1-11 MLD Snooping ConfigurationWhen configuring MLD Snooping, go to these sections for information you are interested in:z MLD Snooping Overviewz MLD Snooping Configuration Task Listz Displaying and Maintaining MLD Snoopingz MLD Snooping Configuration Examplesz Troubleshooting MLD SnoopingMLD Snooping OverviewMulticast Listener Discovery Snooping (MLD Snooping) is an IPv6 multicast constraining mechanismthat runs on Layer 2 devices to manage and control IPv6 multicast groups.Introduction to MLD SnoopingBy analyzing received MLD messages, a Layer 2 device running MLD Snooping establishes mappingsbetween ports and multicast MAC addresses and forwards IPv6 multicast data based on thesemappings.As shown in Figure 1-1, when MLD Snooping is not running, IPv6 multicast packets are broadcast to alldevices at Layer 2. When MLD Snooping runs, multicast packets for known IPv6 multicast groups aremulticast to the receivers at Layer 2.Figure 1-1 Before and after MLD Snooping is enabled on the Layer 2 deviceIPv6 multicast packet transmissionwithout MLD SnoopingSourceMulticast routerHost AReceiverHost BHost CReceiverIPv6 multicast packetsLayer 2 switchIPv6 multicast packet transmissionwhen MLD Snooping runsSourceMulticast routerHost AReceiverHost BHost CReceiverLayer 2 switchMLD Snooping forwards multicast data to only the receivers requiring it at Layer 2. It brings the followingadvantages:
