Users Guide

IGMP version is 3
Dell(conf-if-te-1/13)#
Viewing IGMP Groups
To view both learned and statically configured IGMP groups, use the following command.
• View both learned and statically configured IGMP groups.
EXEC Privilege mode
show ip igmp groups
Example of the show ip igmp groups Command
Dell#show ip igmp groups
Total Number of Groups: 2
IGMP Connected Group Membership
Group Address Interface Mode Uptime Expires
Last Reporter
225.1.1.1 TenGigabitEthernet 1/0 IGMPv2-Compat 00:00:06 00:02:03
1.1.1.2
225.1.1.2 TenGigabitEthernet 1/0 IGMPv2-Compat 00:00:06 00:02:03
1.1.1.2
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 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.
Internet Group Management Protocol (IGMP)
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