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Example: Configuring IGMP Snooping

With IGMP snooping enabled, a switch monitors the IGMP (Internet Group Management Protocol) traffic between hosts and multicast routers and uses what it learns to forward multicast traffic to only the downstream interfaces that are connected to interested receivers. This conserves bandwidth by allowing the switch to send multicast traffic to only those interfaces that are connected to devices that want to receive the traffic (instead of flooding the traffic to all the downstream VLAN interfaces).

This example describes how to configure IGMP snooping:

Requirements

This example requires Junos OS Release 11.1 or later on a QFX Series product.

Before you configure IGMP snooping, be sure you have:

  • Configured the employee-vlan VLAN
  • Assigned interfaces ge-0/0/1, ge-0/0/2, and ge-0/0/3 to employee-vlan

Overview and Topology

In this example you configure an interface to receive multicast traffic from a source and configure some multicast-related behavior for downstream interfaces. The example assumes that IGMP snooping was previously disabled for the VLAN.

Table 1 shows the components of the topology for this example.

Table 1: Components of the IGMP Snooping Topology

Components

Settings

VLAN name

employee-vlan, tag 20

Interfaces in employee-vlan

ge-0/0/1, ge-0/0/2, ge-0/0/3

Multicast IP address for employee-vlan

225.100.100.100

Configuration

To configure basic IGMP snooping on a switch:

CLI Quick Configuration

To quickly configure IGMP snooping, copy the following commands and paste them into a terminal window:

[edit protocols]
set igmp-snooping vlan employee-vlan
set igmp-snooping vlan employee-vlan interface ge-0/0/3 static group 225.100.100.100
set igmp-snooping vlan employee-vlan interface ge-0/0/2 multicast-router-interface
set igmp-snooping vlan employee-vlan robust-count 4

Step-by-Step Procedure

Configure IGMP snooping:

  1. Enable and configure IGMP snooping on the VLAN employee-vlan:
    [edit protocols]
    user@switch# set igmp-snooping vlan employee-vlan
  2. Configure a interface to belong to a multicast group:
    [edit protocols]
    user@switch# set igmp-snooping vlan employee-vlan interface ge-0/0/3 static group 225.100.100.100
  3. Configure an interface to forward IGMP queries received from multicast routers.
    [edit protocols]
    user@switch# set igmp-snooping vlan employee-vlan interface ge-0/0/2 multicast-router-interface
  4. Configure the switch to wait for four timeout intervals before timing out a multicast group on a VLAN:
    [edit protocols]
    user@switch# set igmp-snooping vlan employee-vlan robust-count 4

Results

Check the results of the configuration:

user@switch# show protocols igmp-snoopingvlan employee-vlan {robust-count 4;}interface ge-0/0/2 {multicast-router-interface;}interface ge-0/0/3 {static {group 255.100.100.100;}}}
 

Related Documentation

 

Published: 2014-07-23

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