Users Guide

ip igmp snooping mrouter
● View the ports that are connected to multicast routers.
EXEC Privilege mode.
show ip igmp snooping mrouter
Configuring the Switch as Querier
To configure the switch as a querier, use the following command.
Hosts that do not support unsolicited reporting wait for a general query before sending a membership report. When the
multicast source and receivers are in the same VLAN, multicast traffic is not routed and so there is no querier. Configure the
switch to be the querier for a VLAN so that hosts send membership reports and the switch can generate a forwarding table by
snooping.
● Configure the switch to be the querier for a VLAN by first assigning an IP address to the VLAN interface.
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
When a port transitions to the Forwarding state as a result of an STP or MSTP topology change, Dell EMC 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.
The management EIS feature is applicable only for the out-of-band (OOB) management port. References in this section to
the management default route or static route denote the routes configured using the management route command. The
management default route can be either configured statically or returned dynamically by the DHCP client. A static route points
to the management interface or a forwarding router.
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Internet Group Management Protocol (IGMP)