If you enable IGMP snooping on a VLT unit, IGMP snooping dynamically learned groups and multicast
router ports are made to learn on the peer by explicitly tunneling the received IGMP control packets.
IGMP Snooping Implementation Information
• IGMP snooping on Dell Networking OS uses IP multicast addresses not MAC addresses.
• IGMP snooping reacts to spanning tree protocol (STP) and multiple spanning tree protocol (MSTP)
topology changes by sending a general query on the interface that transitions to the forwarding state.
• If IGMP snooping is enabled on a PIM-enabled VLAN interface, data packets using the router as an
Layer 2 hop may be dropped. To avoid this scenario, Dell Networking recommends that users enable
IGMP snooping on server-facing end-point VLANs only.
Configuring IGMP Snooping
Configuring IGMP snooping is a one-step process. To enable, view, or disable IGMP snooping, use the
following commands.
There is no specific configuration needed for IGMP snooping with virtual link trunking (VLT). For
information about VLT configurations, refer to Virtual Link Trunking (VLT).
• Enable IGMP snooping on a switch.
CONFIGURATION mode
ip igmp snooping enable
• View the configuration.
CONFIGURATION mode
show running-config
• Disable snooping on a VLAN.
INTERFACE VLAN mode
no ip igmp snooping
Related Configuration Tasks
• Removing a Group-Port Association
• Disabling Multicast Flooding
• Specifying a Port as Connected to a Multicast Router
• Configuring the Switch as Querier
Example of ip igmp snooping enable Command
Dell(conf)#ip igmp snooping enable
Dell(conf)#do show running-config igmp
ip igmp snooping enable
Dell(conf)#
Removing a Group-Port Association
To configure or view the remove a group-port association feature, use the following commands.
• Configure the switch to remove a group-port association after receiving an IGMP Leave message.
INTERFACE VLAN mode
Internet Group Management Protocol (IGMP)
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