Improved Analysis of Early Packet Discard

In a previous paper, one of the authors, gave a worst-case analysisfor the Early Packet Discard technique for maintaining packet integrityduring overload in ATM switches. This analysis showed that to ensure100% goodput during overload under worst-case conditions, requires a bufferwith enough storage for one maximum length packet from every active virtualcircuit. This paper refines that analysis, using assumptions that arecloser to what we expect to see in practice. Our principal result is that100% goodput can be achieved with substantially smaller buffers,although the required buffer space can be significant when the link speed issubstantially higher than the rate of the individual virtual circuits.These results are validated by comparison with simulation. We also givea simple analysis to determine the amount of buffering needed to boundthe probability of buffer overflow and underflow.