Users Guide

Internet address is 1.1.1.1/24
IGMP is enabled on interface
IGMP query interval is 60 seconds
IGMP querier timeout is 125 seconds
IGMP max query response time is 10 seconds
IGMP last member query response interval is 1000 ms
IGMP immediate-leave is disabled
IGMP activity: 0 joins, 0 leaves, 0 channel joins, 0 channel leaves
IGMP querying router is 1.1.1.1 (this system)
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.
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.
Internet Group Management Protocol (IGMP) 405