Missing multicast messages in Windows 2008 R2

Question

I've got a couple of applications sending multicast messages over several channels. Most channels publish several thousand messages / second. The channel I'm having issues with (though it probably affects the others, too) publishes about 8k messages at the top of every minute. Most of the time, all the messages arrive. Sometimes, some or many are missing at the application layer, but Wireshark captures them (ruling out networking/sending issues). I don't believe it's the application for two reasons: 1) I've got two completely independent applications running, one written in C++, the other in C#, with no shared code. Both applications always receive/miss the same # of messages. 2) Those same two applications, when they run on the same server that's publishing, do not miss any messages. So something seems amiss between the NIC and the application, ie the OS. Network and CPU utilization are negligible (~5%).

We've applied the patch described here, http://support.microsoft.com/kb/2639824 , with no success.

Any thoughts would be greatly appreciated.

Answer 1

After further study, the solution has been found. First, I discovered that one of my assumptions (that Wireshark was seeing the packets and my app wasn't) turned out to be false. Since Wireshark was also missing the packets, the problem must exist upstream, starting at the NIC. After disabling Interrupt Moderation on the NIC, the problem was solved.