The possible virtual network adapters include three emulated types, three paravirtualized types, and a hybrid adapter.

The emulated virtual network adapters are:

  • The Vlance virtual network adapter, which emulates an AMD 79C970 PCnet32 NIC. Drivers for this NIC are found in most 32-bit operating systems.

  • The E1000 virtual network adapter, which emulates an Intel 82545EM NIC. Drivers for this NIC are found in many recent operating systems.

  • The E1000E virtual network adapter, which emulates an Intel 82574 NIC. Drivers for this NIC are found in a smaller set of recent operating systems.

The VMXNET family of paravirtualized network adapters provide better performance in most cases than the emulated adapters. These paravirtualized network adapters implement an idealized network interface that passes network traffic between the virtual machine and the physical network interface card with minimal overhead. The VMXNET virtual network adapters (especially VMXNET3) also offer performance features not found in the other virtual network adapters. Drivers for VMXNET-family adapters are available for many guest operating systems supported by VMware Cloud on AWS; for optimal performance these adapters should be used for any guest operating system that supports them.

The VMXNET family of paravirtualized virtual network adapters includes:

  • The VMXNET virtual network adapter. (This adapter is not available in VMware Cloud on AWS; it is included here for context.)

  • The VMXNET2 virtual network adapter (also called “Enhanced VMXNET”). This adapter is based on the VMXNET adapter, but adds a number of performance features.

  • The VMXNET3 virtual network adapter (also called VMXNET Generation 3). This adapter has all the features of the VMXNET2 adapter, along with several new ones.

Lastly, there’s a hybrid virtual network adapter:

  • The Flexible virtual network adapter, which starts out emulating a Vlance adapter, but can function as a VMXNET adapter with the right driver.


The network speeds reported by the guest network driver in the virtual machine do not reflect the actual speed of the underlying physical network interface card. For example, the Vlance guest driver in a virtual machine reports a speed of 10Mb/s because the AMD PCnet card that VMware Cloud on AWS is emulating is a 10Mb/s device. This is true even if the physical card on the server is 100Mb/s, 1Gb/s, or faster. However, VMware Cloud on AWS is not limited to 10Mb/s in this situation and transfers network packets as fast as the resources on the physical server machine allow.

For more information on virtual network adapters, see VMware KB article 1001805 and the Virtual Machine Network Configuration section of Virtual Machine Administration.