In order for advanced applications in modern computer networks to function satisfactorily, there is often the need for a guaranteed network performance and guaranteed values for several network parameters. When the provisioning and usage of network services is agreed, relevant specifications for the level of the services are also defined.

The main focus of the book is the advances in telecommunications modeling, policy, and technology. In particular, several chapters of the book deal with low-level network layers and present issues in optical communication technology and optical networks, including the deployment of optical hardware devices and the design of optical network architecture. Wireless networking is also covered, with a focus on WiFi and WiMAX technologies. The book also contains chapters that deal with transport issues, and namely protocols and policies for efficient and guaranteed transmission characteristics while transferring demanding data applications such as video. Finally, the book includes chapters that focus on the delivery of applications through common telecommunication channels such as the earth atmosphere. This book is useful for researchers working in the telecommunications field, in order to read a compact gathering of some of the latest efforts in related areas. It is also useful for educators that wish to get an up-to-date glimpse of telecommunications research and present it in an easily understandable and concise way. It is finally suitable for the engineers and other interested people that would benefit from an overview of ideas, experiments, algorithms and techniques that are presented throughout the book.

Real-time protocols cover specific needs by applications with real-time characteristics. Real-time applications, such as voice over IP (VoIP), videoconferencing applications, video on demand, continuous data applications, and control and measurement applications have specific requirements from the lower layers, mainly in terms of packet loss, delay, and jitter. Traditional transport protocols such as TCP and UDP have been designed for general use and are not specialized for such specific purposes. In particular, real-time protocols have to be able to deliver high throughput, handle multicast, manage the transmission quality, and be friendly to the rest of the traffic, and, more importantly, to the congestion-sensitive TCP traffic.

DiffServ is the basis of contemporary QoS-enabled networks. Setting up DiffServ QoS requires extensive engineering effort in dimensioning and provisioning, especially for adjacent networks under different administrations linked in a 'federated' hierarchy. The bandwidth broker is an entity that is responsible for the management of the resources and the QoS service operation in an automated way. In this paper, we present, test and compare two different architectures of bandwidth brokers: a centralized one and a distributed one. We also deal with the inter-domain operation of the bandwidth broker in order to perform end-to-end provisioning. The paper presents the relevant aspects for inter-domain operation of a bandwidth broker and focuses on pathfinding issues. We discuss two models for inter-domain routing through bandwidth brokers, analyzing their advantages and comparing them.

This article provides a description of the IPv6 protocol. It briefly covers the reasons that make IPv6 a necessary upgrade, describes the most important methods for transitioning networks, applications, and hosts from IPv4 to IPv6, and the possibilities that IPv6 opens up. It finally also examines the current status of IPv6 deployment and vendor, protocol, and application support.

Deployment of IPv6 technology in research and commercial networks has accelerated in the last few years. Inevitably, as more advanced services take advantage of the new technology, IPv6 traffic gradually increases. Today, there is limited experience in the deployment of Quality of Service (QoS) for IPv6 traffic in backbone networks that support the Differentiated Services framework. As available software and hardware are designed to handle IPv4 packets, there is a need to accurately measure and validate performance of QoS mechanisms in an IPv6 environment. This paper discusses tests and technical challenges in the deployment of IPv6 QoS in core networks, namely the production dual stack gigabit‐speed Greek Research and Education Network (GRNET) and the IPv6‐only 6NET European test network, using both hardware and software platforms. In either case, we succeeded in delivering advanced transport services to IPv6 traffic and provided different performance guarantees to portions of traffic. The deployed QoS schema was common to IPv6 and IPv4; in most cases both v4 and v6 traffic exhibited comparable performance per class, while imposing no significantly different overhead on network elements. A major conclusion of our tests is that the IPv6 QoS mechanisms are efficiently supported with state‐of‐the‐art router cards at gigabit speeds. Copyright © 2008 John Wiley & Sons, Ltd.

IP networks are built around the idea of best effort networking, which makes no guarantees regarding the delivery, speed, and accuracy of the transmitted data. While this model is suitable for a large number of applications, and works well for almost all applications when the network load is low (and therefore there is no congestion), there are two main factors that lead to the need for an additional capability of quality of service guarantees. One is the fact that an increasing number of Internet applications are related to real-time and other multimedia data, which have greater service requirements in order to be satisfying to the user. The other is that Internet usage is steadily increasing, and although the network infrastructure is also updated often, it is not always certain that network resource offerings will be ahead of usage demand. In order to deal with this situation, IETF has developed two architectures in order to enable QoS-based handling of data flows in IP networks. This article describes and compares these two architectures.

The heterogeneous network environment that Internet provides to real time applications as well as the lack of sufficient QoS (Quality of Service) guarantees, many times forces applications to embody adaptation schemes in order to work efficiently. In addition, any application that transmits data over the Internet should have a friendly behaviour towards the other flows that coexist in today’s Internet and especially towards the TCP flows that comprise the majority of flows. We define as TCP friendly flow, a flow that consumes no more bandwidth than a TCP connection, which is traversing the same path with that flow (Pandhye 1999).

This paper presents some of the results obtained by the application of Ethernet layer 2 quality of service in IP networks. IP networks traditionally provide quality of service in Layer 3. However, since there is an enormous existing Layer 2 infrastructure, todaypsilas networks could benefit from the deployment of Layer 2 quality of service and the cooperation between layer 2 quality of service and layer 3 quality of service. In this paper, experiments are suggested and conducted and a scheme is suggested for efficient cooperation between Layer 2 and Layer 3 QoS provisioning.

This chapter presents the design principles that cover the implementation of broadband infrastructure in the region of Western Greece, by examining all the necessary parameters that arise while implementing such a critical developmental project. The broadband infrastructure that is deployed is either based on optical fiber (on big municipalities) or on wireless systems (OFDM based and WiFi cells). Furthermore, we present as two case studies, all issues of the designing of the Metropolitan Area Network of Patras, the third biggest city of Greece and the Wireless Access Network of Messatida. The major target of the broadband networks is to interconnect the buildings of the public sector in the city and also deploy infrastructure (fibers or wireless systems) that will create conditions of competition in providing both access and content services in advantage of the end consumer. The usage of the broadband infrastructure by service providers will be based on the open availability of the infrastructure in a cost effective way. Finally, we present the main characteristics of a proposed business plan that ensures financial viability of the broadband infrastructure and guarantees the administration, growth, and exploitation of infrastructure.

In this paper, we present work that we have carried out in extending the ns-2 simulator in order to study and validate Quality of Service issues and related architectures. In the case of the DiffServ framework, simulation is valuable since an analytical approach of mechanisms and services is infeasible due to the aggregation and multiplexing of flows. This paper covers work in extending ns-2 functionality towards the direction of realistic traffic generation and a series of mechanisms defined by the DiffServ architecture. We have also extended ns-2 with the functionality of Bandwidth Brokers, which are entities for managing the resources and negotiating end to end resource reservations between domains. The Bandwidth Broker ns-2 implementation is useful for studying the related architectures and admission control procedures.

This paper deals with the design and investigation of an approach for dynamic and on demand QoS on videoconference sessions for GRNET’s (Greek NREN) network. After the activation of QoS service in GRNET, a new need for automation of mechanisms for QoS in Videoconferencing session arises. The traditional QoS workflow inserts important administrative cost when a connected institute wants to have a videoconference service with specific QoS guaranties. In such case, the network administrator must manual configure the network’s edge routers. In order to overcome the above limitation, an “automatic” procedure for providing QoS guaranties to videoconference session was investigated. The result was an automatic solution that provides QoS using the QoS Policy Propagation via BGP mechanism for signaling. This automatic QoS deployment solution was tested successfully on the network and some performance measurement are presented in this paper.

This paper presents our work regarding the testing and evaluation of DiffServ QoS mechanisms over IPv6 and IPv4 in dual stack software based platforms. IPv6 introduces some additional features (like flow label) and the current support for QoS mechanisms in IPv6 implementations approaches the corresponding QoS support in IPv4. Therefore, a number of tests with DiffServ QoS mechanisms applied on IPv6 traffic have been carried out on a testbed created specifically for this purpose, in order to validate the mechanisms and evaluate the router's overall performance. Our evaluations cover the load incurred to the routing devices from the implementation of the mechanisms, the level of support for QoS IPv6 features and the comparison of performance over IPv4 and IPv6.

This paper deals with a distributed bandwidth broker that we try to extend in order to perform inter-domain operation. The basic issues for inter-domain operation are discussed and we try to approach the most demanding issues as the selection of the best inter domain routing path. Generally, we discuss three models for inter domain routing through bandwidth broker, analyzing their advantages. Also, a very important point that affects the interdomain operation is the SLAs between adjacent domains and the capability that a bandwidth broker should have to ask and perform dynamic negotiation. Finally, we analyze the best model and present how it should be incorporated in the existing distributed implementation.

In this paper we present and compare four different models of implementing a Bandwidth Broker in a DiffServ network. We describe the relevant implementation aspects in the well-known ns-2 simulator and present a number of experiments that were conducted in order to verify our implementation, analyze the performance characteristics of the various alternatives and evaluate the usefulness of the ns-2 simulation environment for similar purposes. We present our experiments that aim at investigating a number of issues related to the operation of Bandwidth Broker modules, and in particular how the acceptance rate, the network overhead and the response time for each Bandwidth Broker model are affected by the network topology, the available buffers for incoming requests and the advance time from the moment a request is submitted to the moment the reservation should take place

This paper presents the design principles that cover the implementation of broadband infrastructure in the region of Western Greece, by examining all the necessary parameters that arise while implementing such a critical developmental project. Furthermore, we present as a case study, all issues of the designing of the Metropolitan Area Network of Patras, the third biggest city of Greece. The major target of the MAN of Patras is to interconnect the buildings of the public sector in the city and also deploy fibers that will create conditions of competition in providing both access and content services in advantage of the end consumer. The usage of the broadband infrastructure by service providers will be based on the open availability of the fiber optics infrastructure in a cost effective way. Finally, we present the main characteristics of a proposed business plan that ensures financial viability of the broadband infrastructure.

This paper gives an overview of the issues related to the QoS mechanisms under IPv6 and the transition of applications to the new Internet protocol. We describe the implementation and testing of a QoS service on IPv6 networks, which is based on the DiffServ architecture (expedited forwarding) and provides strict priorities to packets that are produced from real time applications. The service was implemented and tested at the 6NET large-scale IPv6 network, and additional advanced testing was performed in a local testbed. We present and analyze the results from our tests under a number of different scenarios. In addition, we focus on issues regarding application transition to IPv6 and we briefly discuss as a case study the transition of OpenH323 protocol stack to support IPv6. We also discuss the usage and the expected impact of the new Flow Label field in the IPv6 header.

This paper deals with bandwidth brokers and their inter-domain operation. The basic issues for inter-domain operation are discussed and we try to approach the most demanding issues as the selection of the best inter domain routing path (pathfinding). Generally, we discuss two models for inter domain routing through bandwidth broker, analyzing their advantages and comparing them. Also, we simulated the second one (generalized distributed pathfinding) trying to evaluate its performance. Finally, we discuss the simulation's results and present how this model should be incorporated in normal operation routing of commercial ISPs or academic networks that works on a federated way