Configuring Multicast Forwarding
IGMP Snooping
Cisco Small Business 300 Series Managed Switch Administration Guide  156
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There should be only one IGMP Querier in a Layer 2 Multicast domain. The switch 
supports standards-based IGMP Querier election when more than one IGMP 
Querier is present in the domain.
The speed of IGMP Querier activity should be aligned with the IGMP-snooping-
enabled switches. Queries should be sent at a rate that is aligned to the snooping 
table aging time. If queries are sent at a rate lower than the aging time, the 
subscriber cannot receive the Multicast packets.
To enable IGMP Snooping and identify the switch as an IGMP Snooping Querier on 
a VLAN:
STEP 1 Click Multicast > IGMP Snooping. The 
IGMP Snooping Page
 opens.
The IGMP Snooping Table displays the IGMP snooping information for the VLANs 
on the switch. The columns are described in STEP 4. 
STEP  2 Check Enable (or disable) the IGMP Snooping status. 
IGMP Snooping Status globally enables the device monitoring network traffic to 
determine which hosts have requested to receive Multicast traffic. The switch 
performs IGMP Snooping if IGMP snooping and Bridge Multicast filtering are both 
enabled.
STEP  3 Select a VLAN, and click Edit. The 
Edit IGMP Snooping Page 
opens.
There should be only one IGMP Querier in a network. The switch supports 
standards-based IGMP Querier election. Some of the values of the operational 
parameters of this table are sent by the elected querier. The other values are 
derived from the switch.
STEP  4 Enter the parameters.
• VLAN ID—Select the VLAN ID where IGMP snooping is defined.
• IGMP Snooping Status—Enable or disable the monitoring of network traffic 
to determine which hosts have asked to be sent Multicast traffic. The switch 
performs IGMP snooping only if IGMP snooping and Bridge Multicast 
filtering are both enabled.
• Operational IGMP Snooping Status—Displays the current status of the 
IGMP Snooping for the selected VLAN.
• MRouter Ports Auto Learn—Enable or disable auto learning of the ports to 
which the Mrouter is connected. 
• Query Robustness—Enter the Robustness Variable value to be used if this 
switch is the elected querier.