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 multicast 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 processing Group-and-Source Specific
               Queries (GSR).  As GSR query processing requires maintaining state on  the  host,  it  may  cause
               memory  to  be  allocated, and is therefore a potential attack point for Denial-of-Service (DoS).
               If more than one GSR query is received within this threshold, it will be dropped, to mitigate the
               potential 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 compatibility will be enabled until the v1 'Older Version Querier
               Present' timer expires.  This sysctl is normally enabled by default.

SEE ALSO

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

HISTORY

       The mld manual page appeared in FreeBSD 8.0.

Debian                                            April 8, 2013                                           MLD(4)