Jumbo frames let ESXi hosts send larger frames out onto the physical network. The network must support jumbo frames end-to-end that includes physical network adapters, physical switches, and storage devices.

Before enabling jumbo frames, check with your hardware vendor to ensure that your physical network adapter supports jumbo frames.

You can enable jumbo frames on a vSphere distributed switch or vSphere standard switch by changing the maximum transmission unit (MTU) to a value greater than 1280 bytes. With vCenter Server 7.0 Update 3, you can set the size of the maximum transmission unit (MTU) on a vSphere Distributed Switch to up to 9190 bytes to support switches with larger packet sizes.

Enable Jumbo Frames on a vSphere Distributed Switch

Enable jumbo frames for the entire traffic that passes through a vSphere Distributed Switch.

Important: When you change the MTU size of a vSphere Distributed Switch, the physical NICs that are assigned as uplinks are brought down and up again. This causes a short network outage of between 5 to 10 milliseconds for virtual machines or services that are using the uplinks.

Procedure

  1. On the vSphere Client Home page, click Networking and navigate to the distributed switch.
  2. On the Configure tab, expand Settings and select Properties.
  3. Click Edit.
  4. Click Advanced and set the MTU property to a value greater than 1500 bytes.
    You cannot set the MTU size to a value greater than 9190 bytes.
  5. Click OK.

Enable Jumbo Frames on a vSphere Standard Switch

Enable jumbo frames for all traffic through a vSphere Standard Switch on a host.

Procedure

  1. In the vSphere Client, navigate to the host.
  2. On the Configure tab, expand Networking and select Virtual Switches.
  3. Select a standard switch from the virtual switch table and click Edit settings.
  4. In the Properties section, set the MTU property to a value greater than 1500 bytes.
    You can increase the MTU size up to 9000 bytes.
  5. Click OK.

Enable Jumbo Frames for a VMkernel Adapter

Jumbo frames reduce the CPU load caused by transferring data. Enable jumbo frames on a VMkernel adapter by changing the maximum transmission units (MTU) of the adapter.

Procedure

  1. In the vSphere Client, navigate to the host.
  2. On the Configure tab, expand Networking and select VMkernel adapters.
  3. Select a VMkernel adapter from the adapter table.
    The properties of the adapter appear.
  4. Click Edit.
  5. On the Port properties page, set the MTU property to a value greater than 1500.
    You can increase the MTU size up to 9000 bytes.
  6. Click OK.

Enable Jumbo Frame Support on a Virtual Machine

Enabling jumbo frame support on a virtual machine requires an enhanced VMXNET adapter for that virtual machine.

Procedure

  1. Locate the virtual machine in the vSphere Client.
    1. Select a data center, folder, cluster, resource pool, or host and click the VMs tab.
    2. Click Virtual Machines and click the virtual machine from the list.
  2. From the Actions menu, select Edit Settings.
  3. Select the Virtual Hardware tab in the dialog box displaying the settings.
  4. Expand the Network adapter section. Record the network settings and MAC address that the network adapter is using.
  5. Click the times-circle button to remove the network adapter from the virtual machine.
  6. From the Add new device drop-down menu, select Network Adapter.
    The New Network section is added to the list in the Virtual Hardware tab.
  7. Expand the New Network section.
  8. From the Adapter Type drop-down menu, select VMXNET 2 (Enhanced) or VMXNET 3.
  9. Set the network settings to the ones recorded for the old network adapter.
  10. Set the MAC Address to Manual, and type the MAC address that the old network adapter was using.
  11. Click OK.

What to do next

  • Check that the enhanced VMXNET adapter is connected to a standard switch or to a distributed switch with jumbo frames enabled.
  • Inside the guest operating system, configure the network adapter to allow jumbo frames. See the documentation of your guest operating system.
  • Configure all physical switches and any physical or virtual machines to which this virtual machine connects to support jumbo frames.