A VMkernel networking interface provides network connectivity for the host as well as handling VMware vMotion, IP storage, and Fault Tolerance.

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 ESXi. Because these storage types are network based, they can use the same VMkernel interface and port group.