Internet Group Management Protocol (IGMP) snooping allows a switch to forward multicast traffic intelligently. Multicast IP traffic is destined to a host group. Host groups are identified by class D IP addresses, which range from 224.0.0.0 to 239.255.255.255.
Based on the IGMP query and report messages, the switch forwards traffic only to the ports that request the multicast traffic. This prevents the switch from broadcasting the traffic to all ports and possibly affecting network performance.
Current NETGEAR fully managed switches support IGMP Plus mode. This mode lets you automatically configure IGMP snooping, which is used to build forwarding lists for IPv4 multicast traffic. You can also manually configure IGMP snooping.
IGMP snooping requires that one central switch or router periodically query all end-devices on the network to announce their multicast memberships. This central device is the IGMP querier. The IGMP query responses, known as IGMP reports, keep the switch updated with the current multicast group membership on a port-by-port basis. If the switch does not receive updated membership information in a timely fashion, it stops forwarding multicasts to the port where the end device is located. You can configure and display information for IGMP snooping queriers on the network and, separately, on VLANs.
This article describes how you can enable the IGMP snooping querier on VLAN 1 using CLI commands on a NETGEAR fully managed switch. For information about how to use the main user interface (UI), see How do I enable the Internet Group Management Protocol (IGMP) snooping querier using the main user interface on my NETGEAR fully managed switch?
The following example enables the snooping querier for VLAN 1 and uses 10.10.10.1 as the source IP address in querier packets. IGMP packets are then transmitted to every port on the VLAN.
To use CLI commands to enable the switch to generate IGMP querier packets for a VLAN:
(Netgear switch) #vlan database
(Netgear switch) (vlan)#set igmp 1
(Netgear switch) (vlan)#set igmp querier 1
(Netgear switch) (vlan)#exit
(Netgear switch) #config
(Netgear switch) (config)#set igmp querier
(Netgear switch) (config)#set igmp querier address 10.10.10.1
(Netgear switch) (config)#exit
For more information about IGMP snooping and IGMP snooping querier commands, see the CLI Command Reference Manual for your switch. You can download this manual by visiting the NETGEAR Download Center.