Provide Service Differentiation Research Articles

Capacity-aware state aggregation for interdomain QoS routing

Quality-of-service (QoS) routing between domains is an essential component for providing service differentiation in the Internet. State aggregation is a technique that makes QoS routing scalable to large internetworks, by presenting a concise and accurate representation of the domain to the routing process. The concept of using a domain's routing capacity as a bandwidth aggregate has been in existence for some time. However, no methodology has been suggested in the literature for its estimation and usage. Also, the impact of a domain's routing capacity on the routing performance has not been studied before. This paper aims to fill these voids by presenting a framework based on flows for estimating a domain's routing capacity and evaluating its efficacy on the routing performance. The routing capacity is used in conjunction with the conventional widest path bandwidth as the domain aggregate. Analytical and experimental results show that appropriate use of routing capacity along with the widest path bandwidth reduces the tendency of the advertised aggregate to overestimate bandwidth availability, and makes the routing process more robust to the frequency of domain state updates. During periods of congestion, the use of routing capacity can improve the bandwidth admitted into the network by as much as 20%

MANETs에서 차등서비스 제공을 위한 트래픽 관리 기법

인터넷에서 차등서비스에 관한 연구는 IETF 그룹에서 표준화되었으나, Ad-hoc 네트워크와 같은 무선 환경에서 인터넷의 차등 서비스는 MAC과 같은 하위레벨 지원 없이는 구현하기가 어렵다. 현재 IEEE 802.11 프로토콜은 무선 랜 환경에 광범위하게 쓰이며 사실상의 표준으로 자리 잡았다. 그러나 차등서비스 제공을 위한 모드를 지원하지만, 성능이 낮은 것으로 나타났다. 본 논문에서는 802.11 에서 QoS 제공을 위해 우선순위를 지원하는 다중 큐 기반의 새로운 알고리즘을 제안하고 시뮬레이션을 통해 IEEE 802.11의 큐영시스템과 성능을 비교, 분석하였다. 컴퓨터 시뮬레이션 결과 제안한 알고리즘 방식의 성능이 우수했음을 보였다. Currently, the IETF group is working on service differentiation in the Internet. However, in wireless environments such as Ad-hoc networks, where channel conditions are variable and bandwidth is scarce, the Internet differentiated services are suboptimal without lower layers' support. The IEEE 802.11 standard for Wireless LANs is the most widely used WLAN standard today. 1t has a mode of operation that can be used to provide service differentiation, but it has been shown to perform badly. In this paper, we present a new service differentiation scheme for support QoS in the wireless IEEE 802.11, which is based on a multiple queuing system to provide priority of user's flow. We simulate and analyze the performance of our algorithm and compare its performance with the original IEEE 802.11b protocol. Simulation results show that our approach increases overall throughput in the MAC layer.

Bringing IPTV to the Market through Differentiated Service Provisioning

<p>The world of telecommunications continues to provide radical technologies. Offering the benefits of a superior television experience at reduced long-term costs, IPTV is the newest offering. Deployments, however, are slow to be rolled out; the hardware and software support necessary is not uniformly available.<br /> This paper examines the challenges in providing IPTV services and the limitations in developments to overcome these challenges. Subsequently, a proposal is made which attempts to help solve the challenge of fulfilling real-time multimedia transmissions through provisioning for differentiated services. Initial implementations in Opnet are documented, and the paper concludes with an outline of future work.</p>

Burst-cluster transmission: service differentiation mechanism for immediate reservation in optical burst switching networks

In this article we propose a service differentiated burst transmission called burst-cluster transmission to provide service differentiation in terms of burst loss for optical burst switching networks. The proposed method consists of a burst assembly algorithm and burst transmission scheduling, and it works only at the ingress edge node. A mixed timer/burst-length-based assembly algorithm is considered for burst assembly, and bursts with different service classes are assembled simultaneously according to the algorithm. A burst-cluster is generated so that the bursts in the cluster are arranged in order from lowest priority to highest. Then the burst-cluster is transmitted according to the burst transmission scheduling. We also consider the application of burst-cluster transmission to delay-sensitive traffic. We evaluate by simulation the performance of the burst-cluster transmission for NSFNET. Numerical examples show that burst-cluster transmission succeeds in providing different service grades even though the burst loss probabilities of high-priority service classes are affected by the traffic load of low-priority ones

Call admission and code allocation strategies for WCDMA systems with multirate traffic

In this paper, call admission and code allocation schemes are proposed to provide service differentiation in the forward link of wideband code-division multiple-access (WCDMA) systems. In particular, this paper proposes multiple leaf code reservation (MLCR) schemes, where different numbers of orthogonal variable spreading factor (OVSF) leaf codes (i.e., codes of the lowest layer of the OVSF code tree) are reserved to differentiate users with different bandwidth requirements. Leaf codes are only reserved for as long as the call admission process lasts. Once the decision of whether a new request is admitted or not has been made, a Code Dereservation procedure is carried out to increase flexibility in the code assignment phase. The performance of these MLCR strategies with/without code reassignments is then evaluated. Analysis shows that MLCR schemes are also useful in improving fair access among different traffic classes. In addition, perfect fair access among requests with different data rates can be achieved when code reassignments are jointly employed with the proposed OVSF-code reservation schemes.

Multiservice provisioning mechanism with service curves assurance for per-class scheduling delay guarantees

Class-based traffic treatment frameworks, such as differentiated service (DiffServ), have been proposed to solve the scalability problem of flow-based approach for quality of service (QoS) provisioning. While these frameworks provide service differentiation according to traffic classes, the provision of QoS guarantee for individual flows, within a class, remains a challenging problem. In the paper, the authors present a novel multiservices mechanism, which is able to provide service curves assurance for per-flow deterministic delay guarantees. The core component of this mechanism is a new packet scheduling algorithm, called flow-state-dependent packet scheduling (FDPS), to handle different flows within the same class to provide end-to-end scheduling delay bound guarantees. The mechanism is based on an analysis that guides the flow admission control operation for class-based queueing delay bound. Using the packets' flow-states, FDPS provides fine granularity packet service differentiation within each class. By means of this property, the proposed mechanism achieves per-flow end-to-end delay bound independent of the number of intermediate nodes along the path of the flow. Another notable feature is that it can be integrated into a DiffServ framework as an enhancement for deterministic QoS guarantees. The performance of this mechanism is mathematically analysed to demonstrate its enhancements and ns-2 simulation experiments are used to validate the analytical results.

A Load-Balancing and Push-Out Scheme for Supporting QoS in MANETs

Currently, mobile ad hoc networks (MANETs) lack load-balancing capabilities, and thus, they fail to provide good performance especially in the case of a large volume of traffic. Ad hoc networks lack also service differentiation. However, in these wireless environments, where channel conditions are variable and bandwidth is scarce, the differentiated services developed for the Internet are suboptimal without lower layers' support. The IEEE 802.11 standard for Wireless LANs is the most widely used WLAN standard today. It has a mode of operation that can be used to provide service differentiation, but it has been shown to perform badly.In this paper, we present a simple but very effective method for support Quality of Service, by the use of load-balancing and push-out scheme. This approach offers to the mobile node: the ability to alleviate congestion by traffic distribution of excessive load, and to support priority of packets in the single MAC buffer. We evaluate the performance of our algorithm and compare it with the original IEEE 802.11b protocol. Simulation results show that this new approach reduces packet loss rate and increases throughput as well as provides service differentiation in the MAC layer.

A real-time video multicast architecture for assured forwarding services

This paper presents our work on developing an architecture for multicasting real-time MPEG4 over IP networks that provide service differentiation. In particular, this work is targeted at assured forwarding (AF) style services. This work is an attempt to find a simple solution to the problem of multicast congestion control of real-time traffic by exploiting the service differentiation capabilities of AF networks. Our architecture assumes loss differentiation in the network and assumes the network's ability to provide explicit congestion notification messages to the sender. We do not consider policing/shaping at the edge routers. Rather, we consider a more general case where packet marking and flow control are provided at the senders. For this network model, we built an end-to-end architecture and developed a rate-adaptation algorithm that can operate in both unicast and multicast applications with a minor modification. The simulation results show how the rate-adaptation algorithm accommodates different receivers with different networking capabilities and provides receivers with different levels of quality by taking advantage of the queue management capabilities of the AF service. We test how the architecture scales to a large number of receivers, how multiple multicast sessions interact, and how it interacts with TCP.

Performance evaluation for IEEE 802.11e enhanced distributed coordination function

AbstractThe IEEE 802.11e working group aims to enhance the current 802.11 medium access control (MAC) to support integrated data and voice (or video) communications. Till now, a draft of the IEEE 802.11e enhanced distributed coordination function (EDCF) has been proposed. In the literature, there is very limited analysis about EDCF since it is a new protocol, and most related work are only confined to simulation or saturation state. In this paper, we evaluate the performance of EDCF by dividing the traffic into two groups, namely real‐time packets and non‐real‐time packets, and use an analytical model to quantify the performance of both IFS priority and contention window (CW) priority in the EDCF. In our analysis, we assume that the traffic arrival is a Poisson process. We provide a queue model for EDCF. Since there are multiple stations contending for one channel in the system, the queue model for EDCF cannot be a regular M/G/1 model. We redefine the service time and the waiting time so that we can still use M/G/1 model in the analysis. To validate the accuracy of our analytical results, we have done extensive simulations and we observed that EDCF does provide service differentiation between different traffic categories. But due to the inherent contention characteristic of carrier sense multiple access with collision avoidance (CSMA/CA) MAC protocol, the delay cannot be guaranteed, even for the highest priority traffic. A lot more work needs to be done for the MAC protocol to effectively support service differentiation in the future. Copyright © 2004 John Wiley & Sons, Ltd.

Polymorphic Architectures for Optical Networks and their Seamless Evolution towards Next Generation Networks

This paper proposes a novel polymorphic framework for optical networking and a seamless evolution path from optical circuit-switched towards optical packet-switched networks. We show that by simultaneously supporting several optical switching paradigms in a single physical topology, efficient and flexible optical networks can be built. The supported paradigms are associated with different Classes of Service (CoS) in order to provide service differentiation at the optical layer. Two polymorphic architectures are presented, one based on optical circuit switching paradigms with different grades of dynamism, and a second one based on optical labeled burst-switched networks with the added capability of dynamic lightpath provisioning. These architectures provide a seamless evolution path towards an efficient IP-over-WDM approach with service differentiation. Moreover, the proposed polymorphic architectures are fully compatible with the GMPLS unified control plane. We present in a detailed form the proposed polymorphic framework, including the selection of switching paradigms, its support for CoS, the network and control architecture, and a possible seamless evolution towards optical packet-switched networks. Possible implementation examples of optical network nodes that support the proposed polymorphic architectures are also presented.

Out‐of‐band polling scheme for QoS support in wireless LANs

AbstractRecent researches in wireless local area networks (WLANs) have shown the challenges in providing an effective scheme to realize high throughput and transmission of real‐time traffic with a certain quality of service. This scheme must facilitate low worst‐case delay bounds and scale with the increase of data rate as technology advances. We introduce out‐of‐band polling scheme (OBPS), which separates the signalling for packet transmissions from the data channel; it uses an efficient polling method on a signalling channel for an access point to schedule packet transmissions with different priorities for upstream transmission. We also include a transmission sequences to efficiently schedule delivery of real‐time downstream packets. OBPS can adopt any packet scheduling algorithms to provide service differentiation. We choose deficit round robin scheduling algorithm for upstream and downstream traffic to provide rate differentiation and fairness. Through analytical and simulation results, we show that OBPS can achieve high throughput, provide rate differentiation and support bidirectional transmissions of real‐time packets. We derive upstream and downstream worst‐case delay bounds for OBPS, which serve as parameters for analysing scheduling algorithms that can be deployed to achieve a certain quality of service for real‐time packets. To illustrate that, we derive the worst‐case delay bounds of OBPS with DRR. Our delay bounds are realistic as it is based on upstream and downstream packet transmissions on a half‐duplex channel. We also show that OBPS is scalable for deployment in future high speed WLANs. Copyright © 2004 John Wiley & Sons, Ltd.

A survey of QoS enhancements for IEEE 802.11 wireless LAN

Quality-of-service (QoS) is a key problem of today's IP networks. Many frameworks (IntServ, DiffServ, MPLS etc.) have been proposed to provide service differentiation in the Internet. At the same t...

A survey of QoS enhancements for IEEE 802.11 wireless LAN

AbstractQuality‐of‐service (QoS) is a key problem of today's IP networks. Many frameworks (IntServ, DiffServ, MPLS etc.) have been proposed to provide service differentiation in the Internet. At the same time, the Internet is becoming more and more heterogeneous due to the recent explosion of wireless networks. In wireless environments, bandwidth is scarce and channel conditions are time‐varying and sometimes highly lossy. Many previous research works show that what works well in a wired network cannot be directly applied in the wireless environment. Although IEEE 802.11 wireless LAN (WLAN) is the most widely used IEEE 802.11 wireless LAN (WLAN) standard today, it cannot provide QoS support for the increasing number of multimedia applications. Thus, a large number of 802.11 QoS enhancement schemes have been proposed, each one focusing on a particular mode. This paper summarizes all these schemes and presents a survey of current research activities. First, we analyze the QoS limitations of IEEE 802.11 wireless MAC layers. Then, different QoS enhancement techniques proposed for 802.11 WLAN are described and classified along with their advantages/drawbacks. Finally, the upcoming IEEE 802.11e QoS enhancement standard is introduced and studied in detail. Copyright © 2004 John Wiley & Sons, Ltd.

Review of quality of service performance in wireless LANs and 3G multimedia application services

Although, many architectures (Integrated Services, Differentiated Services, MPLS, Traffic Engineering, etc.) have been proposed to provide service differentiation in fixed networks, research has shown that what works well in a wired network cannot be directly applied in the wireless environment where bandwidth is scarce and channel conditions are time varying. Quality of Service (QoS) is a key challenge for today's wireless IP networks and implementation of QoS, particularly for supporting voice, video, data and multimedia services in general incurs a number of difficulties that have to be analysed and resolved. A considerable amount of work has been carried out by the various standards groups in an effort to quantify and specify protocols to support QoS in wireless environments. This paper reports on these efforts outlining existing limitations, requirements and solutions proposed by organisations such as the IEEE 802.11 Task Group E for wireless LANs and the UMTS effort for 3G/wireless WANs.

Providing Service Differentiation for Optical-Burst-Switched Networks

This paper proposes a service differentiation scheme called preemptive wavelength reservation protocol (PWRP) to provide proportional quality of service (QoS) for optical-burst-switched (OBS) networks. In the context of service differentiation, traffic is divided into different service classes based on traffic characteristics. A service differentiation scheme then provides different degrees of resource assurance to different classes of traffic in proportion to their service classes. Unlike existing approaches, which may degrade to classless schemes or which may suffer from low wavelength utilization, the mechanism in this paper is robust and efficient and supports an incremental deployment of QoS support. A usage profile for each class is maintained at the router, and a preemptive wavelength reservation mechanism is implemented to ensure QoS. An analytical model is derived and simulations are conducted to evaluate the performance. The results show that the approach described in this paper performs better than existing mechanisms in terms of lower blocking probability and higher resource utilization, making it an excellent QoS mechanism for OBS networks.

A game theoretic approach to provide incentive and service differentiation in P2P networks

Traditional peer-to-peer (P2P) networks do not provide service differentiation and incentive for users. Consequently, users can obtain services without themselves contributing any information or service to a P2P community. This leads to the "free-riding" and "tragedy of the commons" problems, in which the majority of information requests are directed towards a small number of P2P nodes willing to share their resources. The objective of this work is to enable service differentiation in a P2P network based on the amount of services each node has provided to its community, thereby encouraging all network nodes to share resources. We first introduce a resource distribution mechanism between all information sharing nodes. The mechanism is driven by a distributed algorithm which has linear time complexity and guarantees Pareto-optimal resource allocation. Besides giving incentive, the mechanism distributes resources in a way that increases the aggregate utility of the whole network. Second, we model the whole resource request and distribution process as a competition game between the competing nodes. We show that this game has a Nash equilibrium and is collusion-proof. To realize the game, we propose a protocol in which all competing nodes interact with the information providing node to reach Nash equilibrium in a dynamic and efficient manner. Experimental results are reported to illustrate that the protocol achieves its service differentiation objective and can induce productive information sharing by rational network nodes. Finally, we show that our protocol can properly adapt to different node arrival and departure events, and to different forms of network congestion.

An investigation of multilevel service provision for voice over IP under catastrophic congestion

QoS has been the dominating issue faced in VoIP development today. In this article we investigate and empirically evaluate three DiffServ (Kilkki 1999, Blake et al. 1998) design strategies, WRED Dropper (Cisco Systems), PQ meter, and multiple differentiated meter (MDM), and study how multilevel communication services can be guaranteed for multiple VoIP classes. The novel aspect of our work is that we are trying to provide solutions with the use of features that are not currently available in real routers (Westhead, 2002). By taking advantage of network simulation techniques, a series of experiments have been designed and carried out under different network conditions by using the intersim simulation tool (Westhead, 2002). Our simulation results effectively reflect that: 1) all three designs can provide service differentiation for multiple VoIP classes; 2) the highest-priority VoIP class can always be protected under catastrophic congestion; and 3) each design has some pros and cons in terms of performance stability under varied traffic distribution and changed packet size mix. Based on this investigation, we conclude that MDM is comparatively better at providing even service distribution and staying robust against traffic distribution variation and packet size changes.

Differentiated QoS for survivable WDM optical networks

Optical networks based on WDM technology have become a promising solution to realize transport networks that can meet the ever-increasing demand for bandwidth. As WDM networks carry a huge volume of traffic, maintaining a high level of survivability is an important and critical issue. The. development of GMPLS switching technology led to the direct integration of IP and WDM. In these IP-over-WDM networks different applications/end users need different levels of fault tolerance and differ in how much they are willing to pay for the service they get. The current trend in network development is moving toward a unified solution providing support for voice, data, and various multimedia services. Therefore, it imperative that WDM networks incorporate fault tolerance to single or multiple component failures, protection bandwidth, recovery time, and recovery granularity besides resource utilization and call acceptance ratio. This article presents a survey of various methods that have been proposed for providing service differentiation in survivable WDM networks and discuss their performance. Such methods are broadly classified under various paradigms such as differentiated reliability, R-connections, quality of protection, and quality of recovery.

Performance analysis and evaluation of IEEE 802.11e EDCF

AbstractRecently, the IEEE 802.11 working group has announced a new distributed access mechanism called Enhanced DCF (EDCF) to provide service differentiation among traffic classes defined as access category. With the increasing demand for supporting Quality of Service (QoS) in IEEE 802.11 wireless LANs, the EDCF is now attracting many researchers' attention due to its practical worth as a standard mechanism. In this paper, we focus on the analytical approach to evaluate the performance of the EDCF. An analytical model is presented to estimate the throughput of the EDCF in saturation (asymptotic) conditions by substantially revising and extending the analytical model developed by Bianchi for the performance analysis of the DCF. Extensive simulation studies based on the NS‐2 simulator have been carried out for the validation of the analysis, and they show that it estimates the throughput of the EDCF accurately. By utilizing the analytical model, we evaluate the performance of the EDCF. Specifically, we concentrate on discovering the characteristics of the EDCF parameters, such as CWmin, CWmax and AIFS, in the way that they influence on the performance of the EDCF. Copyright © 2004 John Wiley & Sons, Ltd.

Nature-Inspired Routing and Wavelength Assignment Algorithms for Optical Circuit-Switched Polymorphic Networks

Polymorphic optical networks simultaneously support several optical switching paradigms over a single physical network. In this way, they provide service differentiation at the optical layer by employing the most appropriate paradigm for each service. One type of such architecture is the optical circuit-switched polymorphic network (OCSPN), which combines optical circuit switching paradigms with different grades of dynamism. The performance of this network relies on the utilization of efficient routing and wavelength assignment (RWA) algorithms. In this article, we review the fundamentals of OCSPNs and present a set of efficient RWA algorithms based on ant colony optimization and genetic algorithms.