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