Efficiency of Asynchronous Transfer Mode Networks in Transporting Wide-Area Data Traffic

For performance and economic reasons, ATM networks must efficiently support the Internet family of protocols. We calculate the transmission efficiency achieved by a range of ATM-related protocols when transporting TCP and UDP wide-area traffic. We also compare the efficiency efforts of several non-standard compression techniques. To assure an accurate workload characterization, we drive these calculations with millions of wide-area packet lenghts measured on the current Internet.We find that networks using standard ATM procedures are dismally inefficient in carrying traditional data traffic -- depending on the protocols used, efficiency as seen by an application program ranges between 40 and 53 percent. Moreover, due to interaction between TCP- IP datagram lengths and ATM cell padding, efficiency responds abruptly to changes in certain protocol parameters -- for example, a 4-byte increase in ATM cell payload size can yield a 10 percent increase in efficiency. Using one compression technique in isolation can improve efficiency by 12 percent, and simultaneously using three techniques can improve it by 34 percent. These issues should be considered when designing future ATM networks.

ICSI Technical Report TR-91-043

Technical Report