VMware ESXi and vSphere Cluster Management
VMware ESXi Virtual Network Adapter Types
Compare Flexible, E1000, E1000E, VMXNET2, and VMXNET3 virtual NICs in VMware vSphere, and learn how to choose and change the right adapter.
A virtual network interface card (vNIC) is a software-defined network adapter assigned to a virtual machine. It connects the guest operating system to a VMware virtual switch, port group, and—when configured— the wider physical network.
VMware vSphere offers both emulated adapters and paravirtualized adapters. An emulated adapter behaves like a named physical Ethernet controller, allowing the guest to use a standard hardware driver. A paravirtualized adapter is virtualization-aware and uses a specialized guest driver to communicate more efficiently with the hypervisor.
The adapter model affects guest-driver availability, compatibility, throughput, CPU consumption, boot-time network access, and advanced capabilities such as jumbo frames, offloads, multiqueue processing, and IPv6 offloads.
VMware Virtual Network Adapter Types at a Glance
| Adapter type | Adapter category | Emulated or paravirtualized model | Guest driver source | Notable capabilities | Compatibility considerations | Recommended use |
|---|---|---|---|---|---|---|
| Flexible | Legacy compatibility | Vlance initially; VMXNET behavior with VMware Tools | Guest Vlance driver or VMware Tools | Basic 10 Mbps emulation without Tools; higher-performance operation with Tools | Mainly older 32-bit guests with limited driver support | Exceptional legacy compatibility cases |
| E1000 | Emulated | Intel 82545EM Gigabit Ethernet | Usually an operating-system inbox Intel driver | Broad operating-system compatibility | More CPU and emulation overhead than VMXNET3 | Legacy Windows or Linux guests and installation-stage connectivity |
| E1000E | Emulated | Intel 82574L Gigabit Ethernet | Operating-system driver for the newer emulated Intel model | Compatibility with supported newer Windows guests | Only use where the guest supports this model | Compatibility choice for Windows 8-era and newer guests |
| VMXNET2 | Paravirtualized | Enhanced VMXNET | VMware Tools | Jumbo frames and hardware offload support | Legacy option; generally superseded by VMXNET3 | Existing older VMs that specifically require it |
| VMXNET3 | Paravirtualized | Modern VMware virtual NIC | VMware Tools-provided driver | Jumbo frames, offloads, multiqueue, IPv6 offloads, and other performance features | Requires virtual hardware version 7 or later and guest-driver support | Preferred choice for supported new and production VMs |
Flexible Adapter
Flexible is a legacy compatibility-oriented virtual adapter. It initially presents a Vlance device, which is based on AMD PCnet32/LANCE emulation. Without VMware Tools, the guest sees basic emulated behavior equivalent to a 10 Mbps adapter.
When VMware Tools is installed, Flexible can use VMware's higher-performance VMXNET operation instead of remaining limited to the basic Vlance behavior. This makes it more adaptable than a fixed legacy emulated device, but it does not make Flexible the preferred choice for modern deployments.
Flexible is mainly relevant to older 32-bit operating systems that lack drivers for newer virtual NIC models. For a new supported guest, use VMXNET3 instead.
E1000 Adapter
E1000 emulates the Intel 82545EM Gigabit Ethernet controller. Many operating systems include a compatible Intel driver, so an E1000 adapter can provide network access during operating-system installation or before VMware Tools is available.
E1000 has been particularly useful with legacy Windows and Linux guests. It was also historically used as a default or compatibility option for some 64-bit guest operating systems. Its main advantage is driver availability, not maximum virtual-network efficiency.
Because E1000 is hardware emulation, the hypervisor must reproduce the behavior of a physical controller. That generally creates more processing overhead and can reduce scalability compared with a paravirtualized adapter such as VMXNET3.
E1000E Adapter
E1000E emulates the Intel 82574L Gigabit Ethernet controller. It is intended for guest operating systems that support this newer emulated Intel adapter model.
E1000E is available for Windows 8-era and newer Windows guest operating systems when the relevant driver is present. Select it when compatibility with a particular guest or installation process is more important than the lower overhead and broader performance features of VMXNET3.
E1000E remains an emulated device. VMware Tools is not required for its basic operation if the guest already contains a suitable driver, although VMware Tools is still useful for other guest integration functions.
VMXNET2 / Enhanced VMXNET
VMXNET2, also called Enhanced VMXNET, is an improved version of the earlier VMXNET paravirtualized adapter. A paravirtualized device relies on a virtualization-aware guest driver rather than imitating every detail of physical Ethernet hardware.
VMXNET2 provides performance-oriented capabilities beyond basic emulated adapters, including jumbo frames and hardware offload support. Jumbo frames are Ethernet frames larger than the normal 1500-byte MTU. Hardware offload means that selected network-processing tasks are delegated from the guest networking stack to the virtual adapter or virtualization layer.
VMXNET2 is now a legacy high-performance option. In most new deployments, VMXNET3 provides a better feature set and should be selected instead. Keep VMXNET2 when an existing workload or platform compatibility requirement specifically depends on it.
VMXNET3
VMXNET3 is the preferred high-performance paravirtualized virtual NIC when the guest operating system supports it. The guest requires the VMware Tools-provided VMXNET3 driver; an operating-system inbox driver is not assumed.
VMXNET3 supports performance-oriented features such as:
- Jumbo frames, when the entire network path supports a consistent MTU.
- Network hardware offloads that reduce guest CPU processing.
- Multiqueue processing, which uses multiple transmit and receive queues to spread network work across CPUs.
- IPv6 offloads and other platform-dependent networking enhancements.
- Additional capabilities that improve throughput and scalability for multi-vCPU workloads.
VMXNET3 requires virtual hardware version 7 or later. A virtual hardware version is the compatibility level of a VM; it controls which virtual devices and capabilities can be presented.
VMXNET3 also supports VMware Fault Tolerance and record/replay features where those capabilities are supported by the relevant vSphere platform generation, VM compatibility level, and workload configuration. Always verify the requirements for the specific vSphere release.
Compared with E1000-family adapters, VMXNET3 usually reduces emulation overhead. The specialized driver allows more direct coordination between the guest and virtualization layer, which commonly improves CPU efficiency, throughput, and scalability.
Choosing an Adapter Type
| Guest condition | Preferred adapter | Why | Important prerequisite or caution |
|---|---|---|---|
| Modern supported guest with VMware Tools | VMXNET3 | Provides high performance with lower emulation overhead | Install or update VMware Tools and verify virtual hardware version 7 or later |
| Guest installation before VMware Tools | E1000 or E1000E | Often uses an operating-system inbox Intel driver | Select the model supported by the guest operating system |
| Legacy guest with limited drivers | Flexible | Vlance compatibility may work where modern drivers do not | Use only as a legacy exception, especially for older 32-bit systems |
| Workload requiring high throughput or multiqueue processing | VMXNET3 | Supports multiqueue, offloads, jumbo frames, and related features | Configure and validate MTU consistently across the complete network path |
| VM requiring a virtual NIC model change | VMXNET3 after preparation | Can improve efficiency after driver readiness is confirmed | Plan downtime, record IP settings, and check for new-interface and MAC-address effects |
Use VMXNET3 whenever guest support, VMware Tools installation, and virtual hardware compatibility allow it. Choose E1000 or E1000E when the guest needs a standard emulated driver before Tools can be installed. Use Flexible only for exceptional legacy compatibility requirements.
Before changing an adapter, consider migration and cloning behavior, boot-time network availability, guest driver support, application licensing, and any configuration that depends on the adapter's MAC address. A replacement adapter may be detected as new hardware, causing the guest to retain settings on the old interface.
Selecting the Adapter During VM Provisioning
- Create a virtual machine or open the settings of an existing VM.
- Add or edit the Network Adapter virtual hardware item.
- Select the required adapter model in the adapter-type setting.
- Connect the vNIC to the intended standard-switch port group or distributed port group.
- For VMXNET3, install or update VMware Tools in the guest.
- Confirm that the VM's virtual hardware compatibility level supports the selected device.
- Start the VM and verify driver recognition, IP configuration, link status, and network reachability.
Review or change the adapter model from the VM's virtual hardware configuration. Depending on the vSphere version and operation, changing the model may require the VM to be powered off. Plan an outage when necessary.
After the change, verify the model in vSphere and then verify the detected adapter and driver inside the guest. Recheck IP address, VLAN-related connectivity, routes, DNS, firewall rules, and application bindings.
Practical Selection Examples
New supported Windows or Linux server
Choose VMXNET3, install VMware Tools, and confirm that the VM's hardware compatibility level is sufficient. This provides the best available combination of performance features and lower emulation overhead.
Legacy guest without a VMXNET driver
Choose E1000 or E1000E according to the guest's supported Intel driver. This can provide network connectivity during installation and allow VMware Tools to be installed later.
Older 32-bit operating system
Choose Flexible when the guest cannot use a modern virtual NIC driver and requires broad Vlance compatibility. Treat this as a compatibility exception rather than a performance recommendation.
Moving an existing VM from E1000 to VMXNET3
Install or update VMware Tools first, record the current IP configuration, schedule a maintenance window, change the adapter, and boot the guest. Confirm that the new interface has the expected settings and that connectivity returns. Remove or disable stale interface configuration only after confirming that it is no longer needed.
High-throughput multi-vCPU VM using jumbo frames
Choose VMXNET3 and configure jumbo frames only when the guest, virtual switch or distributed switch, physical uplinks, physical switches, destination network, and complete traffic path support the same MTU. A large MTU configured in only one location will not provide reliable jumbo-frame traffic.
Troubleshooting Virtual NIC Selection
No network connection after changing to VMXNET3
- Confirm the selected adapter type and connected state in VM settings.
- Install, repair, or update VMware Tools so the VMXNET3 driver is available.
- Check Device Manager or the guest's network-interface list for the newly detected adapter.
- Reapply IP, VLAN-related, routing, DNS, and firewall settings as required.
- Check that the vNIC is attached to the correct port group.
VMXNET3 is unavailable
The VM may have a virtual hardware compatibility level below version 7, or platform, guest operating system, or management-tool constraints may prevent selection. Review the compatibility level and upgrade virtual hardware only after checking operational impact, backups, and rollback plans. If an upgrade is not appropriate, use a compatible emulated adapter.
Jumbo-frame traffic fails
Validate the MTU end to end across the guest, virtual switch or distributed switch, relevant VMkernel paths, physical switches, destination network, and intermediate routing path. Test with appropriately sized probes where supported. If end-to-end jumbo-frame support cannot be guaranteed, return to a standard MTU.
The guest cannot find an emulated-adapter driver
The selected E1000 or E1000E model may not be supported by that guest release, or the installation media may lack the required driver. Choose a model with a supported inbox driver or supply a vendor-supported driver during installation. After initial connectivity is available, install VMware Tools and consider VMXNET3 if supported.
Key Takeaways
- Flexible is a legacy Vlance-compatible adapter for exceptional older-guest requirements.
- E1000 emulates Intel 82545EM; E1000E emulates Intel 82574L.
- E1000-family adapters are useful for broad driver compatibility but generally have more emulation overhead.
- VMXNET2 is an older enhanced paravirtualized option with jumbo-frame and offload support.
- VMXNET3 is the usual choice for supported modern guests and requires the VMware Tools driver.
- Changing a vNIC can create a new guest interface, so preserve and verify network configuration before making the change.
For related administration tasks, see Create Virtual Machines, Add Virtual Hardware to a VM, Edit Virtual Machine Settings, and Install a Guest Operating System.