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MLD(4)			     Kernel Interfaces Manual			  MLD(4)

NAME
     mld -- Multicast Listener Discovery Protocol

SYNOPSIS
     #include <sys/types.h>
     #include <sys/socket.h>
     #include <netinet/in.h>
     #include <netinet/in_systm.h>
     #include <netinet/ip6.h>
     #include <netinet/icmp6.h>
     #include <netinet6/mld6.h>

     int
     socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);

DESCRIPTION
     MLD is a control plane protocol used by IPv6 hosts and routers to propagate
     multicast group membership information.  Normally this protocol is not used
     directly,	except by the kernel itself, in response to multicast membership
     requests by user applications.  Multicast routing protocol daemons may open
     a raw socket to directly interact with mld and receive membership reports.

     As of FreeBSD 8.0, MLD version 2 is implemented.	This  adds  support  for
     Source-Specific  Multicast  (SSM),  whereby applications may communicate to
     upstream multicast routers that they are only interested in receiving  mul-
     ticast streams from particular sources.  The retransmission of state-change
     reports adds some robustness to the protocol.

SYSCTL VARIABLES
     net.inet6.mld.ifinfo
	     This opaque read-only variable exposes the per-link MLDv2 status to
	     ifmcstat(8).

     net.inet6.mld.gsrdelay
	     This  variable  specifies	the time threshold, in seconds, for pro-
	     cessing Group-and-Source Specific Queries (GSR).  As GSR query pro-
	     cessing requires maintaining state on the host, it may cause memory
	     to be allocated, and is therefore a potential attack point for  De-
	     nial-of-Service  (DoS).   If  more  than  one GSR query is received
	     within this threshold, it will be dropped, to mitigate  the  poten-
	     tial for DoS.

     net.inet6.mld.v1enable
	     If  this  variable  is non-zero, then MLDv1 membership queries (and
	     host reports) will be processed by this host, and backwards compat-
	     ibility will  be  enabled	until  the  v1	'Older	Version  Querier
	     Present'  timer  expires.	 This  sysctl is normally enabled by de-
	     fault.

SEE ALSO
     netstat(1), sourcefilter(3), icmp6(4), inet(4), multicast(4), ifmcstat(8)

HISTORY
     The mld manual page appeared in FreeBSD 8.0.

FreeBSD 15.1			  April 8, 2013 			  MLD(4)
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