When you create a transport node, it might be necessary to migrate the physical NICs and kernel interfaces from a vSphere Standard Switch (VSS) to an NSX-T Virtual Distributed Switch (N-VDS).
A vSphere ESXi host includes single or multiple physical NICs. Kernel interfaces are defined on these hosts to provide connectivity to the management interface, storage, and other interfaces.
These physical NICs and their VMkernel interfaces (vmknics) are initially attached to a VSS.
For example, if a host only has two physical NICs, you might want to assign both those NICs to the N-VDS for redundancy. Then, the vmknic of that host must be migrated to this N-VDS.
Before migration, the vSphere ESXi host has two uplinks derived from the two physical ports - vmnic0 and vmnic1. Here, vmnic0 is configured to be in an active state, attached to a VSS, whereas vmnic1 is unused. In addition, there are three vmknics: vmk0, vmk1, and vmk2.
You can use vSphere ESXi APIs to perform migration to N-VDS. See NSX-T API Guide.
Post migration, the vmnic0, vmnic1, and their vmknics are migrated to the N-VDS switch. Both vmnic0 and vmnic1 are connected over VLAN and the overlay transport zones.