Hello everyone,
We are currently working with 8 Server 2012 R2 Data Center servers which are virtualized on a vmware cluster of 2 host servers with a public and a private network. In vmware, a vSwitch attached to physical NIC #1 represents the Public interface which connects to all of the virtual machines using their respective NIC #1. A second vSwitch is attached to physical NIC #2 and represents the Private network which is connected to all of the virtual machines on their respective NIC #2.
To keep this simple we will explain the behavior of 2 VMs. Web01 and Web02. They are both configured as described above and both reside on the same host server. That is to be said that no traffic is passing onto the physical network, but only traversing the vSwitch.
Web01 = Pub IP: x.x.x.1, Priv IP 192.168.1.1
Web02 = Pub IP: x.x.x.2, Priv IP 192.168.1.2
At the console of Web01, we map a drive from Web01 to Web02 @ \\192.168.1.2\c$
We then proceed to transfer a 5GB test file created using fsutil across the network share. While doing this we watch the Network graphs from the Resource monitor and notice that the traffic is passing on both the public and the private simultaneously. Though, we are not able to tell if this is mirrored data, a reporting error or a true split in traffic.
I've recorded the following video to show exactly what is happening: http://youtu.be/vVXyz5i1ViU
There is no NIC teaming going on, the servers are using the Vmxnet3 VMWare driver which is recommended for Server 2012, and this behavior does not happen when Windows 2008 is involved. Additionally, we have tested this on physical hardware, and are seeing similar results.
Has anyone seen this behavior and if so, what is it called? Can it be disabled? Any other information or thoughts on why these servers are passing traffic on both the public interface and the private interface at the same time, would be extremely helpful.
If I have left out any pertinent information, please let me know and I will provide it.
Thank you in advance!