There are 2 different types of Network Adapters:
- Para-virtual network devices - E.g. VMXNET devices. VMXNET3 is a generation 3 device.
- Emulated network devices - E.g. E1000, E1000e, VLANCE etc.
The Device drivers for emulated devices are typically shipped as inbox drivers (part of the guest OS) so you don't have to install the device drivers separately. However for using para-virtual devices you need special device drivers which are shipped as part of VMware Tools. If you plan to use para-virtual devices you must install VMware tools. On modern Linux kernels the para-virtual device drivers are also part of the base kernel package.
What is the difference between the 2 types of adapters?
- Emulated devices mimics the behavior of the physical adapter of the type mentioned. Example a E1000 - mimics the behavior of Intel Ethernet E1000 adapter.
- VMXNET3 para-virtual adapter is software adapter and it does not mimic any particular physical adapter. These adapters are only found and supported in a virtualized environment, i.e. they cannot be used in a physical world. They also include some smart features such as support for hardware offloads and shared memory copying etc. These additional features help improve the performance of any para-virtual device. In comparison to an emulated adapter, a para-virtual adapter has a smaller CPU overhead and hence consumes lesser physical CPU resources.
What network adapter to select?
Whenever possible, it is strongly recommended to use para-virtual devices with a virtual machine. When using para-virtual adapters use the latest generation of the para-virtual adapter. Presently it is VMXNET3.
There is an excellent VMware Knowledge Base article from VMware which explains this in more detail. Hope that helps.
Regards / Shekhar
