Today I would like to talk about difference in various types of vNIC in ESX 4. Need to note that this device have no physical analogues, and can be used only if VmWare Tools are installed. VMXNET - first generation, optimized for network performance between VMs.
VMXNET2 or Enhanced - simple VMXNET, but with few additional features – Jumbo Frames (only in 10Gb networks) and TCP Segmentation Offloading (TSO). This vNIC is available beginning from ESX 3. It is also worth mentioning that you need to read this article in VmWare`s Knowledge Base for using this adapter in Windows 2003 (not Enterpise and datacenter editions).
VMXNET3 - next generation of vNIC, now it uses paravirtualization (in a nutshell – earlier everything was virtualized, now parts of commands are sent directly to pNIC). VMXNET3 is not a subset of vNICs of previous generations, but supports all of their functions. It is available only in VMs with virtual hardware v7 and higher.
Now, when we`ve classified types of vNICs, let`s see what kinds of adapters are used in VMs:
Vlance - virtual analog of AMD 79C970 PCnet32 LANCE NIC. Drivers are available in all OSes till Vista. Used in VMs without VmTools.
Flexible - while OS is booting, it operates as Vlance. If VmTools are installed on VM, it will operate as VMXNET, if not – as Vlance.
E1000 – is an emulated analog of Intel 82545EM Gigabit Ethernet NIC.
In addition, I would like to list all functions available in all vNICs in the table below:
|
Flexible |
Enchanced vmxnet |
E1000 |
vmxnet3 |
|
| IPv4 TSO |
- |
+ |
+ |
+ |
| IPv6 TSO |
- |
- |
- |
+ |
| Jumbo Frames |
- |
+ |
- |
+ |
| Large Ring Sizes |
- |
- |
+ |
+ |
| RSS |
- |
- |
- |
+ |
| MSI-X |
- |
- |
- |
+ |
| Virtual hardware version |
4 or 7 |
4 or 7 |
4 or 7 |
Only7 |