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 Data Center Virtual Distributed Switch (N-VDS). After migration, N-VDS handles traffic on the VLAN network.
The physical NICs and their VMkernel interfaces are initially attached to a VSS on a vSphere ESXi host. These kernel interfaces are defined on these hosts to provide connectivity to the management interface, storage, and other interfaces. After migration, the VMkernel interfaces and their associated physical NICs connect to the N-VDS and handle traffic on the VLAN and overlay transport zones.
In the following figure, if a host only has two physical NICs, you might want to assign both those NICs to the N-VDS for redundancy.
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 VMkernel interfaces: vmk0, vmk1, and vmk2.
You migrate VMkernel interfaces by using the NSX-T Data Center Manager UI or NSX-T Data Center APIs. See NSX-T Data Center API Guide.
Post migration, the vmnic0, vmnic1, and their VMkernel interfaces are migrated to the N-VDS switch. Both vmnic0 and vmnic1 are connected over VLAN and the overlay transport zones.