QoS policy verification for DiffServ networks

This paper proposes novel resource sharing schemes for differentiated services (DiffServ) networks, to achieve both high resource utilization and quality of service (QoS) guarantee. Service level agreements (SLAs) are negotiated at network boundaries and supported by path-oriented resource mapping within the network. The recently proposed SLA management scheme based on virtual partitioning (Bouillet et al., 2002) allows overloaded SLAs to exploit the spare capacity of underloaded SLAs for efficient resource utilization, however, at the the cost of possible SLA violation of the underloaders. In the bandwidth borrowing scheme proposed here, the dedicated bandwidth for underloaded SLAs is determined and adaptively adjusted at network boundaries according to the actual traffic load and QoS policies; the available spare capacity is then properly distributed to related links for lending to others. On the other hand, the traffic flows admitted with borrowed bandwidth are tagged and may be preempted later when the original bandwidth owner needs to claim back the resources. Through a detailed implementation design and extensive computer simulation results we show that, by bandwidth borrowing, both SLA compliance and high resource utilization can be achieved in various load conditions, with some side benefits such as call-level service differentiation, small admission overhead, and convenience for policy-based management. In addition, we propose a distributed bandwidth pushing scheme that can dynamically adjust the spare bandwidth distribution over the network. Combining bandwidth pushing with bandwidth borrowing, the resource utilization can be further improved.

More and more applications of grid have been achieved. How to support Quality of Service (QoS) to meet different users' demand has raised an outstanding challenge. Currently, several QoS policies of resource have been widely used in Grid. Thus, how to use them freely and efficiently is a serious problem. In this study, we illustrated three QoS policies of resources: best effort, real time, and competing, and explain their mechanisms. Following this, we proposed a new QoS policy, namely Free QoS policy, to help the user who is not very familiar with QoS polices. The first step is that we can get the matrix of QoS parameters of each resource from the Policy Pool in which all the information about QoS policies of resources in “virtual organizations” could be obtained. Second, we will calculate every resource's P adjugment value by a comparison algorithm. Finally, the QoS policy matching the maximum value of P adjugment value is the user's decision. After choosing a suitable resource with a clear QoS policy, the next question is how to achieve an optimum quality under the given policy, which is the problem of scheduling. Min_Min algorithm has been widely used as a higher efficiency and simple algorithm. However, it has a serious problem: load unbalance. In order to solve the problem, we propose a novel task scheduling algorithm, called the Heuristic task scheduling algorithm based on Min-Min and Max-Min (H-MM) in the best effort of the QoS policy, which is merged with the high efficiency of the traditional Min-Min scheduling algorithm and the load balance of the traditional Max-Min scheduling algorithm. Through plenty of experiments, we know that the performance of Max-Min is better than that of Min-Min in the condition that the values of ETC are not uniform, and the performance of Min-Min is a priority to Max-Min when there are many tasks in which the value of ETC are uniform. In this paper, we take the relative standard deviation value of ETC matrix's Min_Time as the criterion to judge whether the set of tasks is uniform or not. Finally, the scheduler selects the Max-Min or Min-Min to assign tasks. The experiments have shown that the H-MM algorithm overweighs traditional algorithms a lot in the makespan and the scalability of the scheduling algorithm.

A service level agreement (SLA) is part of a contract between a cloud service provider (CSP) and a cloud service user (CSU) which defines and describes different agreed properties of the service. The negotiation of the SLA between a CSU and a CSP is a pivotal process in the SLA life cycle. An SLA may include many negotiable quality of service (QoS) parameters with each QoS parameter having multiple acceptable values. Different combinations of acceptable values for all QoS parameters grow exponentially as number of QoS parameters and their selectable values increase. Manually negotiating for all of the QoS parameters considering their various options can be an erroneous and diligent task with lower utility. In this paper, a time efficient flip-flop negotiation strategy for the SLAs in cloud services is presented. The flip-flop negotiation strategy is based on a time dependent 3D utility function and on a dynamic concession strategy using the polynomial extrapolation of opponent's concession. This negotiation strategy is useful for time-critical cloud services as it operates with a motive of reaching an agreement at earlier time without compromising over the utility level of the agreement. Moreover, a multi-provider concurrent negotiation method is presented in this work using the flip-flop negotiation strategy. Multiple experiments are performed (using the implementation of flip-flop negotiation strategy) to test the presented work. The results of the experiments enforce the validity of the flip-flop negotiation strategy for such cloud services where time is an important factor during the SLA negotiation process.

A Service Level Agreement (SLA) is a legal contract between parties to ensure the Quality of Service (QoS). It specifies one or more service level objectives (SLO), to ensure that the QoS delivered has met customer expectations. However, It becomes hard to guarantee QoS levels and detect SLA violations. Therefore, we propose to use MDE (Model Driven Engineering) to express the SLA contract requirements. This latter, created with a specific modeling language (DSML), will be used harmonically with a Multi-agent systems (MASs) in order to monitor SLA violations in real-time. Indeed, MASs are suitable tools for self-detection of failures and self-monitoring of cloud operations and services, QoS negotiation and SLA management. They are designed to operate in a dynamically changing environment. Our main motivation is firstly to use MDE technology for the creation of the SLA contract and then to integrate MASs in order to control the quality of service contract and guarantee transparency and symmetry with respect to the SLA contract between prospective signatories.

차별화 서비스(DiffServ)는 효율적이며 규모성을 갖는 방법으로 서비스 품질(QoS)을 제공하는 기술이다. 그러나, 현재의 차별화 서비스 규격들은 완전한 QoS 관리 프레임워크와 구현 모델의 제공에는 취약한 실정이다. 본 논문은 차별화 서비스 망의 QoS를 관리하기 위하여 차별화 서비스 정책을 지원하는 정책 기반 차별화 서비스 QoS 관리 모델을 제안한다. 이 모델을 모델-뷰-컨트롤러(MVC) 구조를 따르며, EJB(Enterprise JavaBeans) 기술에 기반을 두고 있다. 우리의 모델에서 상위 레벨 차별화 서비스 QoS 정책들은 XML 스키마를 갖는 유효한 XML 문서들로 표현되고 EJB 기반 정책 서버 내에 하위 레벨 EJB 정책 번들로 변환된다. QoS 정책을 정의하기 위해 필요한 라우팅 형상과 라우터의 역할 정보 검출은 SNMP MIB-II를 사용하고, QoS 정책 분배와 모니터링은 SNMP DiffServ MIB를 사용한다. Differentiated Services (DiffServ) is a technique to provide Quality of Service (QoS) in an efficient and scalable way. However, current DiffServ specifications have limitations in providing the complete QoS management framework and its implementation model. This paper proposes a policy-based QoS management model that supports DiffServ policies for managing QoS of DiffServ networks. The management model conforms to Model-View-Controller (MVC) architecture, and is based on Enterprise JavaBeans (EJBs) technologies. In our model, high-level DiffServ QoS policies are represented as valid XML documents with an XML Schema and are translated to low-level EJB policy beans in the EJB-based policy server. The routing topology and role information required to define QoS policies is discovered by using SNMP MIB-II, and the QoS policy distribution and monitoring is accomplished by using SNMP DiffServ MIB.

Service level agreement (SLA) in cloud computing can be defined as a contractual agreement signed between cloud user and cloud provider in order to manage the quality of service (QoS) parameters which are the fundamental part of SLAs. The current dynamic SLA monitoring approaches have considered the cloud provider's perspective only. To take into consideration the user's perspective; this research proposes a dynamic SLA monitoring approach by generating new SLA terms based on analysing the SLA penalties. A new proposed trade-off mechanism is applied between monthly cost and QoS guarantee values. Thus; we propose a dynamic model for updating QoS parameters of SLA in cloud environment. Java language is used with a QoS measurement dataset to experiment the proposed approach. The current Static SLA (SSLA) approaches are compared with the proposed Dynamic SLA (DSLA) approach. The results of this experimental study show that the number of SLA violations in DSLA are less than the number of SLA violations in SSLA.

Service level agreement (SLA) in cloud computing can be defined as a contractual agreement signed between cloud user and cloud provider in order to manage the quality of service (QoS) parameters which are the fundamental part of SLAs. The current dynamic SLA monitoring approaches have considered the cloud provider's perspective only. To take into consideration the user's perspective; this research proposes a dynamic SLA monitoring approach by generating new SLA terms based on analysing the SLA penalties. A new proposed trade-off mechanism is applied between monthly cost and QoS guarantee values. Thus; we propose a dynamic model for updating QoS parameters of SLA in cloud environment. Java language is used with a QoS measurement dataset to experiment the proposed approach. The current Static SLA (SSLA) approaches are compared with the proposed Dynamic SLA (DSLA) approach. The results of this experimental study show that the number of SLA violations in DSLA are less than the number of SLA violations in SSLA.

A computational grid ensures the on-demand delivery of computing resources, in a security-aware, shared, scalable, and standards-based computing environment. A major concern is how to evolve a general and an encompassing framework that guarantees users' satisfaction measured as Quality of Services (QoS). To obtain a higher QoS, effective QoS perceived by subscribers (users) must conform to specified QoS agreements in the Service Level Agreements (SLAs) document--a legal contract between the Grid Services Provider (GSP) and users. Sometimes the effective user QoS does not conform to the specifications in the SLA because of the vagueness in linguistic definitions in the SLA. Existing approaches overcommitted resources to meet QoS. In this paper, we propose a fuzzy logic framework for calibrating a grid resources user-QoS that addresses the vagueness in linguistic definitions of the SLA document without overcommitting grid resources.

Utility computing enables the use of computational resources and services by consumers with service obligations and expectations defined in Service Level Agreements (SLAs). Parallel applications and workflows can be executed across multiple sites to benefit from access to a wide range of resources and to respond to dynamic runtime requirements. A utility computing provider has the difficult role of ensuring that all current SLAs are provisioned, while concurrently forming new SLAs and providing multiple services to numerous consumers. Scheduling to satisfy SLAs can result in a low return from a provider's resources due to trading off Quality of Service (QoS) guarantees against utilisation. One technique is to employ advance reservations so that an SLA aware scheduler can properly manage and schedule its resources. To improve system utilisation we exploit the principle that some consumers will be more flexible than others in relation to the starting or completion time, and that we can juggle the execution schedule right up until each execution starts. In this paper we present a QoS scheduler that uses SLAs to efficiently schedule advance reservations for computation services based on their flexibility. In our SLA model users can reduce or increase the flexibility of their QoS requirements over time according to their needs and resource provider policies. We introduce our scheduling algorithms, and show experimentally that it is possible to use flexible advance reservations to meet specified QoS while improving resource utilisation.

Service level agreement (SLA) is a formal contract between a service provider and a service consumer to guarantee the Quality of service (QoS) expectations, it is used in all areas of information technology, such as Cloud Computing, Internet of Things (IoT), networks and Web services. For IoT applications, the main challenges are: (1) how to describe the SLA terms, such as QoS properties, service levels, penalties in SLA violation, (2) how to monitor these terms, and (3) how to integrate an SLA into all the IoT application layers. Therefore, in this paper, we propose ML-SLA-IoT, a framework for SLA specification and monitoring. It covers the entire layers of an IoT application. It describes precisely QoS levels, provided services, and obligations. It differs from other SLA specification languages in the specification of user preferences, the use of microservices (for reusability, dynamism and ease of integration) and ML-SLA (multi-level metrics and QoS according to existing constraints and user preferences). Furthermore, ML-SLA-IoT monitors SLA terms in an automatic and decentralised manner using smart contracts and blockchain technologies without the intervention of the third-party. Finally, we present a comparative study and experiments with existing solutions regarding to some criteria for SLA specification and monitoring. Our results show that ML-SLA-IoT gives better performance in terms of dynamic pricing, obligation combination, and SLA monitoring.

Monitoring Quality of Service (QoS) compliance is an important procedure in web service environment. It determines whether users' expectations are met, and becomes the vital factor for them to decide whether to continue paying for the service or not. The monitoring is performed by checking the actual services performance against the QoS stated in Service Level Agreement (SLA). In relation to that, the need for monitoring vague QoS specifications in SLA has become more apparent nowadays. This paper reviews the published literature on web services QoS monitoring. A total of 60 selected articles were systematically analyzed. There were 23 of the articles selected through restrictive search criteria while the other 37 were selected based on unrestrictive search criteria. The review shows that little evidence exists on monitoring vague QoS specifications of web services. Providing ability for monitoring QoS that is specified vaguely in SLA could give new insights and implications to web services field. This paper concludes with some recommended future works to construct the theory and perform the empirical research.

Service Level Agreements (SLA) represents the principal means to control the Quality of Service (QoS). In cloud computing, various advanced SLA strategies are used; some techniques among others try to avoid the SLA violations. Taking into account the cloud consumer contextual parameters is a promising way to predict and avoid costly SLA violations. Therefore, in this paper, we propose a context-aware system for the SLA in order to guarantee the QoS. We create a contextual ontology to introduce the semantic meaning of the cloud consumer contextual parameters. In addition, using reasoning techniques, we (1) predict SLA violations and we (2) choose and apply the corrective actions in autonomous manner. This allows getting a proactive adjustment of the cloud service execution and respecting the SLA parameters.

This work presents a novel scheme for Service Level Agreements (SLAs) in a service-oriented architecture (SOA). An SLA is a contract that guarantees quality of service (QoS) between service providers and consumers. An SLA can be split into several parts for an SOA system which is consisting of different services. A split SLA is used to guarantee quality of services for one of services in an SOA system. However, these contract rules do not regulate follow-up process in services. SLA violations may occur consequently. For instance, interactions between services are not encrypted because the encryption parameter isn't included in the split SLA contract. Confidential data would be transmitted through unsafe channels. There would be a security issue of SLA Management for follow-up processes in an SOA system. The novel scheme in this work addresses these problems. Using SLAs management proposed in this work can identify the services that consumer needs and split the contracts for follow-up services. SLAs are not only guaranteed between service providers and consumers but also assured in follow-up processes. The proposed method improves the security and completeness of SLA using in an SOA system.

Now-a-days the web services are uprising technology which appeals lots of attention from both academic and industry. The quality of service has been one of the major challenges in the web services. If the web services become operational then the service providers with Service Level Agreement (SLA) need to consider and monitor with respect to the quality of web services and SLA. The most important factor is that to monitor and prevent the SLA intrusion in the composite web services. In the existing work the adaptation is done only at the instance level of the composition, for each level of composition the adaptation is done in each instance. Then the aggregated SLO's are defined over the number of instances which are out of scope and also the adaptation is not considered as permanent. In this PERvent (prediction and prevention based on event monitoring) framework is not supported for large number of adaptation action per the checkpoint because it is fully based on the number of checkpoints, and also it supports limited structural adaptation in the composition. The proposed work is to exclude these drawbacks by introducing the framework called Quality based dynamic composition (QDC) framework for monitoring the SLA parameter as well as monitoring Service Quality (QOS) Parameter for composite web service and also we will discuss the experimental results to prove how these approaches to monitor the Quality of Service (QOS) parameters for the composed web service.

Within a business environment, the quality of service (QoS) is one of the most important factors for differentiating between similar services. It is very important for service providers to control and manage the QoS for their offered services and for service consumers to validate the services they use. The Service Level Agreements (SLAs) plays an important role for maintaining the Quality of Service and help to improve the level of services being offered for service consumers to validate the services that are received. The SLAs can be described in different ways but there is no significant standard solution available for SLAs which could be integrated and interoperated effectively and automatically with the existing web service architecture. The purpose of this paper is to provide an efficient and automatic standard solution of SLAs which could sustain and maintain the QoS.