When using TSO on a VMkernel network adapter, the physical NIC splits large data chunks into TCP segments instead of the CPU. As a result, the CPU has more cycles for applications. By default, a host is configured to use hardware TSO if its NICs support it.

If TSO becomes disabled for a particular VMkernel adapter, the only way you can re-enable TSO is by deleting the adapter and recreating it with TSO enabled.


Verify that one of the following requirements are satisfied:

  • The VMkernel adapter does not handle traffic related to host networking services, such as iSCSI, vSphere vMotion, and so on.
  • The networking services can send traffic by using an alternative VMkernel adapter.


  1. In the vSphere Web Client, navigate to the host.
  2. Under Manage, select Networking and then select VMkernel adapters.
  3. Select a VMkernel adapter from the list, and note its settings.
    Later you should set the same settings to the newly added VMkernel adapter.
  4. Click Remove.
  5. In the confirmation dialog, click Analyze impact, verify that no networking services are impacted, and click OK.
  6. In the VMkernel adapters list, click Add host networking.
  7. On the Add connection type page, select VMkernel Network Adapter and click Next.
  8. On the Select target device page, assign the VMkernel adapter to a standard switch or distributed port group.
  9. On the Port properties page, configure the IP version and networking services related to the old adapter, and click Next.
  10. On the IPv4 Settings and IPv6 Settings pages, configure the IP settings used by the old adapter.
  11. Review your settings and click Finish.