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]

References

1. S. Deering; W. Fenner; B. Haberman (October 1999). Multicast Listener Discovery (MLD) for IPv6. Network Working Group. doi:10.17487/RFC2710. RFC 2710. Proposed Standard. Updated by RFC 3590 and 3810.
2. R. Vida; L. Costa, eds. (June 2004). Multicast Listener Discovery Version 2 (MLDv2) for IPv6. Network Working Group. doi:10.17487/RFC3810. RFC 3810. Proposed Standard. Updates RFC 2710. Updated by RFC 4604.
3. "MLD and IGMP Using Windows Sockets". Windows Sockets 2. 2011-09-16.
4. "mld(4): Multicast Listener Discovery Protocol". FreeBSD Kernel Interfaces Manual. 2009-05-27.
5. Torvalds, Linus (2003-04-19). "Linux 2.5.68 ChangeLog".
6. IPv6Hardening Guide for OS-X (PDF), 2015-01-29, retrieved 2021-05-23