Internet group multicast protocol (igmp) – Intel 460T User Manual
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Intel Express 460T Standalone Switch Users Guide
Internet Group Multicast Protocol (IGMP)
Generally, the switch broadcasts multicast traffic to all ports. For multicast
traffic based on the TCP/IP using the IGMP protocol, the switch can
optimize the broadcasting of multicast traffic by forwarding multicast traffic
only to ports that require it.
IGMP Snooping is a feature that allows the switch to forward multicast
traffic intelligently. The switch “snoops” the IGMP query and report
messages and forwards traffic only to the ports that request the multicast
traffic. This prevents the switch from broadcasting the traffic to all ports
and possibly affecting network performance.
IGMP requires a router that detects multicast groups on its subnets and
keeps track of group membership. Note that multicasting is not connection
oriented, so data is delivered to the requesting hosts on a best-effort level
of service.