The authors address the role of marketing in hypermedia computer-mediated environments (CMEs). Their approach considers hypermedia CMEs to be large-scale (i.e., national or global) networked enviro...

/pdf/marketing-in-hypermedia-computer-mediated-environments-2ffhdnb9gv.pdf

Marketing in Hypermedia Computer-Mediated Environments: Conceptual Foundations

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 remote-login 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 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 wide area traffic. >

/pdf/wide-area-traffic-the-failure-of-poisson-modeling-3ve28sph9q.pdf

Wide area traffic: the failure of Poisson modeling

We discuss gateway queueing algorithms and their role in controlling congestion in datagram networks. A fair queueing algorithm, based on an earlier suggestion by Nagle, is proposed. Analysis and s...

Analysis and simulation of a fair queueing algorithm

We discuss gateway queueing algorithms and their role in controlling congestion in datagram networks. A fair queueing algorithm, based on an earlier suggestion by Nagle, is proposed. Analysis and simulations are used to compare this algorithm to other congestion control schemes. We find that fair queueing provides several important advantages over the usual first-come-first-serve queueing algorithm: fair allocation of bandwidth, lower delay for sources using less than their full share of bandwidth, and protection from ill-behaved sources.

/pdf/analysis-and-simulation-of-a-fair-queueing-algorithm-2fo075ttlu.pdf

We present a computational technique for combatting junk mail in particular and controlling access to a shared resource in general. The main idea is to require a user to compute a moderately hard, but not intractable, function in order to gain access to the resource, thus preventing frivolous use. To this end we suggest several pricing Junctions, based on, respectively, extracting square roots modulo a prime, the Fiat-Shamir signature scheme, and the Ong-Schnorr-Shamir (cracked) signature scheme.

https://web.cs.dal.ca/~abrodsky/7301/readings/DwNa93.pdf

Pricing via Processing or Combatting Junk Mail

The relative performance of different data collection methods in the assessment of various traffic parameters is significant when the amount of data generated by a complete trace of a traffic interval is computationally overwhelming, and even capturing summary statistics for all traffic is impractical. This paper presents a study of the performance of various methods of sampling in answering questions related to wide area network traffic characterization. Using a packet trace from a network environment that aggregates traffic from a large number of sources, we simulate various sampling approaches, including time-driven and event-driven methods, with both random and deterministic selection patterns, at a variety of granularities. Using several metrics which indicate the similarity between two distributions, we then compare the sampled traces to the parent population. Our results revealed that the time-triggered techniques did not perform as well as the packet-triggered ones. Furthermore, the performance differences within each class (packet-based or time-based techniques) are small.

Application of sampling methodologies to network traffic characterization

Field biologists and ecologists are starting to open new avenues of inquiry at greater spatial and temporal resolution, allowing them to “observe the unobservable” through the use of wireless sensor networks. Sensor networks facilitate the collection of diverse types of data (from temperature to imagery and sound) at frequent intervals—even multiple times per second—over large areas, allowing ecologists and field biologists to engage in intensive and expansive sampling and to unobtrusively collect new types of data. Moreover, real-time data flows allow researchers to react rapidly to events, thus extending the laboratory to the field. We review some existing uses of wireless sensor networks, identify possible areas of application, and review the underlying technologies in the hope of stimulating additional use of this promising technology to address the grand challenges of environmental science.

https://bioone.org/journals/BioScience/volume-55/issue-7/0006-3568(2005)055[0561:WSNFE]2.0.CO;2/Wireless-Sensor-Networks-for-Ecology/10.1641/0006-3568(2005)055[0561:WSNFE]2.0.CO;2.pdf

Wireless Sensor Networks for Ecology

The National Laboratory for Applied Network Research is creating a network analysis infrastructure (NAI) to support network research and engineering of high performance research networks. The NAI includes a passive monitoring project, an active monitoring project, and the collection of network management and control data. Together these projects have deployed more than 120 monitors around the high-performance research networks in the United States. This article describes NAI and the projects using it. The article concludes with a discussion of the future plans for the infrastructure.

The NLANR Network Analysis Infrastructure

The results of a measurement study of the T1 NSFNET backbone are presented. The measurement environment and the approach to data collection are discussed. Measurements results are then presented for: long-term growth in traffic volume, including attribution to domains and protocols; trends in average packet size on the network, over both long- and medium-term intervals; most popular sources, destinations, and site pairs; traffic locality; international distribution of traffic; mean utilization statistics of the overall backbone as well as of specific links of interest: and delay statistics. >

Traffic characteristics of the T1 NSFNET backbone

We analyze two days of queries to the popular NCSA Mosaic server to assess the geographic distribution of transaction requests. The wide geographic diversity of query sources and popularity of a relatively small portion of the web server file set present a strong case for deployment of geographically distributed caching mechanisms to improve server and network efficiency. The NCSA web server consists of four servers in a cluster. We show time series of bandwidth and transaction demands for the server cluster and break these demands down into components according to geographical source of the query. We analyze the impact of caching the results of queries within the geographic zone from which the request was sourced, in terms of reduction of transactions with and bandwidth volume from the main server. We find that a cache document timeout even as low as 1024 seconds (about 17 minutes) during the two days that we analyzed would have saved between 40% and 70% of the bytes transferred from the central server. We investigate a range of timeouts for flushing documents from the cache, outlining the tradeoff between bandwidth savings and memory/cache management costs. We discuss the implications of this tradeoff in the face of possible future usage-based pricing of backbone services that may connect several cache sites. We also discuss other issues that caching inevitably poses, such as how to redirect queries initially destined for a central server to a preferred cache site. The preference of a cache site may be a function of not only geographic proximity, but also current load on nearby servers or network links. Such refinements in the web architecture will be essential to the stability of the network as the web continues to grow, and operational geographic analysis of queries to archive and library servers will be fundamental to its effective evolution.

Hans-Werner Braun

Papers

Application of sampling methodologies to network traffic characterization

Wireless Sensor Networks for Ecology

The NLANR Network Analysis Infrastructure

Traffic characteristics of the T1 NSFNET backbone

Web traffic characterization: an assessment of the impact of caching documents from NCSA's web server