We are concept testing multicasting for its reliability. However,
using some POSIX examples, we have not been able to get it working. We
suspect it may be a QNX configuration problem. Here is what we have done

1.) Added the -M argument to the Dev.ether1000 driver at startup
2.) Upgraded to TCP/IP (Beta 5) (supports multicasting)
2.) Used the following block of code to attempt a send of multicast

int gSocket, result;
char *message=“Hello World!\n”;
struct sockaddr_in addr;
struct ip_mreq mreq;

// create socket
gSocket = socket(AF_INET, SOCK_DGRAM, 0);
if (gSocket<0) {
perror(“Can’t create socket”);

// set up destination address
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = inet_addr(HELLO_GROUP);
addr.sin_port = htons(HELLO_PORT);

// send to our destination
while (!kbhit()) {
result = sendto(gSocket, message, sizeof(message), 0,
(struct sockaddr *)&addr, sizeof(addr));
if (result<0) {
perror(“Cannot send multicast packet”);
sleep (1);

…However, we receive an error … “Cannot route to host”

Any advice?

Fitzgerald, SEA, Inc.