Created a new vSwitch with no physical network adapters and no VLAN tags assigned to it. Left it at 120 ports as default, labelled it "Private Network".
Added a "Flexible" network adapter to each Ubuntu 10.x LTS (32-bit) machine (they were migrated from an older ESXi 4.0 host) with this new "Private Network" label assigned as secondary NICs on both virtual machines; put them both on the same subnet once they booted back up.
iperf with the default TCP settings,
-b 10M for size.
Getting a very consistent 50.6Mbps. Seems kind of lackluster for a network that should exist in memory on the host, should it not?
I thought so too, so I tried two other VMs on the same host, but these were created with ESXi 5 (VM version 8), so I used the VMXNET 3 and was getting (likely inaccurately) 34Gbps (!).
Did a quick rsync (over SSH) of a 1GB file and was getting a very nice 20.4MB/s (163.2 Mbps).
Is it the VM version or the VMXNET 3 vs. Flexible here?