Network arrivals are often modeled as Poisson processes for analytic simplicity, even though a number of traffic studies have shown that packet interarrivals are not exponentially distributed. We evaluate 24 wide-area traces, investigating a number of wide-area TCP arrival processes (session and connection arrivals, FTP data connection arrivals within FTP sessions, and TELNET packet arrivals) to determine the error introduced by modeling them using Poisson processes. We find that user-initiated TCP session arrivals, such as remotelogin and file-transfer, are well-modeled as Poisson processes with fixed hourly rates, but that other connection arrivals deviate considerably from Poisson; that modeling TELNET packet interarrivals as exponential grievously underestimates the burstiness of TELNET traffic, but using the empirical Tcplib [Danzig et al, 1992] interarrivals preserves burstiness over many time scales; and that FTP data connection arrivals within FTP sessions come bunched into “connection bursts,” the largest of which are so large that they completely dominate FTP data traffic. Finally, we offer some results regarding how our findings relate to the possible self-similarity of widearea traffic.

We report results from a longitudinal analysis of the IP traffic workload seen at a single measurement site inside a major Internet traffic exchange point. Using data collected by the NLANR/MOAT Network Analysis Infrastructure (NAI) project [NAI] and analysis software from CAIDA's CoralReef project [CoralReef], we present trends in application usage seen at the NASA Ames Internet Exchange over 10 months, from May 1999 through March 2000. We show changes in the fraction of traffic from streaming media and online gaming, as well as an increase in traffic from new applications such as Napster and IPSEC tunneling. We also show that our data does not indicate any overall change in the TCP/UDP traffic ratio at the Ames Internet Exchange during this period, or significant differences from the analyses by MCI Worldcom and CAIDA in 1998.

We present the results of a study of Internet round-trip delay. The links chosen include links to frequently accessed commercial hosts as well as well-known academic and foreign hosts. Each link was studied for a 48-hour period. We attempt to answer the following questions: (1) how rapidly and in what manner does the delay change -- in this study, we focus on medium-grain (seconds/minutes) and coarse-grain time-scales (tens of minutes/hours); (2) what does the frequency distribution of delay look like and how rapidly does it change; (3) what is a good metric to characterize the delay for the purpose of adaptation. Our conclusions are: (a) there is large temporal and spatial variation in round-trip time (RTT); (b) RTT distribution is usually unimodal and asymmetric and has a long tail on the right hand side; (c) RTT observations in most time periods are tightly clustered around the mode; (d) the mode is a good characteristic value for RTT distributions; (e) RTT distributions change slow...

As the NSFNET backbone service migrates into a commercial environment, so will access to the only set of publicly available statistics for a large national U.S. backbone. The transition to the new NSFNET program, with commercially operated services providing both regional service as well as cross-service provider switching points, or Network Access Points (NAPs), will render statistics collection a much more difficult endeavor. In this paper we discuss issues and complexities of statistics collection at recently deployed global network access points such as the U.S. federal NAPs. 1 background The United States National Science Foundation (NSF) is making a transition away from supporting Internet backbone services for the general research and education community. One component of these services, the NSFNET backbone, was dismantled as of the end of April 1995. To facilitate a smooth transition to a multi-provider environment, and hopefully forestall the potential for network partitioni...

Packet based, e.g., Internet, traffic will soon surpass conventional forms of wired communication, e.g., circuit-switched voice traffic. Moreover, the growth in packet traffic is so pronounced that by 2007, telephony may constitute only 10% of overall backbone traffic. In this paper, we investigate this transition of the communication network from a "voice-centric" to a "data-centric" model. In particular, we examine the speed with which data traffic will eclipse voice traffic, and the significance of the shift's suddenness to the final outcome. While a prediction concerning the precise timing of the circuit-to-packet crossover is of some interest, this paper's focus is on addressing the fundamental issues relevant to the rapid evolution of a data dominated communication network. To aid in understanding the shift, we present and characterize a traffic transition model. Based on this model, we determine that the window in which data traffic increases to contribute 90% of overall backb...

At the Computer Systems Laboratory at UCSD, we conduct research in operating systems, communication networks, and performance evaluation. This document reviews the current research within the Computer Systems Laboratory. The final section contains descriptions of research projects undertaken by our students. For more information, contact the authors at the above address, or by FAX at (619) 534-7029. Joseph Pasquale may be contacted by e-mail at pasquale@ucsd.edu or by telephone at (619) 534-2673. George Polyzos may be contacted by e-mail at polyzos@ucsd.eduor by telephone at (619) 534-3508. 1 1 Introduction At the UCSD Computer Systems Laboratory (CSL), we conduct research in operating systems, communication networks, and performance evaluation. In operating systems, we are focusing on high performance I/O software support for a variety of I/O intensive applications, such as multimedia applications and scientific applications. In communication networks, we concentrate on problems a...

We present the 1993 annual report on research efforts of the San Diego Supercomputer Center's Applied Network Research group (ANR). Our projects were undertaken in collaboration with the Computer Systems Laboratory of the University of California in San Diego (CSL), as well as a number of other researchers across the country. This year, we continued our research on network analysis and modeling, as well as advanced network technologies including the CASA gigabit testbed. Our research topics include issues of network access, instrumentation for the accurate gathering of performance statistics, accounting, and quality of service in the Internet. We hope interested parties within the Internet research community will find this report helpful in understanding our research agenda. We also wish to use this report to stimulate further discussion and interaction among researchers pursuing similar projects and goals. Any opinions, conclusions, or recommendations in this report are thos...