The USB Native Driver Fling, a popular ESXi driver by Songtao Zheng and William Lam that adds support for USB-based Network Adapters, has been updated to version 1.6. The new version has added support for RTL8156 based 2.5GBASE-T network adapters.
Multi-Gigabit network adapters with 5GBASE-T are available for a while, but those 5GbE adapters cost about $100 USD. The new driver allows the usage of 2.5GbE adapters that are available for as low as $25 USD. The driver was released yesterday, and luckily I already own a bunch of 2.5GbE adapters, so I could give it a test drive immediately.
Installation / Update
The installation or update is very simple. Just download the driver for your ESXi version (available for ESXi 7.0, 6.7, and 6.5) from VMware Flings, run the following command and reboot your ESXi Host.
# esxcli software vib install -d /path/ESXi700-VMKUSB-NIC-FLING-39035884-component-16770668.zip
If you are running ESXi 7.0, you can also use the new component feature:
# esxcli software component apply -d /path/ESXi700-VMKUSB-NIC-FLING-39035884-component-16770668.zip
There is nothing to consider when you have an older driver. Just install the new driver. You can also install the driver without being in maintenance mode, but you have to reboot it afterward.
Which 2.5GBASE-T should you get for ESXi?
Be careful when buying 2.5GbE adapters. Only adapters with RTL8156 chip, VID: 0BDA, and PID: 8156 are supported. There are adapters that do not work with the driver at the moment. Unfortunately, you usually don't find that information in the specifications of the adapter.
I highly recommend the CableCreation CD0673 2.5GBASE-T adapter, which is currently available for about $25 USD. It's cheap and known to work.
|CableCreation CD0673||Type A||0BDA||8156||$25 USD||YES|
|TRENDnet TUC-ET2G||Type C||20F4||E02B||$40 USD||NO|
|CLUB 3D CAC-1420||Type A||0BDA||8156||$45 USD||YES|
|Digitus DN-3025||Type C||????||????||$45 USD||?|
|Asustor AS-U2.5G||Type C||????||????||$46 USD||?|
|Manhattan 153300||Type C||????||????||$50 USD||?|
|Cable Matters 201090-N||Type C||0BDA||8156||$50 USD||YES|
|StarTech US2GC30||Type C||????||????||$80 USD||?|
If you have any of the adapters mentioned above, please comment to confirm if they are working.
Do you need a special cable for 2.5GBASE-T?
You do not need special cables for 2.5/5GBASE-T. The NBASE-T specification was created to work with Category 5e cables, which is the lowest standard for Gigabit networks. Only for long cables (>50m) you might get problems with alien near-end crosstalk (NEXT) and alien far-end crosstalk (FEXT). Those problems can be mitigated with CAT6 or CAT6a cables.
I've done a basic performance test using two CableCreation CD0673 2.5GBASE-T adapters, directly connected with an CAT5e cable. With iperf3 running on the ESXi I achieved 2.34 Gbit/sec over 5 Minutes.
Latency using ping: round-trip min/avg/max = 0.535/0.608/0.707 ms
The CableCreation CD0673 2.5GBASE-T adapter I'm using works with MTU 9000. When changing the MTU, always check that the MTU has been correctly applied. As a reminder, you set the MTU size at vSwitch level and when the adapter does not support jumbo frames, it will silently fail. (vmkernel.log: vmkusb: Set MTU 9000 is not supported: Failure).
Switch options with Multi-Gigabit support
When you want to connect more than 2 systems you need a Multi-Gigabit capable network switch. As this technology is not very common, there are only a few options available at the moment.
MikroTik CRS305-1G-4S+IN ($130 USD)
4 Port switch with 2.5GBASE-T and 5GBASE-T support. Ports are in SFP format, so you additionally need an SFP (MikroTik S+RJ10) which costs $60 USD per port. The switch also supports 10GbE SFPs.
= $92.5 USD per 2.5GBASE-T port
Netgear MS510TX ($260 USD)
10 Port Switch with 5 ports that do support 2.5GBASE-T. 2 of them also support 5GBASE-T and one port also supports 10GBASE-T. The other 4 ports are 1GbE only and it has one 10GbE SFP Port.
= $52 USD per 2.5GBASE-T port
TRENDnet TEG-30102WS ($450 USD)
10 Port 2.5GBASE-T Switch. This switch does not support 5GBASE-T.
= $45 USD per 2.5GBASE-T port