TCP throughput guarantee in the DiffServ Assured Forwarding service: what about the results?

Since the proposition of Quality of Service architectures by the IETF, the interaction between TCP and the QoS services has been intensively studied. This paper proposes to look forward to the results obtained in terms of TCP throughput guarantee in the DiffServ Assured Forwarding (DiffServ/AF) service and to present an overview of the different proposals to solve the problem. It has been demonstrated that the standardized IETF DiffServ conditioners such as the token bucket color marker and the time sliding window color maker were not good TCP traffic descriptors. Starting with this point, several propositions have been made and most of them presents new marking schemes in order to replace or improve the traditional token bucket color marker. The main problem is that TCP congestion control is not designed to work with the AF service. Indeed, both mechanisms are antagonists. TCP has the property to share in a fair manner the bottleneck bandwidth between flows while DiffServ network provides a level of service controllable and predictable. In this paper, we build a classification of all the propositions made during these last years and compare them. As a result, we will see that these conditioning schemes can be separated in three sets of action level and that the conditioning at the network edge level is the most accepted one. We conclude that the problem is still unsolved and that TCP, conditioned or not conditioned, remains inappropriate to the DiffServ/AF service

An adaptive policy-based framework for network services management

This paper presents a framework for specifying policies for the management of network services. Although policy-based management has been the subject of considerable research, proposed solutions are often restricted to condition-action rules, where conditions are matched against incoming traffic flows. This results in static policy configurations where manual intervention is required to cater for configuration changes and to enable policy deployment. The framework presented in this paper supports automated policy deployment and flexible event triggers to permit dynamic policy configuration. While current research focuses mostly on rules for low-level device configuration, significant challenges remain to be addressed in order to:a) provide policy specification and adaptation across different abstraction layers; and, b) provide tools and services for the engineering of policy-driven systems. In particular, this paper focuses on solutions for dynamic adaptation of policies in response to changes within the managed environment. Policy adaptation includes both dynamically changing policy parameters and reconfiguring the policy objects. Access control for network services is also discussed.Accepted versio

Enabling self-adaptive QoE/QoS control

Handling quality requirements of multimedia services and the expectations of end-users regarding the perceived service quality is currently a major issue for service providers in order to sustain service diversity and improve competitiveness. In this context, this paper presents ongoing work toward a service-oriented architecture for QoE/QoS evaluation and control, which can be deployed to assist the provision of multi-constrained services. Considering the users' QoE perspective and the negotiated service levels, the architecture lays on per service class online monitoring to assist self-adaptive control of multimedia flows entering the network. To perform online monitoring, a distributed and versatile QoS monitoring tool oriented to multiservice networks is proposed. Preliminary results shows that the presented control strategy is effective in providing consistent quality levels to heterogeneous services

LC-PCN: The Load Control PCN Solution

There is an increased interest of simple and scalable resource provisioning solution for Diffserv network. The Load Control PCN (LC-PCN) addresses the following issues:\ud o Admission Control for real time data flows in stateless Diffserv Domains\ud o Flow Termination: Termination of flows in case of exceptional events, such as severe congestion after re-routing.\ud Admission control in a Diffserv stateless domain is a combination of:\ud o Probing, whereby a probe packet is sent along the forwarding path in a network to determine whether a flow can be admitted based upon the current congestion state of the network\ud o Admission Control based on data marking, whereby in congestion situations the data packets are marked to notify the PCN-egress-node that a congestion occurred on a particular PCN-ingress-node to PCN-egress-node path.\ud \ud The scheme provides the capability of controlling the traffic load in the network without requiring signaling or any per-flow processing in the PCN-interior-nodes. The complexity of Load Control is kept to a minimum to make implementation simple.\u

Self-adaptive distributed management of QoS and SLSs in multiservice networks

Apresentação efectuada na International Conference on Integrated Management (IM 2005), Nice, France, May 2005.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 transparent and efficiently. In this way, we describe and specify a lightweight distributed admission control (AC) model which provides an uniform solution for managing QoS and SLSs in multiclass and multidomain environments. Taking advantage of the consensual need of on-line service monitoring and traffic control at the network edges, AC decisions are driven by feedback from systematic edge-to-edge measurements of relevant QoS parameters for each service type and SLS utilization. This allows self-adaptive service and resource management, while abstracting from network core complexity and heterogeneity. In this paper, introducing an expressive notation, we specify the high-level entities for multiservice provisioning in a domain and formalize service-dependent AC equations to assure both intra and interdomain model operation. A proof-of-concept of the AC criteria effectiveness in satisfying each service class commitments while achieving high network utilization is provided through simulation

Wireless industrial monitoring and control networks: the journey so far and the road ahead

While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks