As part of upgrading my personal vSphere home lab from an Apple Mac Mini to an Intel NUC (more on this in a future blog), I have been researching to see if there are other alternatives for adding an additional network adapter. The Intel NUC only includes a single built-in ethernet adapter which is similar to the Mac Mini. However, the NUC also lacks additional IO connectors like a Thunderbolt port which the Mac Mini includes and can support a Thunderbolt to Ethernet adapter. I think this is probably the only downside to the Intel NUC platform which has been similar feedback that I have seen from other vSphere home labbers who currently use or would like to use the NUC. Perhaps, with the next update of the NUC platform code named "Skull Canyon", the rumored Thunderbolt 3 / USB-c connector may make things easier as some of the existing vendors who produce Thunderbolt to ethernet adapter also use common drivers like the Broadcom tg3 which have historically worked with ESXi.

One option that has been suggested by many folks over the years was to see if a USB based ethernet adapter could be used to provide additional networking to ESXi? Historically, the answer had been no because there were no known device drivers that would work with ESXi. I had even looked into this a few years ago and although I ran into some folks who seemed to have made it work, I was never able to find the right USB ethernet adapter to personally confirm myself. It was only until last week, I decided to start fresh again and after a bit of Googling I came across an old VMTN thread here where VMTN user AK_____28 mentioned he had success with the StarTech USB 3.0 to Gigabit Ethernet NIC Network Adapter and using a custom compiled driver that was posted over here by another user named Trickstarter.

UPDATE (02/12/19) - A new VMware Native Driver for USB-based NICs has just been released for ESXi 6.5/6.7, please use this driver going forward. If you are still on ESXi 5.5/6.0, you can continue using the existing driver but please note there will be no additional development in the existing vmklinux-based driver.

UPDATE (03/29/16) - Please have a look at this updated article here which includes ESXi 5.5 and 6.0 driver.

Disclaimer: In case it is not clear and apparent, you should never install any unknown 3rd party software on your ESXi host as it can potentially lead to instability issues or worse open yourself to a security hole. The following solution is not officially supported by VMware, please use at your own risk.

I decided to bite the bullet and give this solution a try and purchased the USB ethernet adapter from Amazon here.



There are two modules that needs to be downloaded, extracted and loaded onto ESXi. I have included the links below for your convenience:

As the VMTN thread mentioned, you can load using either the vmkload_mod or ESXCLI. Here are the two commands that I used in the following order:

vmkload_mod /vmfs/volumes/mini-local-datastore-1/usbnetvz026

vmkload_mod /vmfs/volumes/mini-local-datastore-1/ax88179vz026

When I tried to initially load either of the modules, I would always get the following error:

vmkwarning.log:2016-02-28T21:54:54.531Z cpu6:374787)WARNING: Elf: 2041: Load of <usbnetvz026> failed : missing required namespace <com.vmware.usb#9.2.1.0>

As you can imagine, I was pretty bummed to see this since I was afraid that something like this would happen. I was not sure if the device I had purchased no longer worked or if was the drivers? I saw that these modules were initially compiled for ESXi 5.1 (at the time, that was the latest version) and the only difference was that I was using a much newer version of ESXi, specifically 6.0 Update 1. I decided to install the latest version of ESXi 5.1 Update 3 and tried the process again and to my surprise, the modules loaded without errors. I suspect that this was a hard dependency on the namespace version which was version 9.2.1.0 and the latest version is now 9.2.3.0.



After successfully loading the two modules, I ran the following command:

esxcfg-nics -l

to verify that ESXi did in fact did claim the USB ethernet device and as you can see from the screenshot below, it did indeed!



Next up, I needed to verify basic connectivity and added the new uplink to my existing vSwitch. You must use the following ESXCLI command (esxcfg-vswitch command does not work apparently for non vmnicX devices)

esxcli network vswitch standard uplink add -u vusb0 -v vSwitch0

Once added, I hopped over to the vSphere C# Client to see if the device is now showing up under the Network Adapters tab, which it is.



Finally, the last test was to make the vsb0 (this is how ESXi names the device) device the active connection while moving my existing vmnic0 to stand-by. Networking connectivity continued to function and I was even able to transfer an ISO image over the USB ethernet adapter without any issues.



So it looks like it is possible to get a USB based ethernet adapter to function with ESXi, at least with the specific model listed above (PCI ID 0b95:1790). The challenge now is to see if there is a way to build an updated version of the drivers targeted at the latest ESXi 6.0 release. From what I have been able to follow on the forum here, it looks like there was also some amount of non-trivial code changes that were required to get the driver to function. If true, without those changes, it can difficult to re-compile the driver. I have reached out to the original author to see if he might be able to share the changes he made to the driver code. In the mean time, if folks are interested in giving the build process a try, Trickstarter did a great two part write up on how to setup your build environment and compile an example driver.

Although the write up is targeted at ESXi 5.x, you can download the equilvenet packages for ESXi 6.0 which includes the ESXi Open Source Disclosure Package as well as the VMware Toolchain which is required and used to compile the source code. I have provided the direct download links below.

You can also find the latest version of the USB ethernet adapter ax88179 ASIX driver here. I have also attempted to compile just the driver but have already ran into some issues. I have not had time to dig further, so not sure how far I will be able to get. Any tips or tricks others may have for compiling against ESXi 6.0, feel free to share them and I will give them a shot when I get some time!