VMkernel Networking

VMkernel networking carries management traffic but it also carries all other forms of traffic that originate with the ESXi host itself, except the traffic that is generated by the VMs running on that ESXi host.  VMkernel ports are used for:

• Management
• vMotion
• iSCSI
• NAS access
• NFS access
• Virtual SAN
• vSphere Replication
• vSphere Fault Tolerance (FT)

That's essentially all types of traffic that is generated by the hypervisor itself.

Provisioning Traffic handles the data transfer for virtual machine cloning, cold migration, and snapshot creation.  This can be a traffic-intensive process, especially so if VAAI is not leveraged.  vSphere Replication Traffic transmits replicated blocks from an ESXi host to a vSphere Replication Appliance whereas vSphere Replication NFC Traffic handles the Network File Copy from the vSphere Replication Appliance to the destination datastore through an ESXi host.

A VMkernel port consists of two components: a port group on a virtual switch and a VMkernel interface, also known as vmknic.

Important to note
There exists a one-to-one relationship with an interface: each VMkernel NIC, or vmknic requires a matching VMkernel port group on a virtual switch.  In addition, these interfaces require IP addresses for management or VMkernel network access.