H3C Technologies H3C S3100V2 Series Switches - Manual (Page 66)

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MLD snooping configuration(available only on
the S3100V2-EI)
This chapter includes these sections:
• MLD snooping overview
• MLD snooping configuration task list
• Displaying and maintaining MLD snooping
• MLD snooping configuration examples
• Troubleshooting MLD snooping
MLD snooping overview
Multicast Listener Discovery (MLD) snooping is an IPv6 multicast constraining mechanism that runs on
Layer 2 switches to manage and control IPv6 multicast groups.
Introduction to MLD snooping
By analyzing received MLD messages, a Layer 2 switch that is running MLD snooping establishes
mappings between ports and multicast MAC addresses and forwards IPv6 multicast data based on these
mappings.
As shown in
Figure 21 , when MLD snooping is not running, IPv6 multicast packets are broadcast to all
devices at Layer 2. When MLD snooping runs, multicast packets for known IPv6 multicast groups are
multicast to the receivers at Layer 2.
Figure 21 Before and after MLD snooping is enabled on the Layer 2 switch
IPv6 multicast packet transmission
without MLD Snooping
Source
Multicast router
Host A
Receiver
Host B
Host C
Receiver
IPv6 multicast packets
Layer 2 switch
IPv6 multicast packet transmission
when MLD Snooping runs
Source
Multicast router
Host A
Receiver
Host B
Host C
Receiver
Layer 2 switch