Analysis of Internet services in IP over ATM networks

This article presents a trace-driven analysis of IP over ATM services from an ATM-centric standpoint. We provide a characterization of TCP flows as VBR streams with burstiness (MBS) and throughput (SCR). On the other hand, a macroscopic analysis comprising percentage of flows and bytes per service, TCP average transaction duration, and bytes transferred both ways is also presented. The ATM link under analysis concentrates traffic from a large population of 1500 hosts from the Public University of Navarra campus network, that produce 1,700,000 TCP connections approximately in the measurement period of one week. The results obtained from such a wealth of data indicate that the sustained throughput of Web connections does not grow beyond 80 kb/s with 70 percent probability in the data transfer phase (i.e., in the established state), and we observe a strong influence of the connection establishment phase on the user-perceived throughput. On the other hand, the burstiness of individual TCP connections is rather small; namely, TCP connections do not produce bursts according to the geometric law given by slow start and commonly assumed in previously published studies.