I have an ESXi 6.0 host on which I experience very weird networking performance. When I download a 1000mb .bin file using wget, the speed is fine for the first ±4 seconds: 14MB/s. This is the maximum speed of my ISP. After those first seconds the speed drops to approximately 5MB/s, and sometimes even further.
I have configured a virtual switch, which is connected to my NIC: a HP 380t which is supported by ESXi. I also tried injecting the drivers for my onboard Realtek, but this gives me the same results. I tried all three available virtual NICS: vmxnet 2 and 3, and the e1000. The latest VMWare tools are installed. MTU's are all default for now: 1500.
I tried multiple VM's:
- Ubuntu 14.04
- Ubuntu 12.04
- CentOS 7
- Debian 8.2
These VM's are installed on a somewhat older SSD. I benchmarked it using hdparm, and got 123MB/s.
Other things I have tried are disabling the firewall (ufw in Ubuntu), and disabling IPv6, all to no avail.
I run the host on a Asus M5A97 R2.0 with a FX-6300 and 16GB of ECC RAM. If I need to run any other benchmarks to find out why this problem occurs, I'm happy to help.