This document describes how application clients can request IP-based Bidirectional Forwarding Detection (BFD) sessions while either being IP agnostic themselves or while dealing with IP unnumbered interfaces. A dedicated well-known multicast IP address 224.XXX.XXX.XXX is used as the destination IP address of the BFD packets when running BFD for interface. It allows for BFD sessions on interfaces that may have no IP addresses, either because the interface is unnumbered or because the layer 3 protocol status of the interfaces is not up yet. One application of BFD for interface is to run BFD over LAG/Bundle component links. An example will be given in this document.