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NAME

pim

 - Protocol Independent Multicast


 

SYNOPSIS

   #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-SM is a multicast routing protocol that can use the underlying unicast 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 Sx SYNOPSIS about the kernel configuration options), and must run a PIM-SM or PIM-DM capable user-level process. From developer's point of view, the programming guide described in the Sx Programming Guide section should be used to control the PIM processing in the kernel.  

Programming Guide

/* 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-Register 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

STANDARDS

AUTHORS

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

Index

NAME

SYNOPSIS

DESCRIPTION

Programming Guide

SEE ALSO

STANDARDS

AUTHORS

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