Service Manual

ip igmp snooping querier
IGMP snooping querier does not start if there is a statically congured 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-specic query out of the ports specied 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
trac. Also, EIS enables you to congure the responses to switch-destined trac 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 congured using the management route command. The
management default route can be either congured statically or returned dynamically by the DHCP client. A static route points to the
management interface or a forwarding router.
Transit trac (destination IP not congured in the switch) that is received on the front-end port with destination on the
management port is dropped and received in the management port with destination on the front-end port is dropped.
Switch-destined trac (destination IP congured in the switch) is:
• Received in the front-end port with destination IP equal to management port IP address or management port subnet broadcast
address is dropped.
• Received in the management port with destination IP not equal to management IP address or management subnet broadcast
address is dropped.
Trac (switch initiated management trac or responses to switch-destined trac with management port IP address as the source
IP address) for user-specied management protocols must exit out of the management port. In this chapter, all the references to
trac indicate switch-initiated trac and responses to switch-destined trac with management port IP address as the source IP
address.
Internet Group Management Protocol (IGMP)
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