Native ATM versus IP over ATM: comparative study

The main focus of this paper is native ATM versus IP over ATM solutions. We investigate the theoretical and experimental comparative performance of native ATM and CLIP. We explicitly quantify loss, throughput at the receiver (inversely proportional to delay) and CPU utilization. The key results of this work are: first, we observe a relatively important loss rate for small packet sizes which gets smaller for larger packets. UDP shows larger loss rate than native ATM. For larger packet sizes loss rate tends to zero. Second, for both UDP and native ATM, throughput at the destination is unstable for packets of small size. It reaches equilibrium for packet sizes on the order of 10k octets. Native ATM has a higher throughput owing to the smaller overhead it presents. Third, for both protocols, the CPU is used more at the receiver. At the transmitter, UDP uses more CPU than native ATM, owing to the overhead it introduces across the layers. Those results are further discussed.