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Configuring MLD snooping
Overview
MLD snooping runs on a Layer 2 device 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
, when MLD snooping is not enabled, the Layer 2 switch floods IPv6 multicast
packets to all hosts in a VLAN or VSI. When MLD snooping is enabled, the Layer 2 switch forwards
multicast packets of known IPv6 multicast groups to only the receivers.
Figure 65 Multicast packet transmission processes without and with MLD snooping
MLD snooping ports
As shown in
, MLD snooping runs on Switch A and Switch B, and Host A and Host C are
receiver hosts in an IPv6 multicast group. MLD snooping ports are divided into member ports and
router ports.
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