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 4-10

(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 4-15

 

 

 

 

 

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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