H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 48)

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Configuring MLD snooping
MLD snooping overview
Multicast Listener Discovery (MLD) snooping is an IPv6 multicast constraining mechanism that runs on
Layer 2 devices to manage and control IPv6 multicast groups.
By analyzing received MLD messages, an MLD snooping–enabled access controller establishes
mappings between ports and multicast MAC addresses and forwards IPv6 multicast data based on these
mappings.
As shown in
Figure 9 , when MLD snooping is not running, IPv6 multicast packets are flooded to all
wireless clients. When MLD snooping runs, multicast packets for known IPv6 multicast groups are
multicast to specific wireless clients at Layer 2. This feature improves bandwidth efficiency, enhances
multicast security, and helps per-host accounting for multicast users.
Figure 9 Before and after MLD snooping is enabled on the AC
Basic concepts in MLD snooping
MLD snooping related ports
As shown in Figure 10 , Router A connects to the multicast source, MLD snooping runs on Device A and
Device B, and Host A and Host C are receiver hosts (IPv6 multicast group members).
Source
Client A
Receiver
Client B
Client C
Receiver
AP
Source
Client A
Receiver
Client B
Client C
Receiver
AP WLAN-DBSS
66:18
WLAN-DBSS
67:19
WLAN-DBSS
68:20
AC
IP network
AC
IP network
IPv6 multicast packet transmission
without MLD Snooping
IPv6 multicast packet transmission
when MLD Snooping runs
IPv6 multicast packets
WLAN-DBSS
66:18
WLAN-DBSS
67:19
WLAN-DBSS
68:20