24-Port Layer 3 Switch Management Guide

C ONFIGURING THE S WITCH
3-144
CLI – This example assigns a multicast address to VLAN 1, and then
displays all the known multicast services supported on VLAN 1.
Layer 3 IGMP (Query used with Multicast Routing)
IGMP Snooping – IGMP Snooping is a Layer 2 function (page 3-137) that
can be used to provide multicast filtering when no other switches in the
network support multicast routing. (Note that IGMP Snooping can only
be globally enabled.)
IGMP Query – Multicast query is used to poll each known multicast group
for active members, and dynamically configure the switch ports which
need to forward multicast traffic. Although the implementation differs
slightly, IGMP Query is used in conjunction with both Layer 2 IGMP
Snooping and multicast routing. Note that when using IGMP Snooping,
multicast query is automatically enabled. (See “Configuring IGMP
Snooping Parameters” on page 3-137.)
Layer 3 IGMP – This protocol includes a
form of multicast query specifically designed
to work with multicast routing. A router
periodically asks its hosts if they want to
receive multicast traffic. It then propagates
service requests on to any upstream multicast
router to ensure that it will continue to receive the multicast service. Layer
3 IGMP can be enabled for individual VLAN interfaces (page 3-144).
(Note that Layer 2 snooping and query is disabled if Layer 3 IGMP is
enabled.)
Console(config)#ip igmp snooping vlan 1 static 224.1.1.12
ethernet 1/12 4-197
Console(config)#exit
Console#show mac-address-table multicast vlan 1 4-200
VLAN M'cast IP addr. Member ports Type
---- --------------- ------------ -------
1 224.1.1.12 Eth1/12 USER
1 224.1.2.3 Eth1/12 IGMP
Console#
L3 - network core
multicast routing
and L3 IGMP query
( (