Quality of service on the internet: evaluation of RSVP based solutions.

The Internet represents nowadays the most important communication medium used by billions of persons around the globe. One of the problems associated with the evolution of the Internet is that since the beginning it was conceived as a best-effort service delivery model. However, this model was transformed over time. The alteration of the Internet best-effort service delivery model is a direct consequence of the introduction of real-time services that are sensitive to Quality of Service (QoS) parameters. This dissertation starts by analyzing the current service delivery models that exist in the Internet (Chapter 1), covering also the motivation that triggered the introduction of each model separately. Subsequently, a special focus is given to the Resource Reservation Protocol (RSVP). RSVP represents one of the most important protocols used for resource reservation in the Internet. A thorough analysis of the evolution of RSVP is presented in Chapter 2. Throughout this thesis, simulation will be used to analyze, evaluate, and test different propositions that relate in one way or another with RSVP. OPNET Modeler represents the network simulation tool that was used in this context. Some details about how OPNET functions, what are the main characteristics of this simulation tool, how protocols can be altered or implemented, and how RSVP is implemented in OPNET Modeler are illustrated in Chapter 4. Chapter 5 concentrates on evaluating the impact of employing admission control by using RSVP as a capacity admission strategy in one of the service delivery models (the Differentiated Service mechanism). In this context, a new service delivery model for the Internet is proposed: the two-stage service differentiation model (tsSDM). One of the main issues associated with RSVP is the scalability problem of the protocol. Running RSVP requires resources, in terms of processing power and memory space. For each established reservation of a particular session RSVP messages have to be generated, transmitted, and processed within a certain period. In Chapters 6 and 7, this scalability problem of RSVP comes into focus. In Chapter 6, the main requirements and the most important technical aspects that need to be taken into consideration in order to implement the Bundle extension and respectively the Summary Refresh extension in OPNET Modeler are presented. Moreover, a quantifiable measure of the scalability of RSVP and of the two associated extensions is offered, based on the execution overhead introduced by the protocol. Chapter 7 continues the work on the scalability of RSVP by evaluating the performance of the RSVP Aggregation extension. Proposed as an alteration of the original protocol design, the Aggregation extension was introduced in order to address the scalability problem of the protocol. Practical considerations and key design choices made during the implementation process are illustrated in this chapter. Furthermore, the scalability and the QoS that can be obtained by using this alteration of RSVP are analyzed.nrpages: 303status: publishe