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So it looks like the UDP packet loss is due to a difference in the way virtual NICs buffer vs physical NICs. I am testing a physical NIC connected to a VM using DirectPath I/O and can run it to 300Mbps before any noticeable packet loss. I see the same amount
of packet loss at 60Mbps on a virtual NIC. If I increase the TCP socket buffer size greater than the default, I can run either at 900Mbps with no packet loss. Now I just have to find the magic setting that fixes the difference.
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<div>We don't generate 60Mbps of DHCP traffic, so our problem is most like a different issue, but fixing the UDP packet loss couldn't hurt.</div>
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<div>Thanks,</div>
<div>Joseph B.
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<div>On Mar 28, 2014, at 3:26 PM, Joseph Bernard <<a href="mailto:JHB@clemson.edu">JHB@clemson.edu</a>> wrote:</div>
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<div class="moz-cite-prefix">I didn't even realize that was an option. I will try to see if that solves our problem.</div>
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<div class="moz-cite-prefix">Thanks!</div>
<div class="moz-cite-prefix">Joseph B.</div>
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<div>On Mar 28, 2014, at 1:39 PM, Steve Clark <<a href="mailto:sclark@netwolves.com">sclark@netwolves.com</a>></div>
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<div class="moz-cite-prefix">On 03/28/2014 01:23 PM, Joseph Bernard wrote:<br>
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<pre wrap="">We had an issue with DHCP yesterday which lead me to test UDP traffic from the VM we loaded on our VMware ESXi box. I found that after around 25Mbps UDP starts to lose packets, and it gets worse and worse the fast you go. I tried every virtual card type (e1000, VMXNET2, VMXNET3) with the same results. I even tried on different servers, and they were also showing UDP packet loss. Physical boxes on the same network showed no packet loss until I pushed their NICs to the limit (1Gbps).
Has anyone faced DCHP problems by using a VM because of this? If so, were you able to fix it or did you just move back to a physical box?
Thanks,
Joseph B.
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Did you dedicate a nic to the virtual machine or are going thru a vswitch. We got dramatically better results by taking the nic out<br>
of the vswitch dedicating it to the virtual machine. This was in a packet capture environment.<br>
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<div class="moz-signature">-- <br>
Stephen Clark<br>
<b>NetWolves Managed Services, LLC.</b><br>
Director of Technology<br>
Phone: 813-579-3200<br>
Fax: 813-882-0209<br>
Email: <a class="moz-txt-link-abbreviated" href="mailto:steve.clark@netwolves.com">steve.clark@netwolves.com</a><br>
<a class="moz-txt-link-freetext" href="http://www.netwolves.com/">http://www.netwolves.com</a><br>
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