DiffServ

This paper discusses the issue of how to obtain Quality of Service (QoS) for the new applications (Multimedia, VoIP, ...) over IP networks. QoS principles and parameters (Delay, jitter, ...) are discussed together with the architectures, frameworks, protocols and mechanisms being proposed for obtaining a guaranteed application support over the Internet and private IP networks.

Essa dissertação propõe e avalia uma arquitetura de suporte de Qualidade de Serviço para aplicações de Telemedicina, com suporte ao uso concorrente de Vídeo sob Demanda e Videoconferência sobre uma infra-estrutura de rede IP. A arquitetura de Qualidade de Serviço (QoS - Quality of Service) considerada é o DiffServ (Differentiated Services) proposta pelo IETF (Internet Engineering Task Force). Em particular, este estudo propõe a utilização de um elemento gerenciador de políticas de QoS – o Bandwidth Broker – que recebe solicitações de alocação dinâmica de recursos das aplicações de Vídeo sob Demanda e Videoconferência, valida as solicitações contra contratos de níveis de serviço (SLAs - Service Level Agreements) acordados, e aloca recursos através de distribuição de configuração de mecanismos DiffServ em dispositivos de roteamento na rede.
Esse trabalho especifica uma solução de integração da rede de vídeo digital a um elemento gerenciador de políticas ao nível de plano de controle – o Bandwidth Broker, de forma a permitir o gerenciamento dinâmico de recursos baseado em políticas. Especifica e prototipa, ainda, uma infra-estrutura de suporte para configurações, fazendo uso de plataformas Linux, e valida resultados de implementação de mecanismos de Qualidade de Serviço DiffServ. Para este fim são considerados diferentes cenários que simulam o uso das aplicações do Projeto InfraVIDA – um projeto de telemedicina que integra serviços de Telediagnóstico e Segunda Opinião Médica, baseados na Internet.
Uma avaliação das tendências de evolução do campo de gerenciamento de Qualidade de Serviço em redes IP baseado em políticas complementa esse estudo.

Internet Service Provider (ISP). SCIS adopts the wireless broadband last mile access as an inexpensive solution, in order to compromise cost, high demand, and Quality of Service (QoS) factors. SCIS has WiFi and WiMAX networks for last mile access. In this work the existing WiFi and WiMAX networks of SCIS are modeled using OPNET modeler. The modeled networks are extensively analysed to investigate their performance for several types of delay sensitive and delay insensitive applications. These applications are Voice over Internet Protocol (VoIP), video streaming, File Transfer Protocol (FTP), and Hyper Text Transfer Protocol (HTTP). The performance of the modeled existing networks is evaluated in terms of several evaluating criteria; these are Delay, Jitter, Download Response Time, Page Response Time, and Throughput. All analyses are performed under the impact of free space propagation model. Accordingly, proposed modifications to existing modeled networks, to improve their performance, are presented in this work. For both WiFi and WiMAX networks, End-to-End QoS Mapping (E2EQM) schemes are applied. E2EQM scheme works based on internetworking between Differentiated Services (DiffServ); which is a layer three QoS architecture technique, and the QoS technique which is supported either by WiFi or by WiMAX. Decreased delay of 44 % and increased throughput of 5 % for SCIS WiFi network overall performance improvements are obtained. While for SCIS WiMAX network, a decreased delay of 45 % and increased throughput of 14 % are obtained as overall performance improvements. Other performance improvements are also obtained for both networks when II applying the E2EQM scheme after comprehensive analyses and comparisons being performed. Moreover, the improved WiMAX network is proposed for further modification to enhance its performance under increased demand circumstances. The modification is performed by adopting 10 MHz bandwidth instead of 5 MHz that is already used. This modification shows increased enhancement for the overall performance of the proposed network.

Se realiza un análisis del entorno de Calidad de Servicio actual, para identificar como se puede aplicar en la red más grande que es Internet. El documento se encuentra dividido en dos partes: en la primera de ellas se hace una revisión rápida de conceptos básicos de QoS como Arquitecturas, Mecanismos de Encolamiento y Algoritmos de Regulación de Velocidad; necesarios para entender la segunda parte. En la segunda parte se hace un seguimiento del artículo “Teorías y Modelos para Calidad de Servicio en Internet”, donde se analizan conceptos modernos como Network Calculus y la propuesta de Ion Stoica para un Stateless Core; si es conocedor del tema, podría iniciarse directamente por aquí. El objetivo final del documento es bajar la teoría general de QoS a un nivel más comprensible.

The Internet has become a universal communication network tool. It has evolved from a platform that supports best-effort traffic to one that now carries different traffic types including those involving continuous media with Quality of Service (QoS) requirements. As more services are delivered over the Internet, we face increasing risk to their availability given that malicious attacks on those Internet services continue to increase. Several networks have witnessed Denial of Service (DoS) and Distributed Denial of Service (DDoS) attacks over the past few years which have disrupted QoS of network services, thereby violating the Service Level Agreement (SLA) between the client and the Internet Service Provider (ISP). Hence DoS or DDoS attacks are major threats to network QoS. In this paper we survey techniques and solutions that have been deployed to thwart DoS and DDoS attacks and we evaluate them in terms of their impact on network QoS for Internet services. We also present vulnerabilities that can be exploited for QoS protocols and also affect QoS if exploited. In addition, we also highlight challenges that still need to be addressed to achieve end-to-end QoS with recently proposed DoS/DDoS solutions.

The past few years have witnessed the emergence of many real-time networked applications on the Internet. These types of applications require special support from the underlying network such as reliability, timeliness, and guaranteed delivery, as well as different levels of ...

Combining Integrated Services ([1], ) QoS mechanisms for end-to-end signaling at hosts and Differentiated Services ([2], ) QoS mechanisms in the network core is one proposal for overcoming the limitation of either mechanisms when applied alone ([8]). In this paper some of the open issues in [8] are discussed and a concrete proposal is presented, which maps the IntServ Controlled Load Service into the DiffServ Expedited Forwarding "Per Hop Behavior". The proposed approach has been implemented under the Linux Operating System. The implementation allows verifying the correct functional behavior and provides a platform where more complete performance tests are possible.

Abstract—With the expansion of Internet, the current protocol address space (IPv4) is faced with a shortage and the new generation Internet (IPv6) is raised in order to solve this problem. Also with increasing interest of users in real-time and multimedia applications, the Internet and how to implement these applications to improve the quality of service (QoS) has become a significant challenge. In this paper, a network with both IPv4 and IPv6 protocols is simulated by using OPNET Modeler and implementation of QoS is tested on it. Packet loss, end-to-end delay and jitter were evaluated as network performance metrics. The results showed that satisfying the needs of multimedia applications on IPv6 are slightly weaker than IPv4, but the benefits have evolved more and more and the difference is negligible. Also according to the methods used in terms of this study, the combination of DiffServ and MPLS QoS implementation is the best option for both Internet Protocol versions.

We present AntNet-QoS, a novel approach that taking inspiration from the Ant Colony Optimization (ACO) framework, and in particular from the AntNet routing algorithm, allows dynamic scheduling, forwarding and link sharing among multiple packet classes in a differentiated service (DiffServ) network.

In this paper, a cross-layer architecture (QoSatAr) is developed to provide end-to-end quality of service (QoS) guarantees for Internet protocol (IP) traffic over the Digital Video Broadcasting-Second generation (DVB-S2) satellite systems. The architecture design is based on a cross-layer optimization between the physical layer and the network layer to provide QoS provisioning based on the bandwidth availability present in the DVB-S2 satellite channel. One of the most important aspects of the architecture design is that QoSatAr is able to guarantee the QoS requirements for specific traffic flows considering a single parameter: the bandwidth availability which is set at the physical layer (considering adaptive code and modulation adaptation) and sent to the network layer by means of a cross-layer optimization. The architecture has been evaluated using the NS-2 simulator.

Network Mobility Basic Support (NEMO BS) protocol (RFC 3963) is an extension of Mobile IPv6. The NEMO BS embraced by IETF working group to permit any node in the portable network to be accessible to the Internet despite the fact the network itself is roaming. This protocol likewise Mobile IPv6 doesn't deliver any kind of Quality of Service (QoS) guarantees to its clients. It can barely offer the same level of services (i.e. Best-Effort) to all the users without obligation to the application's needs. This propositions a challenge to real-time applications that demand a precise level of QoS pledge. The Differentiated Services has recently come to be the most widely used QoS support technology in IP networks due to its relative simplicity and scalability benefits. This paper proposes a new scheme to provide QoS to mobile network nodes within NEMO context. The proposed scheme intends to reduce handover latency for the users of MNN as well as alleviates packet losses. The feasibility of the proposed enhancement is assessed by measuring its performance against the native NEMO BS standard protocol using NS-2 simulator. The obtained results in the simulation study have demonstrated that the proposed scheme outperforms the standard NEMO BS protocol.

This work proposes a hybrid solution, called the smart box architecture (SBoX), that provides quality of service (QoS) in internet protocol (IP)-based networks. SBoX architecture consists of SBoX servers, which are located at the network boundary, and SBoX routers, which are add-on label switching routers (LSR), which are located at interior network nodes. This approach combines the advantages of three existing technologies: integrated services (Intserv), dierentiated services (Diserv), and multi-protocol label switching (MPLS). SBoX aggregates trac in three levels: commodity-¯ows, macro-¯ows and micro-¯ows. Commodity-¯ows aggregate¯ow between every pair of edge points. The packets of the same commodity-¯ow are marked by an MPLS label. Commodity-¯ows are composed of macro-¯ows, which aggregate the trac of a particular enterprise. Macro-¯ows are associated with an explicit service level agreement (SLA), which is oered to users. Macro-¯ows are composed of micro-¯ows, which are the trac associated with a particular individual in an enterprise or a particular application. SBoX servers provide Diserv like SLA to users, and use class-based queuing (CBQ) with a hierarchy of¯ow aggregation. SBoX servers manage macro-¯ows and commodity-¯ows only, and leave the management of micro-¯ows to the enterprise/users which signed the SLA for the macro-¯ow. SBoX routers perform MPLS routing of commodity-¯ows in interior network nodes. SBoX routers can be combined with existing best-eort routers to provide QoS in a network that lacks end-to-end deployment of LSRs. This paper describes the SBoX architecture and its operation in detail. It also reports experimental results obtained on a prototype network. The results indicate that the SBoX architecture can indeed provide guaranteed performance in a congested network, and that SBoX routers can be combined with commodity best-eort routers to enable QoS in a heterogeneous network.

This article deals with the integration of multicasting in Differentiated Services (DiffServ) networks. We shortly introduce the main problems and the research activities in this area, in order to define the problem and give a clear picture of the current state-of-the-art. Then, we propose a solution, which provides the multicast functionality and conforms to the DiffServ architectureÕs basic principles. The main idea is to extend the typical DiffServ components to support multicast operations. We also present an algorithm for the calculation of the minimum-cost tree, which connects the source with the destinations, taking into account the available bandwidth per service class. Important implementation issues are analyzed and it is shown how the whole architecture can be deployed. Moreover, we evaluate the proposed mechanism, using a number of experiments and simulation tests. Finally, we compare our framework with other QoS provisioning schemes.

At the extremes of the complexity-performance plane, there are two exemplary QoS management architectures: Integrated Services (IntServ) and Differentiated Services (DiffServ). IntServ performs ideally but is not scalable. DiffServ is simple enough to be adopted in today's core networks, but without any performance guarantee. Many compromise solutions have been proposed. These schemes, called quasi-stateful IntServ or stateful DiffServ, however, have not attracted much attention due to their inherently compromising natures. Two disruptive flow-based architectures have been recently introduced: the flowaware network (FAN) and the flow-state-aware network (FSA). FAN's control is implicit without any signaling. FSA's control is even more sophisticated than that of IntServ. In this paper, we survey established QoS architectures, review disruptive architectures, discuss their rationales, and points out their disadvantages. A new QoS management architecture, flow-aggregate-based services (FAbS), is then proposed. The FAbS architecture has two novel building blocks: inter-domain flow aggregation and endpoint implicit admission control.

Assuring end-to-end quality-of-service (QoS) in distributed real-time and embedded (DRE) systems is hard due to the heterogeneity and scale of communication networks, transient behavior, and the lack of mechanisms that holistically schedule different resources end-to-end. This paper makes two contributions to research focusing on overcoming these problems in the context of wide area network (WAN)-based DRE applications that use the OMG Data Distribution Service (DDS) QoS-enabled publish/subscribe middleware. First, it provides an analytical approach to bound the delays incurred along the critical path in a typical DDS-based publish/subscribe stream, which helps ensure predictable end-to-end delays. Second, it presents the design and evaluation of a policy-driven framework called Velox. Velox combines multi-layer, standards-based technologies-including the OMG DDS and IP DiffServ-to support end-to-end QoS in heterogeneous networks and shield applications from the details of network QoS mechanisms by specifying per-flow QoS requirements. The results of empirical tests conducted using Velox show how combining DDS with DiffServ enhances the schedulability and predictability of DRE applications, improves data delivery over heterogeneous IP networks, and provides network-level differentiated performance.

As the Internet evolves into global communication and commercial infrastructure, the need for quality-of-services (QoSs) in the Internet becomes more and more important. With a bandwidth broker (BB) support in each administrative domain, differentiated services (Diffserv) is seen as a key technology for achieving QoS guarantees in a scalable, efficient, and deployable manner in the Internet. In this paper, we present a scalable model for inter-BB resource reservation and provisioning. Our BB uses centralized network state maintenance and pipe-based intradomain resource management schemes that significantly reduce admission control time and minimize scalability problems present in prior research. For inter-BB communication, we design and implement a BB resource reservation and provisioning protocol (BBRP). BBRP performs destination-based aggregated resource reservation based on bilateral service level agreements (SLAs) between peer-BBs. BBRP significantly reduces the BB and border routers state scalability problem by maintaining reservation state based only on destination region. It minimizes inter-BB signaling scalability by using aggregated type resource reservation and provisioning. Both analytical and experimental results verify the BBRP achievements.

Assuring end-to-end QoS in enterprise distributed real-time and embedded (DRE) systems is hard due to the heterogeneity and transient behavior of communication networks, the lack of integrated mechanisms that schedule communication and computing resources holistically, and the scalability limits of IP multicast in wide-area networks (WANs). This paper makes three contributions to research on overcoming these problems in the context of enterprise DRE systems that use the OMG Data Distribution Service (DDS) quality-ofservice (QoS)-enabled publish/subscribe (pub/sub) middleware over WANs. First, it codifies the limitations of conventional DDS implementations deployed over WANs. Second, it describes a middleware component called Proxy DDS that bridges multiple, isolated DDS domains deployed over WANs. Third, it describes the NetQSIP framework that combines multi-layer, standards-based technologies including the OMG-DDS, Session Initiation Protocol (SIP), and IP DiffServ to support end-to-end QoS in a WAN and shield pub/sub applications from tedious and error-prone details of network QoS mechanisms. The results of experiments using Proxy DDS and NetQSIP show how combining DDS with SIP in DiffServ networks significantly improves dynamic resource reservation in WANs and provides effective end-to-end QoS management.

Este artigo defende a adequação modelo relativo proporcional no contexto da implementação de QoS em servidores web, e propõe o uso do conceito de valor cumulativo como métrica adotada na diferenciação de serviços. Objetivando manter a diferenciação de serviços, esse artigo apresenta uma abordagem de escalonamento adaptativo que atua através da heurística Proportional Cumulative Value Attribution (PCV). Essa heurística age através de duas políticas que, simultaneamente, ordenam as requisições conforme prioridades atribuídas dinamicamente; e selecionam diferentes versões de páginas web para responder as requisições.

Providing quality of service (QoS) is one of the main challenges in the internet that has recently gained the interest of many researchers. The internet architecture was originally designed to provide IP based ''best effort" services to all its applications. The best effort service could be acceptable for traditional applications such as email and web browsing, however, it is inadequate for new classes of emerging applications with real time data such as audio and video streaming. These new applications demand good quality of service from the network due to their inherent high data throughput (bandwidth) and low-latency requirements. Three main architectures were proposed by IETF in an effort to make the IP QoS a reality. They are integrated services (Intserv), differentiated services (DiffServ) and multiprotocol label switching (MPLS). Sometimes perceived as competitor, DiffServ and MPLS are in fact complementary developments that approach the QoS challenge from two different network perspectives. Thus these two approaches can be used together in order to combine their merits. This paper discusses an improved admission control which is aimed at enabling MPLS-TE tunnels differentiations (DS-TE tunnels). It presents a simulation based study which demonstrates the effectiveness of the proposed scheme where DiffServ EF traffic is mapped to MPLS tunnel to ensure stable performance for the traffic in the MPLS Domain.

Differentiated Service (DiffServ) architecture has been proposed as a scalable QoS architecture for Internet. DiffServ, however, could not control its loads under heavy traffic conditions, and it could not provide strong QoS responses for individual traffic flow. This paper introduces at the edges of a DiffServ domain, a novel two-level admission control scheme, the Fair Intelligent Admission Control (FIAC). At per-class level, FIAC admits traffic according their fairshare and usage while preventing possible congestion within the DiffServ core. At perflow level, FIAC estimates and allocates the fairshare for each flow within a class. Simulation results demonstrate that FIAC adheres extremely well to the bandwidth requirements of DiffServ classes while preventing congestion within the DiffServ core. With FIAC's per-flow level enabled, FIAC is able to prevent uncontrolled UDP flows from depriving TCP-controlled flows of bandwidth share when they are aggregated to the DiffServ domain.

Broadband satellite systems will need specific functions and interfaces in order to fit seamlessly into an endto-end Next Generation Network (NGN) Quality of Service (QoS) architecture. This paper will define NGN overall architecture, showing how the coupling between Application/session layers and Network/transport layers can achieve end-to-end QoS support. Possible integration scenarios of satellite access into such architectures will be depicted, with a special emphasis on transparent and regenerative satellite architectures based on DVB-RCS [14] type of access.

The paper discusses a DVB/IP backhaul networking environment that enables users to access triple-play IP services at a guaranteed end-to-end QoS level. Utilising the DVB-T stream in a regenerative configuration, it presents the formation of a QoS aware backhaul that interconnects intermediate distribution nodes and service/content providers (e.g. ISPs, IPTV multicasters, etc.), for enabling always-on and triple-play services access, even from rural or dispersed areas. The capability of the proposed QoS aware DVB/IP backhaul networking environment is validated through experimental tests, that were conducted under real transmission/reception conditions at a prototype infrastructure that conforms to the discussed architectural design issues.

The paper discusses the end-to-end QoS provisioning for scalable video streaming traffic delivery over heterogeneous IP/UMTS networks. A prototype architecture is proposed, and is further validated, that explores the joint use of packet prioritization and scalable video coding (SVC) together with the appropriate mapping of UMTS traffic classes to the DiffServ traffic classes. A complete set of simulation scenarios, involving eight different video sequences and using two different scalable encoders, demonstrates the quality gains of both scalable video coding and prioritized packetization.

This paper presents integrated mechanisms for differentiated service (DiffServ) architecture consisting of active rate management (ARM) at the edges of the network and two color Active Queue Management (AQM) controllers at the core of the network. AQM controller is a robust linear quadratic regulator based Proportional-Integral-Derivative controller for two colors marking at the core. The proposed mechanism is for DiffServ assured forwarding per hop behavior for guaranteeing minimum rates for exact and over provisioned systems. The performance of proposed scheme is evaluated and compared with other approaches by using the NS-2 simulator.

Assuring end-to-end quality-of-service (QoS) in distributed real-time and embedded (DRE) systems is hard due to the heterogeneity and scale of communication networks, transient behavior, and the lack of mechanisms that holistically schedule different resources end-to-end. This paper makes two contributions to research focusing on overcoming these problems in the context of wide area network (WAN)-based DRE applications that use the OMG Data Distribution Service (DDS) QoS-enabled publish/subscribe middleware. First, it provides an analytical approach to bound the delays incurred along the critical path in a typical DDS-based publish/subscribe stream, which helps ensure predictable end-to-end delays. Second, it presents the design and evaluation of a policy-driven framework called Velox. Velox combines multi-layer, standards-based technologies-including the OMG DDS and IP DiffServ-to support end-to-end QoS in heterogeneous networks and shield applications from the details of network QoS mechanisms by specifying per-flow QoS requirements. The results of empirical tests conducted using Velox show how combining DDS with DiffServ enhances the schedulability and predictability of DRE applications, improves data delivery over heterogeneous IP networks, and provides network-level differentiated performance.

With the fast adoption of IP-based communications for mobile computing, users are expecting a similar service in wireless and wired networks. This raises the need for setting guarantees to the quality of the offered service (QoS), despite the technology of the access network (AN) or the mobility of the terminal. As mobile computing is getting more popular on a daily basis, new broadband cellular wireless ANs will appear with overlapping coverage in hot spots. This generates a new challenge for QoS provision, as it will have to deal with fast mobility of terminals. Various QoS architectures have been defined, but none provides full support for guaranteed service levels for mobile hosts (MHs). This paper discusses the problems related to providing QoS to MHs and identifies the existing solutions and future work needed. Ó

The demand for QoS provisioning support over Internet grows continuously. The most scalable and less demanding solution, in terms of necessary modifications to the existing Internet infrastructure, is the Differentiated Services (DiffServ) architecture. In this approach, little care has been taken for on a per-application or a per-user basis QoS provisioning. Nevertheless, the Service Level Agreements (SLAs) need to be selected in a way that is efficient both for the users and for the network. In this paper, we develop and evaluate an approach for efficient SLA selection and employing in a DiffServ-over-MPLS network domain. A negotiation process between a user and a network provider is introduced; thus the user can choose from alternative options for allocation of resources the one that better matches his needs. We adopt a usage-based charging scheme that provides the user with the right incentives for SLA selection.© (2001) COPYRIGHT SPIE--The International Society for Optical Engi...

Recently, a class of solutions including Core-Stateless Fair Queueing (CSFQ), Rainbow Fair Queueing, and Diffserv have been proposed to address the scalability concerns that have plagued stateful architectures such as Intserv and Fair Queueing. However, despite some desirable properties, these solutions still have serious scalability, robustness, and deployment problems. Their scalability, suffers from the fact that the core cannot transcend trust boundaries (such as at ISP-ISP interconnects), and so the high-speed routers on these boundaries must maintain per flow or per aggregate state. The lack of robustness is because a single malfunctioning edge or core router could severely impact the performance of the entire network. The deployability is hampered because the set of routers must be carefully configured with a well-defined set of edge routers surrounding the core. In this paper, we propose an approach to address these limitations. The main idea is to use statistical verification to identify and contain the flows whose packets carry incorrect information. To demonstrate the applicability of this approach we develop an extension of CSFQ, called Self-Verifying CSFQ (SV-CSFQ). With SV-CSFQ, rate estimation is performed by sending hosts, and all routers statistically verify these rate estimates. Statistical verification allows routers to identify misbehaving flows and routers, and thereby protect other flows. This makes our approach robust and highly scalable as it eliminates the need for stateful routers at trust boundaries, and for the core-edge distinction. We present simulations and analysis of the performance of this approach, and discuss its general applicability to provide other scalable and robust network services.

As the Internet evolves, and new bandwidth-consuming multimedia applications become more common, it becomes necessary to provide quality of service (QoS) in the Internet. QoS provides a basis for network providers to offer a variety of services to customers with different cost, bandwidth, latency, and jitter requirements, which makes the network resources more valuable. To utilize valuable network resources efficiently, service providers need to engineer intra-domain and inter-domain traffic. In this dissertation we are addressing the inter-domain traffic engineering problem with emphasis on inter-domain QoS routing, which is the most important component of traffic engineering. This dissertation introduces a novel inter-domain QoS routing scheme that can scale over large networks. Our scheme is based on the notion of regions, which are collections of autonomous systems, and we represent the overall Internet topology as a collection of regions. Without introducing a hierarchy, we emp...

Keywords:Inter-Domain Traffic Engineering, Inter-Domain QoS Routing Protocol, Bandwidth Brokers, Diffserv Abstract In this paper, we are proposing an Inter-domain traf-fic engineering architecture over a Bandwidth Broker (BB) supported Diffserv internet. The main ...

A critical issue for the convergence of telephone networks towards an all IP environment is the provisioning of an adequate QoS level to the telephone traffic. Following the guidelines detailed in RFC 2990, we recently proposed an admission control function, named Gauge & Gate Reservation with Independent Probing (GRIP), through which we are able to provide QoS guarantees by means of stateless procedures compliant within the Differentiated Service (DiffServ) paradigm, which is the de facto standard for QoS provisioning in Internet. The main goal of this paper is to present a specific implementation of GRIP optimized for supporting voice over IP (VoIP) services within a DiffServ cloud. In particular, we propose and analyze a simple measurement-based call admission control procedure for carrying VoIP traffic in a DiffServ environment. We assume voice sources are leaky bucket controlled with known leaky bucket parameters. We analyze the leaky bucket to derive the distribution of the times over which voice sources generate traffic at peak and regulated rates. We use the results of that analysis, which provides complete knowledge of the traffic generation characteristics of a single source, to derive a Markov chain model that characterizes the voice packet generation process of a single voice source. We then derive a simple stateless threshold policy for admission control; that is, our policy is of the form if, at admission request time, x 6 x threshold , admit the call; else reject the call. Finally, we show, via simulation, that the QoS achieved using the threshold-based admission control policy is very close to that achieved by a stateful admission control policy even at very high traffic utilization.

The main objective of the IETF Differentiated Services (DiffServ) model is to allow the support on the Internet of different levels of service to different sessions and information flows, aggregated in a few number of traffic classes. This model shows some security limitations that are inherent to the DiffServ model. This paper proposes an architecture for Authentication, Authorization, Admission control and Accounting (AAAA) of QoS client applications with dynamic identification of sessions and flows, based on the PBN paradigm. The proposal functionalities are described and analyzed in some detail, focusing on a set of extensions to the Common Information Model of the DMTF. The paper ends with the discussion of the main advantages of the proposal over existing solutions.

In a multi-service network, different applications have varying QoS requirements. The IETF has proposed the DiffServ architecture as a scalable solution to provide Quality of Service (QoS) in IP Networks. In order to provide quantitative guarantees and optimization of transmission resources, DiffServ mechanisms should be complemented with efficient traffic engineering (TE) mechanisms, which operate on an aggregate basis across all classes of service. The MultiProtocol Label Switching (MPLS) technology is a suitable method to provide TE, independent of the underlying layer2 technology. Currently, the combined use of Differentiated Services (DiffServ) and MPLS is a promising technique to provide Quality of Service (QoS), while efficiently exploiting network resources. In this paper, TEAM, an automated manager for DiffServ/MPLS networks,is introduced and its design. The design and implementation,details are discussed. q 2002 Elsevier Science B.V. All rights reserved. Keywords: DiffServ...

Combining Integrated Services ([1], [5]) QoS mechanisms for end-to-end signaling at hosts and Differentiated Services ([2], [10]) QoS mechanisms in the network core is one proposal for overcoming the limitation of either mechanisms when applied alone ([8]). In this paper some of the open issues in [8] are discussed and a concrete proposal is presented, which maps the IntServ Controlled Load Service into the DiffServ Expedited Forwarding "Per Hop Behavior". The proposed approach has been implemented under the Linux Operating System. The implementation allows verifying the correct functional behavior and provides a platform where more complete performance tests are possible.

This paper introduces a new packet marking algorithm that can be used in the context of Assured Forwarding (AF) in the Differentiated Services (DiffServ) framework [1], [2]. The new marking algorithm is called Equation-Based Marking (EBM) and is based on the TCP model in [3]. EBM is to handle the problems found in other marking schemes regarding fairness among heterogeneous TCP flows through a tight feedback-loop operation and adaptation of the packet marking probability to network conditions. We design a packet marker that uses EBM as the marking algorithm, and evaluate its performance using in-depth simulation. We also prove analytically the correctness of the marking algorithm and compare it with other marking schemes for different network scenarios. Our evaluation results demonstrate the effectiveness of EBM in providing the required fairness among heterogeneous flows and ensuring protection against non-assured traffic.

The protection of service delivery in an integrated network is fast becoming a critical issue. In previous work, we proposed two protection methods, DiffServ and DiffProtect and examined, on a small network, whether DiffServ can be used as a protection mechanism against failures in IP/WDM networks. The results showed that, on average, DiffServ can provide better QoS guarantees than its optical counterpart, DiffProtect. We also found that DiffProtect may perform better than DiffServ under some extreme failure situations so that DiffServ cannot totally replace optical protection in a network but might be able to do so to some degree. We extend these results to larger networks and more complex combinations of protection techniques. We study in this paper a 4-node linear topology and a small 6node mesh network which can be protected by DiffServ, DiffProtect or even a combination of both (MixProtect). Results show that replacing optical protection by DiffServ cannot be done randomly and that the number and position of links protected by DiffServ versus Diff-Protect must be carefully chosen in order to guarantee adequate performance to all traffic types. We explain how this can be achieved with current technology. We also show that the cost of protection using DiffServ is significantly less than that of current methods.

The basic DiffServ model lacks mechanisms to prevent itself from being overloaded and to inform its internal capability to the external world. This paper addresses the problem by presenting a Fair Intelligent Admission Control (FIAC) over an enhanced-DiffServ architecture. The central idea is to make admission decision based on both informed internal network QoS states and the external traffic QoS requirements at the edge node. This model has several advantages: (1) it is backward compatible with DiffServ, (2) it adapts to traffic load and network QoS state changes, and (3) it provides interactive communication between the external QoS requirements and the internal DiffServ network capability. In this paper, we use simulation to evaluate the performance of DiffServ with or without FIAC. The performance demonstrates that the new scheme is able to admit traffic fairly and achieve edge-to-edge QoS under heavy traffic conditions and network state changes.

In networks based on the Differentiated Services (DiffServ) architecture, users may be presented the opportunity to choose their Assured Forwarding (AF) class. Users will attempt to maximize their Consumer Surplus (CS) in such an environment. They can increase their CS by choosing the lowest cost AF class that satisfies their Quality of Service (QoS) requirements. Previously the authors have proposed an algorithm known as Consumer Surplus Maximization (CSM) [2]. Although this algorithm improves CS for users, widespread adoption of the algorithm can provoke network instability. If many users switch classes at once, degradation on one AF class can easily propagate. The likelihood of such an occurrence can be reduced by replacing fixed perbyte or per-packet charges associated with individual AF classes with a lightweight Congestion-only Charging (CoC) pricing mechanism. An additional charge is only applied to packets that receive discernible benefit from belonging to a particular class. We present simulation results from a networking scenario where users connect across a single DiffServ domain to engage in a multiplayer First Person Shooter (FPS) game.

This paper presents integrated mechanisms for differentiated service (DiffServ) architecture consisting of active rate management (ARM) at the edges of the network and two color Active Queue Management (AQM) controllers at the core of the network. AQM controller is a robust linear quadratic regulator based Proportional-Integral-Derivative controller for two colors marking at the core. The proposed mechanism is for DiffServ assured forwarding per hop behavior for guaranteeing minimum rates for exact and over provisioned systems. The performance of proposed scheme is evaluated and compared with other approaches by using the NS-2 simulator.

This letter considers problems of unfairness and excessive variations of the router queue associated with FAST TCP operations due to inaccurate estimation of the round-trip propagation delay. Using a simple example, we explain unfairness in FAST TCP caused by this inaccurate estimation. We also present analytical and simulation performance studies and show that improving this estimation by giving the first packet in every flow priority can improve fairness and reduce queuing variations.