Abstract

Constraint-based routing (CR-LDP) extends the features of MPLS Label Distribution Protocol (LDP) working in conjunction with a wide variety of QoS scenarios and services including IP differentiated services, integrated services, traffic engineering, Asynchronous Transfer Mode (ATM) service classes and frame relay. When a large number of CR-LSPs are required a lot of CR-LDP signalling is needed: this paper proposes two techniques — caching and aggregation — to reduce the number of CR-LDP messages by dynamically increasing the number of flows served by each single CR-LSP. The results of a simulation are also used to discuss the performance of such mechanisms. Document type: Part of book or chapter of book

Abstract

Today, Internet technologies have pervaded every corner of our society. More and more people are benefiting from the Internet in one way or the other. One of the current Internet technologies that may benefit us greatly is voice over Internet protocol (VoIP). According to Hardy (2003, p. 2), VoIP is “the interactive voice exchange capability carried over packet-switched transport employing the Internet protocol.” With VoIP technology, one can call anyone in this world at a lower cost, compared to traditional telephone systems. However, VoIP technology has one significant drawback. It has a low degree of reliability. From experimental results it is known that VoIP can achieve only 98% reliability. The service down time per year for VoIP is almost 20 working days (175 hours). For most companies and government organizations, such a degree of reliability is unacceptable since the traditional telephone system can achieve 99.999% reliability with a service down time of only five minutes per year (Kos, Klepec, & Tomaxic, 2005). As a result, quality of service (QoS) is an important concept for VoIP. Using QoS, VoIP may be able to overcome its limitation in reliability. QoS is often defined as the capability to provide resource assurance and service differentiation in a network. The definition includes two important terms—resource assurance and service differentiation. Resource assurance provides a guarantee about the amount of network resources requested by the user. On the other hand, service differentiation provides higher priority of getting network resources to those applications that have critical latency constraints. Given the importance of low latency for voice communication, it is not difficult to predict that QoS will assume greater importance in the VoIP industry as this technology gains popularity in the mass market. It is reported that VoIP is aggressively growing, and this growth is expected to continue in the coming years. Document type: Part of book or chapter of book

Abstract

The evolution of Internet and its successful technologies has brought a tremendous growth in business, education, research etc. over the last four decades. With the dramatic advances in multimedia technologies and the increasing popularity of real-time applications, recently Quality of Service (QoS) support in the Internet has been in great demand. Deployment of such applications over the Internet in recent years, and the trend to manage them efficiently with a desired QoS in mind, researchers have been trying for a major shift from its Best Effort (BE) model to a service oriented model. Such efforts have resulted in Integrated Services (Intserv), Differentiated Services (Diffserv), Multi Protocol Label Switching (MPLS), Policy Based Networking (PBN) and many more technologies. But the reality is that such models have been implemented only in certain areas in the Internet not everywhere and many of them also faces scalability problem while dealing with huge number of traffic flows with varied priority levels in the Internet. As a result, an architecture addressing scalability problem and satisfying end-to-end QoS still remains a big issue in the Internet. In this chapter the authors propose a policy based architecture which they believe can achieve scalability while offering end to end QoS in the Internet. Document type: Part of book or chapter of book