What is a requirement for configuring a PPPoE client?

To configure a PPPoE (Point-to-Point Protocol over Ethernet) client, it is essential to have an interface that will be used for the PPPoE connection. This interface acts as the point of entry for the PPPoE client to communicate with the PPPoE server. The PPPoE client needs to know which physical or virtual interface to bind to in order to send and receive PPPoE discovery and session packets. Without this interface, the PPPoE client would not be able to establish a connection to the remote network, as there would be no pathway for the data to travel through.

While other options may seem relevant in different networking contexts, the primary requirement for setting up a PPPoE client focuses on the necessity of a designated interface for operational capabilities.