The unknown multicast filtering is enabled by default on the switch. The IGMP Multicast Flood Control functionality is provided when IGMP snooping is enabled.
When IGMP snooping is enabled on a VLAN, IGMP multicast flood control is also enabled on that VLAN.
On ERS 4900/5900 it is enabled by default on the switch with no way to disable it manually as it was on ERS 4800.
IGMP fast leave can be configured by using the ‘ip igmp last-member-query-interval [0-255]’ command.
It specifies the last member query interval value in 1/10 of a second. Extreme Networks recommends that you configure this parameter to values higher than 3. If a fast leave process is not required the values above 10 are recommended.