Overview

MLD snooping runs on a Layer 2 switch as an IPv6 multicast constraining mechanism to improve multicast forwarding efficiency. It creates Layer 2 multicast forwarding entries from MLD messages that are exchanged between the hosts and the router.

As shown in Figure 42, when MLD snooping is not enabled, the Layer 2 switch floods IPv6 multicast packets to all hosts. When MLD snooping is enabled, the Layer 2 switch forwards multicast packets of known IPv6 multicast groups to only the receivers.