Igmp Snooping; Example - Allied Telesis AR400 Series How To Configure

IGMP snooping

In this example, we discuss IGMP snooping, the key to efficient multicast traffic flow in a
layer 2 network. IGMP snooping is enabled by default on switch ports in Allied Telesis
managed layer 3 switches and routers—it does not require any configuration.
In a single-switch network, IGMP snooping makes multicasting happen with no configuration
at all. All you need to do is connect your server and clients to the switch.
In a multi-switch network, at least one switch must also have an IGMP configuration. This
switch is called the IGMP Querier and coordinates the flow of multicast information through
the network. The following example describes a multi-switch configuration, so as well as
discussing the effect of IGMP snooping, it outlines the actions that the Querier takes.
"Multiple potential IGMP queriers" on page 15
detail.

Example

This example has a 3-switch loop, as shown in the following figure. One of the switches is
running IGMP and the other two switches are running IGMP snooping.
Page 9 | AlliedWare™ OS How To Note: IGMP
Multicast Server
port 26
Rapier 24i
Switch 2:
Snooper
port 2
Client 1
discusses the role of the Querier in greater
port 1
AT-8948
Switch 1:
Querier
port 50 port 49
(blocked by STP)
port 25
IGMP snooping > Example
port 26
Rapier 24i
Switch 3:
port 25
Snooper
port 3
Client 2
igmp-snooper.eps