At the core of vSphere Networking are virtual switches.

vSphere supports standard switches (VSS) and distributed switches (VDS). Each virtual switch has a preset number of ports and one or more port groups.

Virtual switches allow your virtual machines to connect to each other and to connect to the outside world.

When two or more virtual machines are connected to the same virtual switch, and those virtual machines are also on the same port group or VLAN, network traffic between them is routed locally.

When virtual machines are connected to a virtual switch that is connected to an uplink adapter, each virtual machine can access the external network through that uplink. The adapter can be an uplink connected to a standard switch or a distributed uplink port connected to a distributed switch.

Virtual switches allow your ESXi host to migrate virtual machines with VMware vMotion and to use IP storage through VMkernel network interfaces.

Using vMotion, you can migrate running virtual machines with no downtime. You can enable vMotion with vicfg-vmknic --enable-vmotion. You cannot enable vMotion with ESXCLI.

IP storage refers to any form of storage that uses TCP/IP network communication as its foundation and includes iSCSI and NFS for ESXi. 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. The VMkernel TCP/IP stack is also separate from the guest operating system's network stack. Each of these stacks accesses various networks by attaching to one or more port groups on one or more virtual switches.