The VMkernel port (or the VMkernel adapter or interface) is used for VMkernel services when we need to connect to the physical network. VMkernel adapters are used (and needed) for IP-based storage (such as NFS or iSCSI), for vSAN, for vMotion traffic, for vSphere FT logs, for management interfaces, for vSphere Replication, and for NSX-VTEP or VSAN.
The following services are supported on VMkernel NICs:
- Management traffic
- vMotion traffic
- Provisioning traffic
- IP storage traffic and discovery
- Fault tolerance traffic
- vSphere Replication traffic
- vSphere Replication NFC traffic
- vSAN traffic
Again, VMkernel adapters can be configured from ESXi host client, vCenter Server, or the CLI.
Please note that a port group can either be used for VMs or VMkernel ports, not both simultaneously. You can, of course, create two port groups with the same VLAN ID for this reason.