Introduction - Allied Telesis SwitchBlade x908 Series Software Reference Manual

IGMP Snooping Configuration

Introduction

This chapter provides steps to configure Internet Group Management Protocol (IGMP)
snooping. To see details on the commands used in this example, or to see the outputs of the
validation commands, refer to
Without IGMP snooping, Layer-2 switches handle IP multicast traffic in the same manner as
broadcast traffic, and forward multicast frames received on one port to all other ports in the
same VLAN. This creates excessive traffic on the network, and affects network performance.
IGMP Snooping allows switches to monitor network traffic, and determine hosts to receive
multicast traffic.
This example describes the configuration on an Allied Telesis managed Layer 3 Switch (switch
1). The interface, port1.0.12, is configured as a multicast router port. Host A and Host B are
both members of the same multicast group.
To enable IGMP Snooping on an interface:
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As a result of this configuration:
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40.2
Chapter 41, IGMP Multicast
Enable IGMP Snooping globally, if necessary.
Statically configure ports that are connected to routers if necessary.
By default, IGMP report suppression is enabled on the switch.
Switch 1
port1.0.1 port1.0.2
Host A
The switch replies back with Membership report messages in response to queries received
on interface port1.0.12.
Because Host A and Host B are members of the same multicast group, the switch does
not notify the IP IGMP routing device (device 1) when Host A leaves the group, because
the group still has another member Host B remaining. When Host B also leaves the group,
the switch sends a Leave message to the IP IGMP routing device with the destination
address as 224.0.0.2 (All Router Destination Address).
The addition of a static mrouter port is only required when there is no upstream IGMP
querier or an upstream router does not send topology discovery or maintenance
messages (like IGMP General Queries or OSPF Hello packets).
In this example, it is not necessary to distinguish to the switch whether this is an IGMPv2 or
IGMPv3 based multicast network.
Software Reference for SwitchBlade® x908, x900 and x600 Series Switches
TM
AlliedWare Plus Operating System - Software Version 5.3.1
Commands.
port1.0.12 port1.0.1
Host B
Device 1
igmpsnoop_1
C613-50007-01 REV B