Multimedia Traffic Control with IP Multicast (IGMP)

Overview

Overview

IGMP Features

Feature

Default

Menu

CLI

Web

 

 

 

 

 

view igmp configuration

n/a

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show igmp status for multicast

n/a

Yes

groups used by the selected

 

 

 

 

VLAN

 

 

 

 

enabling or disabling IGMP

disabled

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(Requires VLAN ID Context)

 

 

 

 

per-port packet control

auto

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IGMP traffic priority

normal

page 12-8

querier

enabled

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Without IGMP enabled, 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. Data- Driven IGMP reduces this problem by authorizing the switch to restrict multicast traffic only to ports where a given multicast group should flow. Series 5300XL switches use data-driven IGMP to better control IP multicast traffic.

In a network where IP multicast traffic is transmitted for various multimedia applications, you can use IGMP on the switch to reduce unnecessary bandwidth usage on a per-port basis. In the factory default state (IGMP disabled), the switch forwards all IGMP traffic to all ports, which can cause unnecessary bandwidth usage on ports not belonging to multicast groups. 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 confer­ encing, and collaborative computing, where there is multipoint communica­ tion; 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

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