Latency and player actions in online games

The growth and penetration of broadband access networks to the home has fueled the growth of online games played over the Internet. As we write this article, it is 5am on a typical weekday morning and Gamespy Arcade 1 reports more than 250,000 players online playing about 75,000 games! This proliferation of online games has been matched by an equivalent growth in both th

Minimally-intrusive frequent round trip time measurements using Synthetic Packet-Pairs

Accurate and frequent round trip time (RTT) measurements are important in testbeds and operational networks. Active measurement techniques inject probe packets that may modify the behaviour of the observed network and may produce misleading RTT estimates if the network handles probe packets differently to regular packets. Previous passive measurement techniques address these issues, but require precise time synchronisation or are limited to certain traffic types. We introduce Synthetic Packet-Pairs (SPP), a novel passive technique for RTT measurement. SPP provides frequently updated RTT measurements using any network traffic already present in the network without the need for time synchronisation. SPP accurately measures the RTT experienced by any application's traffic, even applications that do not exhibit symmetric client-server packet exchanges. We experimentally demonstrate the advantages of SPP

An Overview of Internet Measurements:Fundamentals, Techniques, and Trends

The Internet presents great challenges to the characterization of its structure and behavior. Different reasons contribute to this situation, including a huge user community, a large range of applications, equipment heterogeneity, distributed administration, vast geographic coverage, and the dynamism that are typical of the current Internet. In order to deal with these challenges, several measurement-based approaches have been recently proposed to estimate and better understand the behavior, dynamics, and properties of the Internet. The set of these measurement-based techniques composes the Internet Measurements area of research. This overview paper covers the Internet Measurements area by presenting measurement-based tools and methods that directly influence other conventional areas, such as network design and planning, traffic engineering, quality of service, and network management

Automated Inference System for End-To-End Diagnosis of Network Performance Issues in Client-Terminal Devices

Traditional network diagnosis methods of Client-Terminal Device (CTD) problems tend to be laborintensive, time consuming, and contribute to increased customer dissatisfaction. In this paper, we propose an automated solution for rapidly diagnose the root causes of network performance issues in CTD. Based on a new intelligent inference technique, we create the Intelligent Automated Client Diagnostic (IACD) system, which only relies on collection of Transmission Control Protocol (TCP) packet traces. Using soft-margin Support Vector Machine (SVM) classifiers, the system (i) distinguishes link problems from client problems and (ii) identifies characteristics unique to the specific fault to report the root cause. The modular design of the system enables support for new access link and fault types. Experimental evaluation demonstrated the capability of the IACD system to distinguish between faulty and healthy links and to diagnose the client faults with 98% accuracy. The system can perform fault diagnosis independent of the user's specific TCP implementation, enabling diagnosis of diverse range of client devicesComment: arXiv admin note: substantial text overlap with arXiv:1207.356

Gaining insight into AS-level outages through analysis of internet background radiation

Abstract—Internet Background Radiation (IBR) is unsolicited network traffic mostly generated by malicious software, e.g., worms, scans. In previous work, we extracted a signal from IBR traffic arriving at a large (/8) segment of unassigned IPv4 address space to identify large-scale disruptions of connectivity at an Autonomous System (AS) granularity, and used our technique to study episodes of government censorship and natural disasters [1]. Here we explore other IBR-derived metrics that may provide insights into the causes of macroscopic connectivity disruptions. We propose metrics indicating packet loss (e.g., due to link congestion) along a path from a specific AS to our observation point. We use three case studies to illustrate how our metrics can help identify packet loss characteristics of an outage. These metrics could be used in the diagnostic component of a semi-automated system for detecting and characterizing large-scale outages. I

On combining temporal scaling and quality scaling for streaming MPEG

Temporal Scaling and Quality Scaling are both widely-used techniques to reduce the bitrate of streaming video. How-ever, combinations and comparisons of Temporal and Qual-ity Scaling have not been systematically studied. This re-search extends previous work to provide a model for combin-ing Temporal and Quality Scaling, and uses an optimization algorithm to provide a systematic analysis of their combina-tion over a range of network conditions and video content. Analytic experiments show: 1) Quality Scaling typically per-forms better than Temporal Scaling, with performance dif-ferences correlated with the motion characteristics of the video. In fact, when the network capacity is moderate and the loss rate is low, Quality Scaling performs nearly as well as the optimal combination of Quality and Temporal Scal-ing; 2) when the network capacity is low and the packet loss rate is high, Quality Scaling alone is ineffective, but a combination of Quality and Temporal Scaling can provide reasonable video quality; 3) adjusting the amount of For-ward Error Correction (FEC) provides significantly better performance than video streaming without FEC or video streaming with a fixed amount of FEC. 1

Trading link utilization for queueing delays: an adaptive approach

Understanding the relationship between queueing delays and link utilization for general traffic conditions is an important open problem in networking research. Difficulties in understanding this relationship stem from the fact that it depends on the complex nature of arriving traffic and the problems associated with modelling such traffic. Existing AQM schemes achieve a "low delay" and "high utilization" by responding early to congestion without considering the exact relationship between delay and utilization. However, in the context of exploiting the delay/utilization tradeoff, the optimal choice of a queueing scheme's control parameter depends on the cost associated with the relative importance of queueing delay and utilization. The optimal choice of control parameter is the one that maximizes a benefit that can be defined as the difference between utilization and cost associated with queuing delay. We present two practical algorithms, Optimal Drop-Tail (ODT) and Optimal BLUE (OB), that are designed with a common performance goal: namely, maximizing this benefit. Their novelty lies in fact that they maximize the benefit in an online manner, without requiring knowledge of the traffic conditions, specific delay-utilization models, nor do they require complex parameter estimation. Packet level ns2 simulations are given to demonstrate the efficacy of the proposed algorithms and the framework in which they are designed