Concept Guide

• Adjust the maximum response time.
INTERFACE mode
ip igmp query-max-resp-time
• Adjust the maximum amount of time that the querier waits, for an IPv6 query response, before taking further action.
Interface mode
ipv6 mld query-max-response-time
• Adjust the last member query interval.
INTERFACE mode
ip igmp last-member-query-interval
• Adjust the amount of time the querier waits, for the initial query response, before sending the next IPv6 query.
Interface mode
ipv6 mld last-member-query-interval
Enabling IGMP Immediate-Leave
If the querier does not receive a response to a group-specic or group-and-source query, it sends another (querier robustness value). Then,
after no response, it removes the group from the outgoing interface for the subnet.
IGMP immediate leave reduces leave latency by enabling a router to immediately delete the group membership on an interface after
receiving a Leave message (it does not send any group-specic or group-and-source queries before deleting the entry).
• Congure the system for IGMP immediate leave.
ip igmp immediate-leave
• Congure the system to immediately delete the IPv6 group membership on an interface after receiving a leave message.
ipv6 mld immediate-leave
• View the enable status of the IGMP immediate leave feature.
EXEC Privilege mode
show ip igmp interface
show ipv6 mld interface
View the enable status of this feature using the command from EXEC Privilege mode, as shown in the example in Selecting an IGMP
Version.
IGMP Snooping
IGMP snooping enables switches to use information in IGMP packets to generate a forwarding table that associates ports with multicast
groups so that when they receive multicast frames, they can forward them only to interested receivers.
Multicast packets are addressed with multicast MAC addresses, which represent a group of devices, rather than one unique device.
Switches forward multicast frames out of all ports in a virtual local area network (VLAN) by default, even though there may be only some
interested hosts, which is a waste of bandwidth.
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 EMC Networking OS uses IP multicast addresses not MAC addresses.
• IGMP snooping is supported on all stack members.
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Internet Group Management Protocol (IGMP)