Enabling Jumbo Frames on virtual switches

Products

• VMware vSphere ESXi
• VMware vCenter Server

Issue/Introduction

This article provides information about enabling Jumbo Frames in a virtual switch, vDS, and VMkernel adapters.

Note: If vmkernels on a virtual switch are set to 9000 MTU, the virtual switch must also be set to 9000 MTU. However, if the virtual switch is set to 9000 MTU, it is not a requirement to set all vmkernels on the virtual switch to 9000 MTU. 

 

Resolution

To enable Jumbo frames in a virtual switch, follow these steps:

1. Globally, so that all portgroups and ports in the virtual switch have Jumbo Frames enabled.
2. At the VMkernel port, so that only specific VMkernels are configured with Jumbo Frames (usually configured for storage or vMotion).

Note: Ensure that the network card, physical switches, and storage devices support Jumbo Frames before configuring.

 

Enabling Jumbo Frames for all portgroups or ports of a vDS

The MTU value of a vDS (vSphere Distributed Switch) can be configured so that all port groups and ports use Jumbo Frames.

 

To configure Jumbo Frames on a vDS in vSphere Web Client:

1. Browse to a distributed switch in the vSphere Web Client navigator.
2. Click the Actions tab, and click Settings > Edit Settings.
3. Click Advanced and set the MTU property to a value greater than 1500 bytes.
   • The MTU size cannot be set to a value greater than 9000 bytes.
   • When changing the MTU size in a vDS, the attached uplinks (physical NICs) are brought down and up again. This causes a short network outage for virtual machines and/or services that are using the uplinks.
4. Click OK.

          Note: 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.

Enabling Jumbo Frames for all portgroups or ports of a vSS

The MTU value of a vSS (vSphere Standard Switch) can be configured so that all port groups and ports use Jumbo Frames.

 

To configure Jumbo Frames on a vSS in vSphere Web Client:

1. In the vSphere Web Client, navigate to the host.
2. On the Configure tab, click Virtual Switches.
3. Navigate to the virtual switch, then click Edit.
4. Set the MTU value to 9000.
   
         

Enabling Jumbo Frames on a VMkernel port from the vCenter Server

To enable Jumbo Frames on a VMkernel port using the vSphere Web Client in vCenter Server:

1. In the vSphere Web Client, navigate to the host.
2. On the Configure tab, click VMkernel Adapters.
3. Click Edit.
4. Set the MTU value to 9000.

 

            Note: 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..

                      Changing the MTU on a virtual switch does not automatically change the MTU on VMkernel adapters.

                                                                                                                                                                       

Additional Information

For more information on configuring Jumbo frames, see iSCSI and Jumbo Frames configuration on ESX/ESXi (1007654). Jumbo frames must be configured similarly across the board on both virtual and physical infrastructure, such as vSwitch, Portgroups, VMkernel, and physical switch port.

For more information on troubleshooting host Jumbo Frame issues, as well as how to test that Jumbo Frame connectivity is working as it should be, see Troubleshooting disk latency when using Jumbo Frames with iSCSI or NFS datastores (2002197).

iSCSI and Jumbo Frames configuration on VMware ESXi/ESX (318937)
Troubleshooting disk latency when using Jumbo Frames with iSCSI or NFS datastores (2002197)



Impact/Risks:
Changing the MTU size on a vDS temporarily brings the attached physical NICs down and back up, causing a brief network outage on the vDS.