Multicast Join on Linux and IGMPv3

[rtv@myhost]$ sudo /usr/sbin/tcpdump -i eth1.22 igmp
tcpdump: listening on eth1.22
00:20:09.007094 switch-a.stage > ALL-SYSTEMS.MCAST.NET: igmp query v2 [max resp time 20] [ttl 1]
00:20:09.241946 10.129.22.236 > 232.0.1.10: igmp v2 report 232.0.1.10 (DF) [tos 0xc0]  [ttl 1]
00:20:10.472159 10.129.22.236 > 236.0.1.101: igmp v2 report 236.0.1.101 (DF) [tos 0xc0]  [ttl 1]

44 packets received by filter

... joinMulticast(in_addr mcast_addr, in_addr interface_addr)
{
  struct ip_mreq  mcast_req;

  mcast_req.imr_multiaddr.s_addr = mcast_addr;
  mcast_req.imr_interface.s_addr = interface_addr;
  int err = setsockopt(fFileDesc, IPPROTO_IP, IP_ADD_MEMBERSHIP,
    (char*)&theMulti, sizeof(theMulti));
  // handle errors etc.
  // ...
}