Emerging real-time and multimedia applications in IP over ATM networks are becoming an indispensable part of the networking world. Considering the different and essential natures of IP and ATM, it seems that they complement each other. Although several approaches have been proposed for IP and ATM integration, so far a key problem (i.e., Quality of Service support) in foreseeable future networking applications remains unsolved. This paper describes a new extension to Classical IP and ARP over ATM (CLIP) protocol, Real-time and Multimedia services using CLIP (RMCLIP), providing ATM service classes to the IP end users. It defines that different service classes are mapped to the associated IP addresses. It enables different IP end user applications (e.g., real-time video, voice and data) to obtain their own dedicated VCs.