Implementing traffic shaping

Abstract

Traffic shaping is important in ATM networks, especially those that are interconnected or provide service guarantees. We examine what shaping may be considered ideal, and what is attainable under the constraints of transmission systems and cost. We justify the use of FCFS multiplexing of multiple single-stream shaper outputs as a performance reference for multi-stream shapers, but also point out some of its deficiencies. Shaper implementations in which transmissions are scheduled on cell arrivals, emissions, and transmissions are examined and compared both qualitatively and through simulation. We identify the problem of shaping cells that must conform to multiple traffic constraints (e.g. when the rate of a multicast connection must be adapted to suit multiple links) and examine implementations to achieve this. Shaping in which inevitable cell delay variation is intentionally distributed inequitably amongst connections (to assist CDV-intolerant connections) is also examined.<>