A scheme for implementing GFR service in an ATM environment, e.g., an access node's ATM switch fabric. Regulation of a GFR flow is throttled between two modes, a guaranteed rate mode and a non-guaranteed rate mode, depending upon timestamps computed by applicable traffic policer/shaper algorithms. A scheduler is operably coupled to a policing block for scheduling cells from a guaranteed flow queue for transport via the ATM fabric at a guaranteed rate upon determining the onset of a guaranteed service frame. The scheduler switches to non-guaranteed rate mode for scheduling cells from the flow queue at a non-guaranteed rate when a timestamp (TS.sub.NGF) for transmission at the non-guaranteed rate is earlier than a timestamp (TS.sub.GF) for transmission of a next guaranteed service frame at the guaranteed rate.