-vlan100] igmp-snooping drop-unknown
   [SwitchB-vlan100] quit
   

3. Configure Switch C:

   # Enable the IGMP snooping feature.

   <SwitchC> system-view
   [SwitchC] igmp-snooping
   [SwitchC-igmp-snooping] quit
   

   # Create VLAN 100, and assign Ten-GigabitEthernet 1/0/1 through Ten-GigabitEthernet 1/0/3 to the VLAN.

   [SwitchC] vlan 100
   [SwitchC-vlan100] port ten-gigabitethernet 1/0/1 to ten-gigabitethernet 1/0/3
   

   # Enable IGMP snooping, and enable dropping unknown multicast data for VLAN 100.

   [SwitchC-vlan100] igmp-snooping enable
   [SwitchC-vlan100] igmp-snooping drop-unknown
   [SwitchC-vlan100] quit
   

4. Configure Switch D:

   # Enable the IGMP snooping feature.

   <SwitchD> system-view
   [SwitchD] igmp-snooping
   [SwitchD-igmp-snooping] quit
   

   # Create VLAN 100, and assign Ten-GigabitEthernet 1/0/1 and Ten-GigabitEthernet 1/0/2 to the VLAN.

   [SwitchD] vlan 100
   [SwitchD-vlan100] port ten-gigabitethernet 1/0/1 to ten-gigabitethernet 1/0/2
   

   # Enable IGMP snooping, and enable dropping unknown multicast data for VLAN 100.

   [SwitchD-vlan100] igmp-snooping enable
   [SwitchD-vlan100] igmp-snooping drop-unknown
   [SwitchD-vlan100] quit
   

# Display statistics for IGMP messages and PIMv2 hello messages learned through IGMP snooping on Switch B.

[SwitchB] display igmp-snooping statistics
Received IGMP general queries:  3
Received IGMPv1 reports:  0
Received IGMPv2 reports:  12
Received IGMP leaves:  0
Received IGMPv2 specific queries:  0
Sent     IGMPv2 specific queries:  0
Received IGMPv3 reports:  0
Received IGMPv3 reports with right and wrong records:  0
Received IGMPv3 specific queries:  0
Received IGMPv3 specific sg queries:  0
Sent     IGMPv3 specific queries:  0
Sent     IGMPv3 specific sg queries:  0 
Received PIMv2 hello:  0
Received error IGMP messages:  0

The output shows that all switches except Switch A can receive the IGMP general queries after Switch A acts as the IGMP snooping querier.