Cyclic-Reservation Multiple-Access (CRMA) is a media access protocol for high-speed LAN and MAN on slotted unidirectional bus structure. It provides both throughput efficiency and fairness in capacity allocation. In wide area networks, the Asynchronous Transfer Mode (ATM) is emerging which provides flexible transmission and switching mechanism to accommodate a large variety of services. Now the challenge is to interwork these two networks in such a way that the benefits of both are retained. In this paper we propose a new interworking protocol for CRMA/ATM networks, namely, Segregated Flow Control (SFC) protocol. The performance of the protocol is evaluated using simulation.