A loopback interface is a logical interface that allows you to assign an IP address, which is used to identify a VMware SD-WAN Edge.
You can configure loopback interfaces only for SD-WAN Edges that are running on version 4.3 and above. The Configure Loopback Interfaces area is not available for SD-WAN Edges that are running on version 4.2 or lower. For such Edges, you must configure Management IP address. For details, refer to Configure the Management IP Address.