Configuring Igmp Snooping; Overview; Basic Igmp Snooping Concepts - HP 1920 Gigabit Ethernet Switch Series User Manual

Configuring IGMP snooping

Overview

IGMP snooping runs on a Layer 2 switch as a multicast constraining mechanism to improve multicast
forwarding efficiency. It creates Layer 2 multicast forwarding entries from IGMP packets that are
exchanged between the hosts and the router.
As shown in
to all hosts. When IGMP snooping is enabled, the Layer 2 switch forwards multicast packets of known
multicast groups to only the receivers of the multicast groups.
Figure 227 Multicast forwarding before and after IGMP snooping is enabled

Basic IGMP snooping concepts

This section lists the basic IGMP snooping concepts.
IGMP snooping related ports
As shown in
in a multicast group.
Figure 227, when IGMP snooping is not enabled, the Layer 2 switch floods multicast packets
Figure 228, IGMP snooping runs on Switch A and Switch B, Host A and Host C are receivers
252