Multimedia Traffic Control with IP Multicast (IGMP)
General Operation and Features
General Operation and Features
IGMP Features
Feature Default Menu CLI Web
view igmp configuration n/a — page 4-6 —
show igmp status for multicast n/a — Yes —
groups used by the selected
VLAN
enabling or disabling IGMP disabled — page 4-8 page 4-11
(Requires VLAN ID Context)
per-port packet control auto — page 4-9 —
IGMP traffic priority normal — page 4-10 —
querier enabled — page 4-10 —
fast-leave disabled — page 4-14 —
In a network where IP multicast traffic is transmitted for various multimedia
applications, you can use the switch to reduce unnecessary bandwidth usage
on a per-port basis by configuring IGMP (Internet Group Management
Protocol controls). In the factory default state (IGMP disabled), the switch
simply floods all IP multicast traffic it receives on a given VLAN through all
ports on that VLAN (except the port on which it received the traffic). This can
result in significant and unnecessary bandwidth usage in networks where IP
multicast traffic is a factor. Enabling IGMP allows the ports to detect IGMP
queries and report packets and manage IP multicast traffic through the switch.
IGMP is useful in multimedia applications such as LAN TV, desktop
conferencing, and collaborative computing, where there is multipoint
communication; that is, communication from one to many hosts, or
communication originating from many hosts and destined for many other
hosts. In such multipoint applications, IGMP will be configured on the hosts,
and multicast traffic will be generated by one or more servers (inside or
outside of the local network). Switches in the network (that support IGMP)
can then be configured to direct the multicast traffic to only the ports where
needed. If multiple VLANs are configured, you can configure IGMP on a per-
VLAN basis.
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