Configuration Maximums when using virtualized networking
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Configuration Maximums when using virtualized networking


Article ID: 345242


Updated On:


VMware vSphere ESXi


This article details the relationship between physical network card limits and virtual networking technologies such as HP Virtual Connect or Cisco UCS Manager.

  • An ESXi/ESX host is presented with a number of network cards from a virtual network technology such as HP Virtual Connect or Cisco UCS Manager.
  • You want to know how the ESXi/ESX network card limits apply to an ESXi/ESX host with Virtual Connect or similar technologies from other third-party vendors.


VMware ESXi 4.1.x Embedded
VMware ESX 4.0.x
VMware vSphere ESXi 6.5
VMware ESXi 4.1.x Installable
VMware vSphere ESXi 5.5
VMware vSphere ESXi 5.0
VMware vSphere ESXi 6.0
VMware vSphere ESXi 7.0.0
VMware vSphere ESXi 6.7
VMware ESXi 4.0.x Installable
VMware vSphere ESXi 5.1
VMware ESXi 4.0.x Embedded
VMware ESX 4.1.x


ESXi/ESX have a limit on the number of network cards that can be supported in a server. For more information on these limits, see:
Note: These limits only apply to physical network cards installed on the server.

When dealing with virtualized networking technologies such as HP Virtual Connect, the number of physical network cards that are being divided up and presented to the ESXi/ESX host are relevant.

For example, with HP Virtual Connect:
  • Each 10 GB physical network card can be divided into up to 4 discrete network cards (called FlexNICs) of different speeds and presented to the ESXi/ESX host.
  • This is essentially software/firmware to make the physical NICs appear as a larger number of network cards to the host.
  • This reduces the amount of physical NICs needed for an ESXi/ESX host as the FlexNICs can be configured in the host in the same way that physical network cards can be configured. (For example, they can have different speeds and be configured on different networks/VLANs.)
For example, this configuration could be presented to a host:
  • 2 x 10 GB physical network cards divided into 8 x FlexNICs and presented to the host
  • The cards can be allocated like this:
    • 2 x 6 GB FlexNICs
    • 2 x 2 GB FlexNICs
    • 4 x 1 GB FlexNICs
  • The ESXi/ESX host detects the 8 FlexNICs as network cards with a combined bandwidth of 20 GB.
This configuration is within VMware limits and is supported because it is only using 2 x physical 10 GB network cards in HP Virtual Connect (even though the ESXi/ESX host can see 8 network cards).

Note: Configurations are supported as long as the physical network cards in the backend used to present FlexNICs do not exceed the VMware physical hardware limits.

Additional Information

Note: The links in this article were correct as of February 20th, 2013. If you find a link is broken, provide feedback and a VMware employee will update the link.

VMware ESX/ESXi 4.1 host with Broadcom bnx2x driver version 1.60.50.v41.2 experiences intermittent loss of network connectivity on HP Blades with Virtual Connect