A Method for Evaluation of Qualityof Service in Computer Networks
Tomasz Bujlow, Sara Ligaard Nørgaard Hald, Tahir Riaz, Jens Myrup Pedersen
Section for Networking and Security, Department of Electronic Systems
Aalborg University, DK-9220, Aalborg East, Denmark
tbu@es.aau.dk, slh@es.aau.dk, tahir@es.aau.dk, jens@es.aau.dk

Abstract— Monitoring of Quality of Service (QoS) in highspeed Internet infrastructures is a challenging task. However, precise assessments
must take into account the fact that the requirements for the given quality level are service-dependent. The backbone QoS monitoring and analysis
requires processing of large amounts of data and knowledge of which kinds of applications the traffic is generated by. To overcome the drawbacksof existing methods for traffic classification, we proposed and evaluated a centralized solution based on the C5.0 Machine Learning Algorithm(MLA) and decision rules. The first task was to collect and to provide to C5.0 high-quality training data divided into groups, which correspond todifferent types of applications. It was found that the currently existing means of collecting data (classification by ports, Deep Packet Inspection,statistical classification, public data sources) are not sufficient and they do not comply with the required standards. We developed a new system tocollect training data, in which the major role is performed by volunteers. Client applications installed on volunteers’ computers collect thedetailed data about each flow passing through the network interface, together with the application name taken from the description of system
sockets. This paper proposes a new method for measuring the level of Quality of Service in broadband networks. It is based on ourVolunteer-Based System to collect the training data, Machine Learning Algorithms to generate the classification rules and theapplication-specific rules for assessing the QoS level. We combine both passive and active monitoring technologies. The paper evaluates different
possibilities of implementation, presents the current implementation of particular parts of the system, their initial runs and the obtained results,
highlighting parts relevant from the QoS point of view.
Keyword—broadband networks, data collecting, Machine Learning Algorithms, performance monitoring, Quality of Service, trafficclassification, volunteer-based system
Tomasz Bujlow is working as a Ph.D. Student in the Section for Networking and Security (NetSec) in the Department of Electronic Systems atAalborg University in Denmark. He received his Master of Science in Computer Engineering from Silesian University of Technology in Polandin 2008, specializing in Databases, Computer Networks and Computer Systems. Previously, he obtained his Bachelor of Computer Engineeringfrom University of Southern Denmark in 2009, specializing in software engineering and system integration. His research interests include
methods for measurement of Quality of Service and traffic classification in computer networks. He is also a Cisco Certified Network
Professional (CCNP) since 2010

Sara Ligaard Nørgaard Hald is working as a Ph.D. student in the Section for Networking and Security (NetSec) in the Department ofElectronic Systems at Aalborg University in Denmark. She received her Master of Science in Computer Engineering and Management fromAalborg University in 2002, and has since worked for the Danish Defense and as a consultant specializing in enterprise architecture andcybersecurity. Research interests include threat assessments and attack detection in dedicated networks.

Tahir Riaz is working as an Assistant Professor in the Section for Networking and Security (NetSec) in the Department of Electronic Systems
at Aalborg University in Denmark. He received his Master and PhD degrees in Electrical and Electronics Engineering, specializing in Network
Planning and Management, from Aalborg University in 2004 and 2008, respectively. He has also worked in Nokia, Linkoping, Sweden. He has
authored or coauthored over 70 papers published in conferences and journals. His research interests include access and backbone fiber optic
networks, network planning and design, architecture of next generation radio of fiber networks, reliability and QoS issues in largescale accessand core network infrastructures, performance and optimization in networks.

Jens Myrup Pedersen is working as an Associate Professor and the head of the Section for Networking and Security (NetSec) in theDepartment of Electronic Systems at Aalborg University. His current research interests include network planning, traffic monitoring, andnetwork security. He obtained his Master of Science in Mathematics and Computer Science from Aalborg University in 2002, and his PhD in
Electrical Engineering also from Aalborg University in 2005. He is an author/co-author of more than 70 publications in international
conferences and journals, and has participated in Danish, Nordic and European funded research projects. He is also a board member of a numberof companies within technology and innovation.