loss of DHCP traffic on VMs?

Scott Wedekind swedekind at bluecatnetworks.com
Fri Mar 28 17:38:55 UTC 2014

Any chance that you have an AV scanner (that inspects network packets) installed on the DHCP server VM?  That's a characteristic of a memory leak in the scanner's network driver.   Unfortunately, temporarily disabling the AV scanner won't be sufficient, as the driver will remain resident.  To verify, uninstall it for a while and see if the problem goes away.  You can always use a different AV vendor until they get it sorted out if that's the culprit.

For your specific question, no, I've never heard of that problem, and my organization puts out a lot of virtual ISC based DHCP servers on ESX.  It doesn't mean it's not happening, but I'd exhaust other avenues first.

Scott Wedekind

-----Original Message-----
From: dhcp-users-bounces+swedekind=bluecatnetworks.com at lists.isc.org [mailto:dhcp-users-bounces+swedekind=bluecatnetworks.com at lists.isc.org] On Behalf Of Joseph Bernard
Sent: Friday, March 28, 2014 12:23 PM
To: Users of ISC DHCP
Subject: loss of DHCP traffic on VMs?

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?

Joseph B.

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