Igmp Snooping - Intellinet 560900 User Manual

4.1.8 IGMP Snooping

IGMP Snooping is the process of listening to IGMP network traffic. IGMP Snooping, as implied
by the name, is a feature that allows a Layer 2 switch to "listen in" on the IGMP conversation
between hosts and routers by processing the Layer 3 IGMP packets sent in a multicast
network. When IGMP Snooping is enabled in a switch, it analyzes all IGMP packets between
hosts connected to the switch and multicast routers in the network. When a switch hears an
IGMP report from a host for a given multicast group, the switch adds the host's port number to
the multicast list for that group. And, when the switch hears an IGMP Leave, it removes the
host's port from the table entry. It also prevents flooding of IP multicast traffic, and limits
bandwidth-intensive video traffic to only the subscribers.
IGMP Configuration
 IGMP Enabled: When this is enabled, the switch will monitor network traffic to determine
which hosts want to receive multicast traffic.
 Router Ports: Set if ports are connecting to the IGMP administrative routers.
 Unregistered IPMC Flooding enabled: Set the forwarding mode for unregistered (not-joined)
IP multicast traffic. The traffic will flood when enabled, and forward to router ports only
when disabled.
 IGMP Snooping Enabled: When enabled, the port will monitor network traffic to determine
which hosts want to receive the multicast traffic.
 IGMP Querying Enabled: When enabled, the port can serve as the Querier, which is
responsible for asking hosts if they want to receive multicast traffic.
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