A multicast server can be written badly as follows:

$bc_string = "Hello World!";
$sock = socket_create(AF_INET, SOCK_DGRAM, 0); 
$opt_ret = socket_set_option($sock, 1, 6, TRUE);
$send_ret = socket_sendto($sock, $bc_string, strlen($bc_string), 0, '230.0.0.1', 4446);

Checking the return types is needed, but this does allow for you to multicast from php code.