In distributed admission control (AC) schemes, handling concurrent AC decisions assumes a relevant role in avoiding over or false acceptance and, consequently, service quality degradation. This problematic is even more intricate in multiservice network environments where distinct service levels need to be fulfilled. This paper debates and points out solutions to mitigate the negative impact that distributed admission of flows might have on the service level guarantees provided to network customers. Keeping in mind that simplicity is a key factor for deployable AC solutions, we suggest and discuss the use of (i) a service-dependent concurrency index; (ii) a token-based system and (iii) a rate-based credit system, as alternative or complementary proposals to minimize or solve QoS degradation resulting from AC false acceptance.

The clear trend toward the integration of current and emerging applications and services in the Internet launches new demands on service deployment and management. Distributed service-oriented traffic control mechanisms, operating with minimum impact on network performance, assume a crucial role as regards controlling services quality and network resources transparently and efficiently. In this paper, we describe and specify a lightweight distributed admission control (AC) model based on per-class monitoring feedback for ensuring the quality of distinct service levels in multiclass and multidomain environments. The model design, covering explicit and implicit AC, exhibits relevant properties that allow managing quality of service (QoS) and service-level specifications (SLSs) in multiservice IP networks in a flexible and scalable manner. These properties, stemming from the way service-dependent AC and on-line service performance monitoring are proposed and articulated in the model’s architecture and operation, allow a self-adaptive service and resource management, while abstracting from network core complexity and heterogeneity. A proof of concept is provided to illustrate the AC criteria ability in satisfying multiple service class commitments efficiently. The obtained results show that the self-adaptive behavior inherent to on-line measurement-based service management, combined with the established AC rules, is effective in controlling each class QoS and SLS commitments consistently.

The use of Internet as an ubiquitous communication platform puts a strong demand on service providers regarding the assurance of multiple service levels consistently. Designing flexible and simple service-oriented management strategies is crucial to support multiconstained applications conveniently and to obtain a deployable and sustainable service quality offer in multiservice IP networks. In this context, this paper proposes the use of a self-adaptive QoS and SLS management strategy sustained by a service-oriented traffic admission control scheme to ensure the negotiated quality levels. A p roof-of-concept of the proposed strategy is provided, illustrating its ability to self-adapt and control efficiently distinct QoS requirements in multiservice IP networks.

This paper analyzes and discusses the role of a distributed and simple admission control (AC) model in achieving scalable management of multiple network service levels. The model design, covering explicit and implicit AC, exhibits relevant properties which allow managing QoS and SLSs in multiservice IP networks in a flexible and scalable manner. These properties stem from the way service-dependent AC and on-line service performance monitoring are proposed and articulated in the model's architecture and operation. The scalability debate, carried out at these two levels, highlights key steps toward performing self-adaptive service-oriented AC and low overhead multiservice monitoring. The performance evaluation results, illustrating the role and relevance of the defined AC rules, show that QoS and SLSs requirements can be efficiently satisfied or bounded, proving that the simplicity, flexibility and self-adaptability of the model can be explored to manage multiple service guarantees successfully.

In multiservice networks, admission control (AC) is a convenient means of assuring high quality communications by safeguarding enough availability for customer traffic. This can be particularly useful to preserve the quality of services such as IP telephony and video conferencing, and to ensure acceptable throughput to elastic flows. This paper tackles the problematic of performing implicit AC in multiservice networks, pointing out a flexible yet simple to deploy solution for controlling flows which do not explicitly send signaling admission requests. This allows to complement the explicit AC case, widening the ability to integrate services and applications in a transparent way. The versatility and self-adaptability of the proposed distributed AC criteria in ensuring the quality of multiple services is also proved.

The trend toward the integration of current and emerging applications and services in the Internet has launched new challenges regarding service deployment and management. Within service management, admission control (AC) has been recognized as a convenient mechanism to keep services under controlled load and assure the required QoS levels, bringing consistency to the services offered. In this context, this article discusses the role of AC in multiservice IP networks and surveys current and representative AC approaches. We address and compare the architectural principles of these AC approaches and their main features, virtues and limitations that impact on the quality control of network services. We identify important design aspects that contribute to the successful deployment of flexible and scalable AC solutions in multiservice networks.

This paper studies and discusses the presence of LRD in network traffic after classifying flows into traffic aggregates. Following DiffServ architecture principles, generic QoS application requirements and the transport protocol in use, a classification criterion of Internet traffic is established. Using fractal theory, the resulting traffic classes are analysed. The Hurst parameter is estimated and used as a measure of traffic burstiness and LRD in each traffic class. The traffic volume per class and per interface is also measured. The study uses real traffic traces collected at a University of Minho major backbone router in different periods of network activity.

Achieving an admission control strategy for CoS networks covering both intra-domain and end-to-end operation is still an open issue. This paper discusses how AC can be carried out without adding significant complexity to the network control plane and proposes a distributed service-oriented AC model for these networks. The model only involves the network edge nodes leaving the network core unchanged. Ingress nodes perform implicit or explicit service-dependent AC based on both QoS and SLSs utilization metrics, obtained through on-line edge-to-edge monitoring performed at egress nodes. From an end-to-end perspective, the flow request is used both for AC and available service computation. Relevant aspects of the model interrelated areas and implementation key points are also discussed.

We propose a lightweight traffic admission control scheme based on on-line monitoring which ensures multimedia services quality both intra-domain and end-to-end. The AC strategy is distributed, service-oriented and allows to control QoS and SLS without adding complexity to the network core. For each service class, AC decisions are driven by rate-based SLS control rules and QoS parameters control rules, defined and parameterized according to each service characteristics. These rules are essentially based on systematic on-line measurements of relevant QoS and performance parameters. Thus, from a practical perspective, we discuss and evaluate methodologies and mechanisms for parameter estimation. The AC criteria is evaluated as regards its ability to ensure service commitments while achieving high network utilization. The results show that the proposed model provides a good compromise between simplicity, service level guarantee and network usage, even for services with strict QoS requirements.

This paper evaluates the performance of a distributed and lightweight AC model based on per-class edge-to-edge monitoring feedback for ensuring the quality of multiple services in class-based IP networks. The model resorts to service-dependent AC rules for controlling QoS parameters and SLSs utilization, both intradomain and end-to-end. To provide a proof-of-concept of the proposed AC solution, a prototype of the AC model has been developed and tested using a simulation platform. The devised test scenarios aim at exploring the AC criteria's ability in satisfying each service class QoS levels and existing SLSs commitments. Generically, the results show that the proposed AC model, using a two-rule AC criterion defined on a service class basis, is able to control service levels and achieve high network utilization, without adding significant complexity to the network elements. The use of systematic edge-to-edge on-line monitoring and of a controlled degree of overprovisioning proved to be essential design aspects contributing for reaching a good compromise between simplicity and performance.