Users Guide

IGMP Snooping Implementation Information
• IGMP snooping 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
• Specifying a Port as Connected to a Multicast Router
• Removing a Group-Port Association
• Disabling Multicast Flooding
• 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
ip igmp fast-leave
• View the configuration.
INTERFACE VLAN mode
show config
Internet Group Management Protocol (IGMP) 406