Multicast Listener Discovery

Multicast Listener Discovery (MLD) is a component of the Internet Protocol Version 6 (IPv6) suite. MLD is used by IPv6 routers for discovering multicast listeners on a directly attached link, much like Internet Group Management Protocol (IGMP) is used in IPv4. The protocol is embedded in ICMPv6 instead of using a separate protocol. MLDv1 is similar to IGMPv2^[1] and MLDv2 similar to IGMPv3.^[2]

Protocol

The following ICMPv6 message types are used:

ICMPv6 message type values^[2]

Message	Type value
Multicast Listener Query	130
MLDv1 Multicast Listener Report	131
MLDv2 Multicast Listener Report	143
Multicast Listener Done	132

Support

Several operating systems support MLDv2:

• Windows Vista and later^[3]
• FreeBSD since release 8.0^[4]
• The Linux kernel since 2.5.68^[5]
• macOS^[6]