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The IGMP snooping proxy device processes different IGMP messages as follows:
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General query.
After receiving an IGMP general query, the device forwards the query to all ports in the VLAN
except the receiving port. The device also generates an IGMP report based on the local
membership information and sends the report to all router ports.
•
Group-specific query or group-and-source-specific query.
After receiving an IGMP group-specific query or group-and-source-specific query, the device
forwards the query to all ports in the VLAN except the receiving port. If the forwarding entry has
a member port, the device sends a report to all router ports in the VLAN.
•
Report.
After receiving an IGMP report from a host, the device looks up the forwarding table for a
matching entry as follows:
If a match is found and the matching forwarding entry contains the receiving port, the device
resets the aging timer for the port.
If a match is found but the matching forwarding entry does not contain the receiving port, the
device adds the receiving port to the outgoing interface list. It also marks the receiving port
as a dynamic member port and starts an aging timer for the port.
If no match is found, the device creates a forwarding entry with the receiving port as an
outgoing interface. It also marks the receiving port as a dynamic member port and starts an
aging timer for the port. Then it sends the report to all router ports.
•
Leave message.
After receiving the IGMP leave message on a port, the device sends an IGMP group-specific
query through the receiving port. The device sends the IGMP leave message to all router ports
only when the last member port is removed from the forwarding entry.
Protocols and standards
RFC 4541,
Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener
Discovery (MLD) Snooping Switches
IGMP snooping configuration task list
You can configure IGMP snooping for VLANs or VSIs.
IGMP snooping configuration task list for VLANs
Tasks at a glance
Configuring basic IGMP snooping features
•
•
(Optional.)
Specifying an IGMP snooping version
•
(Optional.)
Setting the maximum number of IGMP snooping forwarding entries
•
(Optional.) Configuring static multicast MAC address entries
•
(Optional.) Setting the IGMP last member query interval
Configuring IGMP snooping port features
•
(Optional.)
Setting aging timers for dynamic ports
•
(Optional.)
•
(Optional.)
Configuring a port as a simulated member host
•
(Optional.)
Enabling fast-leave processing
•
(Optional.)