FPGA based ATM traffic shaper for event-building networks

It has been proposed to use ATM multistage switching fabrics in high energy physics experiments to assemble the data associated with a collision, that are spread amongst many sources, and transmit it to one of many destinations where it will be analysed. This concentration of data, together with the burstiness caused by the simultaneous trigger of data sources for every event would inevitably produce congestion in the switching fabrics unless traffic shaping is applied at the input. We have studied several traffic shaping schemes. These include three types of barrel shifters and a traffic randomization method. For the latter case we have designed and implemented hardware components, based on ASICs and FPGAs, that will be integrated in a VME based ATM data source module