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2013 QUALITY OF SERVICE AND INFOCOMMUNICATIONS MANAGEMENT (QoS-ICM) Elite Masters Degree Course Lecture 1– Introduction into the QM-IC. The quality of service (QoS) refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements. In particular, much technology has been developed to allow computer networks to become as useful as telephone networks for audio conversations, as well as supporting new applications with even stricter service demands. In the field of telephony, quality of service was defined by the ITU in 1994.[1] Quality of service comprises requirements on all the aspects of a connection, such as service response time, loss, signal-to-noise ratio, cross-talk, echo, interrupts, frequency response, loudness levels, and so on. A subset of telephony QoS is grade of service (GoS) requirements, which comprises aspects of a connection relating to capacity and coverage of a network, for example guaranteed maximum blocking probability and outage probability.[2] In the field of computer networking and other packet-switched telecommunication networks, the traffic engineering term refers to resource reservation control mechanisms rather than the achieved service quality. Quality of service is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow. For example, a required bit rate, delay, jitter, packet dropping probability and/or bit error rate may be guaranteed. Quality of service guarantees are important if the network capacity is insufficient, especially for real-time streaming multimedia applications such as voice over IP, online games and IP-TV, since these often require fixed bit rate and are delay sensitive, and in networks where the capacity is a limited resource, for example in cellular data communication. A network or protocol that supports QoS may agree on a traffic contractwith the application software and reserve capacity in the network nodes, for example during a session establishment phase. During the session it may monitor the achieved level of performance, for example the data rate and delay, and dynamically control scheduling priorities in the network nodes. It may release the reserved capacity during a tear down phase. A best-effort network or service does not support quality of service. An alternative to complex QoS control mechanisms is to provide high quality communication over a best-effort network by over-provisioning the capacity so that it is sufficient for the expected peak traffic load. The resulting absence of network congestion eliminates the need for QoS mechanisms. QoS is sometimes used as a quality measure, with many alternative definitions, rather than referring to the ability to reserve resources. Quality of service sometimes refers to the level of quality of service, i.e. the guaranteed service quality. High QoS is often confused with a high level of performance or achieved service quality, for example high bit rate, lowlatency and low bit error probability. An alternative and disputable definition of QoS, used especially in application layer services such as telephony and streaming video, is requirements on a metric that reflects or predicts the subjectively experienced quality. In this context, QoS is the acceptable cumulative effect on subscriber satisfaction of all imperfections affecting the service. Other terms with similar meaning are the quality of experience (QoE) subjective business concept, the required “user perceived performance”,[3] the required “degree of satisfaction of the user” or the targeted “number of happy customers”. Examples of measures and measurement methods are Mean Opinion Score (MOS), Perceptual Speech Quality Measure (PSQM) and Perceptual Evaluation of Video Quality (PEVQ). See also subjective video quality. Conventional Internet routers and LAN switches operate on a best effortbasis. This equipment is less expensive, less complex and faster and thus more popular than competing more complex technologies that provided QoS mechanisms. There were four “Type of service” bits and three “Precedence” bits provided in each IP packet header, but they were not generally respected. These bits were later redefined as DiffServ Code Points (DSCP) and are sometimes honored in peered links on the modern Internet. With the advent of IPTV and IP telephony, QoS mechanisms are increasingly available to the end user. References 1. "E.800: Terms and definitions related to quality of service and network performance including dependability". ITU-T Recommendation. August 1994. Retrieved October 14, 2011. Updated September 2008 as Definitions of terms related to quality of service 2. Teletraffic Engineering Handbook ITU-T Study Group 2 (350 pages, 4·48MiB)(It uses abbreviation GoS instead of QoS) 3. Leonard Franken. Quality of Service Management: A Model-Based Approach. PhD thesis, Centre for Telematics and Information Technology, 1996. 4. Peuhkuri M., IP Quality of Service, Helsinki University of Technology, Laboratory of Telecommunications Technology, 1999. 5. Yuksel, M.; Ramakrishnan, K. K.; Kalyanaraman, S.; Houle, J. D.; Sadhvani, R. (2007). "Value of Supporting Class-of-Service in IP Backbones" (PDF). IEEE International Workshop on Quality of Service (IWQoS'07). Evanston, IL, USA. pp. 109–112.doi:10.1109/IWQOS.2007.376555. ISBN 1-4244-1185-8. 6. An Evening With Robert Kahn, from Computer History Museum, 9 Jan 2007 7. Bianchi, Giuseppe (2000). "Performance analysis of the IEEE 802.11 distributed coordination function". IEEE Journal on Selected Areas in Communications 18 (3): 535. doi:10.1109/49.840210. 8. Shi, Zhefu; Beard, Cory; Mitchell, Ken (2009). "Analytical Models for Understanding Misbehavior and MAC Friendliness in CSMA Networks".Performance Evaluation 66 (9–10): 469. doi:10.1016/j.peva.2009.02.002. 9. Ben Erwin (December 16, 2008). "How To Manage QoS In Your Environment, Part 1 of 3". Network Performance Daily video. NetQoS. Retrieved October 15, 2011. 10. "VoIP on MPLS". Search Unified Communications. Retrieved 12 March 2012. 11. Bob Braden ed. L. Zhang, S. Berson, S. Herzog, S. Jamin (September 1997). "Resource ReSerVation Protocol (RSVP)". RFC 2205. IETF. Retrieved October 12, 2011. 12. “Next Steps in Signaling” Charter 13."EuQoS - End-to-end Quality of Service support over heterogeneous networks". Project website. 2004–2006. Archived from the original on April 30, 2007. Retrieved October 12, 2011. 14. IPSphere: Enabling Advanced Service Delivery 15. "End-to-end quality of service support over heterogeneous networks".Project description. European Community Research and Development Information Service. Retrieved October 12, 2011. 16.Torsten Braun; Thomas Staub (2008). End-to-end quality of service over heterogeneous networks. Springer. ISBN 978-3-540-79119-5. 17. "Multi Service Access Everywhere (MUSE)". Project website. Retrieved October 12, 2011. 18. "Multi Service Access Everywhere". Project description. European Community Research and Development Information Service. Retrieved October 12, 2011. 19.^ "Multi Service Access Everywhere". Project description. European Community Research and Development Information Service. Retrieved October 12, 2011. 20."PlaNetS QoS Solution". Project website. Archived from the originalon November 12, 2009. Retrieved October 12, 2011. 21."4WARD: Architecture and design for the future Internet". Project description. European Community Research and Development Information Service. Retrieved October 15, 2011. 22."Going 4WARD" (PDF). Project newsletter. June 2010. Retrieved October 15, 2011. 23.Luís M. Correia; Joao Schwarz (FRW) da Silva (January 30, 2011).Architecture and Design for the Future Internet: 4WARD EU Project. Springer. ISBN 978-90-481-9345-5. 24."Wireless Deployable Network System". Project description. European Union. Retrieved May 23, 2012. 25.R. Guimaraes, L. Cerdà, J. M. Barcelo-Ordinas, J. Garcia-Vidal, M. Voorhaen, C. Blondia (March 2009). "Quality of Service through Bandwidth Reservation on Multirate Ad-doc Wireless Networks". Ad Hoc Networks Journal (Elsevier), Vol. 7, Issue 2 7 (2): 388–400.doi:10.1016/j.adhoc.2008.04.002. 26.D. Kyriazis, K. Tserpes, A. Menychtas, A. Litke, T. Varvarigou, An innovative Workflow Mapping Mechanism for Grids in the frame of Quality of Service, Elsevier Future Generation Computer Systems, Vol. 24, Iss. 6, pp. 498-511, 2008 27.Q. Sun, S. Wang, H. Zou, F. Yang, QSSA: A QoS-aware Service Selection Approach, International Journal of Web and Grid Services, pp.147 - 169, 2011 28.D Kyriazis, A Menychtas, G Kousiouris, K Oberle, T Voith, M Boniface, E Oliveros, T Cucinotta, S Berger, “A Real-time Service Oriented Infrastructure”, International Conference on Real-Time and Embedded Systems (RTES 2010), Singapore, November 2010 29.Benjamin Teitelbaum, Stanislav Shalunov (May 3, 2002). "Why Premium IP Service Has Not Deployed (and Probably Never Will)". Draft Informational Document. Internet2 QoS Working Group. Archived from the original on September 12, 2010. Retrieved October 15, 2011. 30.Andy Oram (June 11, 2002). "A Nice Way to Get Network Quality of Service?". Platform Independent column. O'Reilly. Archived from the original on September 12, 2010. Retrieved October 15, 2011. 31.Gary Bachula (February 7, 2006). "Testimony of Gary R. Bachula, Vice President, Internet2". pp. 2–3. Retrieved October 15, 2011. 32. "X.902:Information technology – Open Distributed Processing – Reference model: Foundations". ITU-T Recommendation. November 1995. Retrieved October 14, 2011. Updated October 2009. 33."X.641: Information technology - Quality of service: framework". ITU-T Recommendation. December 1997. 34."Advanced Routing & Traffic Control HOWTO". August 21, 2005. Retrieved October 14, 2011. 35."Linux Bandwidth Arbitrator". APConnections. Retrieved October 14, 2011. 36.Fulvio Ricciardi. "QoS and Traffic Shaping in Transparent Bridge mode".Router/Bridge Linux Firewall website. ZeroShell Net Services. Retrieved October 15, 2011.