Well, that output doesn't show any new (intentional) drops, but the kernel age means there could be an already-fixed bug, too. A couple things I'd suggest: 1) if you can run your program with a unicast address and see if you have similar drops 2) even if you can't update your entire kernel, if you can run the test program on a current kernel (even on a different system), you may get a hint whether it's a problem that has been fixed (figuring out which patch(es) you need is another matter!) 3) if the test program (sender and receiver) is reasonably small, you can post that here and I can try it on a current kernel to see if I can reproduce the results on different hardware, as well as look for any problems in the application. I don't think promiscuous mode directly relates, but tcpdump has an option to run with or without promiscuous mode. So you should be able to look at the packets both ways. But the IP receive count won't go up if there's a problem with device receives (like the multicast filter not matching), and you said when you had drops the packet count was correct, I believe. +-DLS - To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html