title: Inconsistent packet delivery by NIC, NIC performance measurement
body: <p>One of our customers experiences problem with our streaming application (win32). It seems like UDP (RTP) packets that should be sent by the application with some constant interval (say 20 ms) are actually sent with a greatly variable deltas (say 15ms - 25ms  - 10ms - 30 ms). This is the only customer that experiences the problem so network card or other OS network related infrastructure is our primal suspect.</p>
  
  <p>The question is what kind of network configuration may introduce such problem (AV?,QOS?)</p>
  
  <p>And how can I measure the time between actually calling "send" function and the moment the packet was actually delivered to the network? Is there any tool available for it.</p>