Dell S4820T, Configuration Manual

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INTERFACE VLAN mode
ip igmp snooping querier
IGMP snooping querier does not start if there is a statically configured multicast router interface in the
VLAN.
The switch may lose the querier election if it does not have the lowest IP address of all potential
queriers on the subnet.
When enabled, IGMP snooping querier starts after one query interval in case no IGMP general query
(with IP SA lower than its VLAN IP address) is received on any of its VLAN members.
Adjusting the Last Member Query Interval
To adjust the last member query interval, use the following command.
When the querier receives a Leave message from a receiver, it sends a group-specific query out of the
ports specified in the forwarding table. If no response is received, it sends another. The amount of time
that the querier waits to receive a response 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-port entry from the forwarding table.
• Adjust the last member query interval.
INTERFACE VLAN mode
ip igmp snooping last-member-query-interval
Fast Convergence after MSTP Topology Changes
The following describes the fast convergence feature.
When a port transitions to the Forwarding state as a result of an STP or MSTP topology change, Dell
Networking OS sends a general query out of all ports except the multicast router ports. The host sends a
response to the general query and the forwarding database is updated without having to wait for the
query interval to expire.
When an IGMP snooping switch is not acting as a querier, it sends out the general query in response to
the MSTP triggered link-layer topology change, with the source IP address of 0.0.0.0 to avoid triggering
querier election.
Egress Interface Selection (EIS) for HTTP and IGMP
Applications
You can use the Egress Interface Selection (EIS) feature to isolate the management and front-end port
domains for HTTP and IGMP traffic. Also, EIS enables you to configure the responses to switch-destined
traffic by using the management port IP address as the source IP address. This information is sent out of
the switch through the management port instead of the front-end port.
Internet Group Management Protocol (IGMP)
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