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PIM(4)			    Kernel Interfaces Manual			PIM(4)

NAME
       pim -- Protocol Independent Multicast

SYNOPSIS
       options MROUTING

       #include	<sys/types.h>
       #include	<sys/socket.h>
       #include	<netinet/in.h>
       #include	<netinet/ip_mroute.h>
       #include	<netinet/pim.h>

       int
       getsockopt(int	  s,	 IPPROTO_IP,	 MRT_PIM,     void    *optval,
	     socklen_t *optlen);

       int
       setsockopt(int	s,   IPPROTO_IP,   MRT_PIM,   const   void    *optval,
	     socklen_t optlen);

       int
       getsockopt(int	  s,	IPPROTO_IPV6,	 MRT6_PIM,    void    *optval,
	     socklen_t *optlen);

       int
       setsockopt(int  s,  IPPROTO_IPV6,   MRT6_PIM,   const   void   *optval,
	     socklen_t optlen);

DESCRIPTION
       PIM  is	the  common name for two multicast routing protocols: Protocol
       Independent Multicast - Sparse Mode (PIM-SM) and	 Protocol  Independent
       Multicast - Dense Mode (PIM-DM).

       PIM-SM is a multicast routing protocol that can use the underlying uni-
       cast  routing  information base or a separate multicast-capable routing
       information base.  It builds unidirectional shared trees	 rooted	 at  a
       Rendezvous  Point  (RP) per group, and optionally creates shortest-path
       trees per source.

       PIM-DM is a multicast routing protocol that uses	the underlying unicast
       routing information base	to flood multicast datagrams to	all  multicast
       routers.	  Prune	 messages  are	used  to prevent future	datagrams from
       propagating to routers with no group membership information.

       Both PIM-SM and PIM-DM are fairly complex protocols, though  PIM-SM  is
       much  more  complex.  To	enable PIM-SM or PIM-DM	multicast routing in a
       router, the user	must enable multicast routing and  PIM	processing  in
       the kernel (see "SYNOPSIS" about	the kernel configuration options), and
       must  run  a  PIM-SM or PIM-DM capable user-level process.  From	devel-
       oper's  point  of  view,	 the  programming  guide  described   in   the
       "Programming  Guide" section should be used to control the PIM process-
       ing in the kernel.

   Programming Guide
       After a multicast routing socket	is open	and  multicast	forwarding  is
       enabled	in  the	kernel (see multicast(4)), one of the following	socket
       options should be used to enable	or disable PIM processing in the  ker-
       nel.   Note  that  those	 options require certain privilege (i.e., root
       privilege):

       /* IPv4 */
       int v = 1;	 /* 1 to enable, or 0 to disable */
       setsockopt(mrouter_s4, IPPROTO_IP, MRT_PIM, (void *)&v, sizeof(v));

       /* IPv6 */
       int v = 1;	 /* 1 to enable, or 0 to disable */
       setsockopt(mrouter_s6, IPPROTO_IPV6, MRT6_PIM, (void *)&v, sizeof(v));

       After PIM  processing  is  enabled,  the	 multicast-capable  interfaces
       should  be added	(see multicast(4)).  In	case of	PIM-SM,	the PIM-Regis-
       ter virtual interface must be added as well.  This can be  accomplished
       by using	the following options:

       /* IPv4 */
       struct vifctl vc;
       memset(&vc, 0, sizeof(vc));
       /* Assign all vifctl fields as appropriate */
       ...
       if (is_pim_register_vif)
	   vc.vifc_flags |= VIFF_REGISTER;
       setsockopt(mrouter_s4, IPPROTO_IP, MRT_ADD_VIF, (void *)&vc,
		  sizeof(vc));

       /* IPv6 */
       struct mif6ctl mc;
       memset(&mc, 0, sizeof(mc));
       /* Assign all mif6ctl fields as appropriate */
       ...
       if (is_pim_register_vif)
	   mc.mif6c_flags |= MIFF_REGISTER;
       setsockopt(mrouter_s6, IPPROTO_IPV6, MRT6_ADD_MIF, (void	*)&mc,
		  sizeof(mc));

       Sending	or  receiving  of  PIM	packets	can be accomplished by opening
       first  a	 "raw  socket"	(see  socket(2)),  with	 protocol   value   of
       IPPROTO_PIM:

       /* IPv4 */
       int pim_s4;
       pim_s4 =	socket(AF_INET,	SOCK_RAW, IPPROTO_PIM);

       /* IPv6 */
       int pim_s6;
       pim_s6 =	socket(AF_INET6, SOCK_RAW, IPPROTO_PIM);

       Then,  the  following  system  calls can	be used	to send	or receive PIM
       packets:	sendto(2), sendmsg(2), recvfrom(2), recvmsg(2).

SEE ALSO
       getsockopt(2),	recvfrom(2),   recvmsg(2),   sendmsg(2),    sendto(2),
       setsockopt(2), socket(2), inet(4), intro(4), ip(4), multicast(4)

STANDARDS
       The  PIM-SM  protocol  is  specified  in	 RFC  2362  (to	be replaced by
       draft-ietf-pim-sm-v2-new-*).   The  PIM-DM  protocol  is	 specified  in
       draft-ietf-pim-dm-new-v2-*).

AUTHORS
       The  original IPv4 PIM kernel support for IRIX and SunOS-4.x was	imple-
       mented by Ahmed Helmy (USC and SGI).  Later the code was	ported to var-
       ious BSD	flavors	and modified by	 George	 Edmond	 Eddy  (Rusty)	(ISI),
       Hitoshi	Asaeda	(WIDE  Project),  and  Pavlin  Radoslavov (USC/ISI and
       ICSI).  The IPv6	PIM kernel support was implemented by the KAME project
       (https://www.kame.net), and was based on	the IPv4 PIM kernel support.

       This manual page	was written by Pavlin Radoslavov (ICSI).

FreeBSD	14.3		       February	12, 2007			PIM(4)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=pim&sektion=4&manpath=FreeBSD+14.3-RELEASE+and+Ports>

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