A VMkernel networking interface is used for VMware VMotion and IP storage.

Moving a virtual machine from one host to another is called migration. Using VMotion, you can migrate powered on virtual machines with no downtime. Your VMkernel networking stack must be set up properly to accommodate VMotion.

IP storage refers to any form of storage that uses TCP/IP network communication as its foundation, which includes iSCSI and NFS for ESX. Because these storage types are network based, they can use the same VMkernel interface and port group.

The network services that the VMkernel provides (iSCSI, NFS, and VMotion) use a TCP/IP stack in the VMkernel. This TCP/IP stack is completely separate from the TCP/IP stack used in the service console. Each of these TCP/IP stacks accesses various networks by attaching to one or more port groups on one or more vSwitches.