Example: Configuring IGMP Snooping on EX Series Switches
IGMP snooping regulates multicast traffic in a switched network. With IGMP snooping enabled, a LAN switch monitors the IGMP transmissions between a host (a network device) and a multicast router, keeping track of the multicast groups and associated member ports. The switch uses that information to make intelligent multicast-forwarding decisions and forward traffic to the intended destination interfaces.
Configure IGMP snooping on one or more VLANs to allow the switch to examine IGMP packets and make forwarding decisions based on packet content. By default, IGMP snooping is enabled on EX Series switches.
This example describes how to configure IGMP snooping:
Requirements
This example uses the following software and hardware components:
- One EX3200-24T switch
- Junos OS Release 9.5 or later for EX Series switches
Before you configure IGMP snooping, be sure you have:
- Configured the employee-vlan VLAN on the switch
- Assigned interfaces ge-0/0/1, ge-0/0/2, and ge-0/0/3 to employee-vlan
See Example: Setting Up Bridging with Multiple VLANs for EX Series Switches.
Overview and Topology
IGMP snooping controls multicast traffic in a switched network. With IGMP snooping enabled, an EX Series switch monitors the IGMP transmissions between a host and a multicast router to keep track of the multicast groups and associated member ports. The switch uses this information to make intelligent decisions and forward multicast traffic to the intended destination interfaces.
You can configure IGMP snooping on all interfaces in a VLAN or on individual interfaces. This example shows how to configure IGMP snooping on an EX Series switch.
The configuration setup for this example includes the VLAN employee-vlan on the switch.
Table 1 shows the components of the topology for this example.
Table 1: Components of the IGMP Snooping Topology
| Properties | Settings |
|---|---|
Switch hardware | One EX3200-24T switch |
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 |
In this example, the switch is initially configured as follows:
- IGMP snooping is disabled on the VLAN.
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 the switch terminal window:
[edit protocols]
set
igmp-snooping vlan employee-vlan
set igmp-snooping vlan employee-vlan interface ge-0/0/1 group-limit
50
set igmp-snooping vlan
employee-vlan immediate-leave
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:
- Enable and configure IGMP snooping on the VLAN employee-vlan:
[edit protocols]
user@switch# set igmp-snooping vlan employee-vlan - Configure the limit for the number of multicast
groups allowed on the ge-0/0/1 interface to 50.
[edit protocols]
user@switch# set igmp-snooping vlan employee-vlan interface ge-0/0/1 group-limit 50 - Configure the switch to immediately remove a group
membership from an interface when it receives a leave message from
that interface without waiting for any other IGMP messages to be exchanged
(IGMPv2 only):
[edit protocols]
user@switch# set igmp-snooping vlan employee-vlan immediate-leave - Statically configure IGMP group membership on a
port:
[edit protocols]
user@switch# set igmp-snooping vlan employee-vlan interface ge-0/0/3.0 static (IGMP Snooping) group 225.100.100.100 - Statically configure an interface as a switching
interface toward a multicast router (the interface to receive multicast
traffic):
[edit protocols]
user@switch# set igmp-snooping vlan employee-vlan interface ge-0/0/2 multicast-router-interface - Change the number of timeout intervals the switch
waits before timing out a multicast group to 4:
[edit protocols]
user@switch# set igmp-snooping vlan employee-vlan robust-count 4
Results
Check the results of the configuration:
