Enabling Igmp Immediate-Leave; Igmp Snooping - Dell S4820T Configuration Manual

to the initial query before sending a second one is the last member query interval (LMQI). The switch
waits one LMQI after the second query before removing the group from the state table.
• Adjust the period between queries.
INTERFACE mode
ip igmp query-interval
• Adjust the maximum response time.
INTERFACE mode
ip igmp query-max-resp-time
• Adjust the last member query interval.
INTERFACE mode
ip igmp last-member-query-interval

Enabling IGMP Immediate-Leave

If the querier does not receive a response to a group-specific 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-specific or
group-and-source queries before deleting the entry).
• Configure the system for IGMP immediate leave.
ip igmp immediate-leave
• View the enable status of the IGMP immediate leave feature.
EXEC Privilege mode
show ip igmp interface
View the enable status of this feature using the command from EXEC Privilege mode, as shown in the
example in Selecting an IGMP

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.
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Internet Group Management Protocol (IGMP)