Time-based scheduler architecture and method for ATM networks

摘要

A flexible and scalable architecture and method that implements dynamic rate control scheduling in an ATM switch. The scheduler shapes a large number of streams according to rate values computed dynamically based on switch congestion information. To handle a large range of bit rates, a plurality of timewheels are employed with different time granularities. The streams are assigned dynamically to the timewheels based on computed rate values. The shaper architecture and method supports priority levels for arbitrating among streams which are simultaneously eligible to transmit. Specifically, a scheduling timestamp is determined by the scheduler in consideration of a dynamic rate varied in dependency upon congestion information, a peak cell rate, and/or a sustainable cell rate, and a burst threshold while a shaping timestamp is also determined with reference to the scheduling timestamp determined by the above-mentioned manner. The scheduler may shape a stream in accordance with a rate determined by an ABR mechanism along with the dynamic rate.