Paris Flegkas

A management and control architecture for providing IP differentiated services in MPLS-based networks

As the Internet evolves toward the global multiservice network of the future, a key consideration is support for services with guaranteed quality of service. The proposed differentiated services framework is seen as the key technology to achieve this. DiffServ currently concentrates on control/data plane mechanisms to support QoS, but also recognizes the need for management plane aspects through the bandwidth broker. In this article we propose a model and architectural framework for supporting DiffServ-based end-to-end QoS in the Internet, assuming underlying MPLS-based explicit routed paths. The proposed integrated management and control architecture will allow providers to offer both quantitative and qualitative services while optimizing the use of underlying network resources.

On management technologies and the potential of Web services

From the early days of management research and standardization in the late 1980s, there has always been a quest for a management technology that would be general enough to be used for network, system, service, and distributed application management; efficient in terms of information retrieval time, computational resources required, and management traffic incurred; and easy to use in order to reduce development time and operational costs. From protocol-based approaches such as OSI management and SNMP, attention shifted to distributed object and Web-based approaches. Recently, XML-based approaches and, in particular, Web services have been emerging as a promising Internet-based technology that might also be used for management. In this article we survey first the key aspects of protocol and distributed object approaches to management. We subsequently examine Web services as a distributed object approach to management, and consider its suitability, usability, and performance in comparison to SNMP and CORBA.

A policy-based quality of service management system for IP DiffServ networks

Policy-based management can guide the behavior of a network or distributed system through high-level declarative directives that are dynamically introduced, checked for consistency, refined, and evaluated, resulting typically in a series of low-level actions. We actually view policies as a means of extending the functionality of management systems dynamically, in conjunction with preexisting hard-wired management logic. We first discuss the policy management aspects of architecture for managing quality of service in IP DiffServ networks as presented by Trimintzios et al. (see IEEE Commun. Mag., Special Issue in IP Operations and Management, vol.39, no.5, p.80-88, 2001), and focus on the functionality of the dimensioning and resource management aspects. We then present an analysis of the policies that can influence the dimensioning behavior as well as the inconsistencies that may be caused by the introduction of such policies. Finally, we describe the design and implementation of the generic policy consumer component and present the current implementation status.

Provisioning for interdomain quality of service: the MESCAL approach

This article presents an architecture for supporting interdomain QoS across the multi-provider global Internet. While most research to date has focused on supporting QoS within a single administrative domain, mature solutions are not yet available for the provision of QoS across multiple domains administered by different organizations. The architecture described in this article encompasses the full set of functions required in the management (service and resource), control and data planes for the provision of end-to-end QoS-based IP connectivity services. We use the concept of QoS classes and show how these can be cascaded using service level specifications (SLSs) agreed between BGP peer domains to construct a defined end-to-end QoS. We illustrate the architecture by describing a typical operational scenario.

Distributed Cache Management in Information-Centric Networks

The main promise of current research efforts in the area of Information-Centric Networking (ICN) architectures is to optimize the dissemination of information within transient communication relationships of endpoints. Efficient caching of information is key to delivering on this promise. In this paper, we look into achieving this promise from the angle of managed replication of information. Management decisions are made in order to efficiently place replicas of information in dedicated storage devices attached to nodes of the network. In contrast to traditional off-line external management systems we adopt a distributed autonomic management architecture where management intelligence is placed inside the network. Particularly, we present an autonomic cache management approach for ICNs, where distributed managers residing in cache-enabled nodes decide on which information items to cache. We propose four on-line intra-domain cache management algorithms with different level of autonomicity and compare them with respect to performance, complexity, execution time and message exchange overhead. Additionally, we derive a lower bound of the overall network traffic cost for a certain category of network topologies. Our extensive simulations, using realistic network topologies and synthetic workload generators, signify the importance of network wide knowledge and cooperation.

Policy conflict analysis for quality of service management

Policy-based management provides the ability to (re-) configure differentiated services networks so that desired quality of service (QoS) goals are achieved. Relevant configuration involves implementing network provisioning decisions, performing admission control, and adapting bandwidth allocation dynamically according to emerging traffic demands. A policy-based approach facilitates flexibility and adaptability in that the policies can be changed without changing the implementation. However, as with any other complex system, conflicts and inconsistencies may arise in the policy specification. In this work, we concentrate on the policy conflicts that may occur for static resource management aspects of QoS provisioning, known as network dimensioning. The paper shows how conflict detection can be achieved using event calculus in conjunction with abductive reasoning techniques to detect the existence of potential conflicts in partial specification and generate explanations for the conditions under which the conflicts arise. We finally present some conflict detection examples from our initial implementation of a policy conflict analysis tool. Although we focus on network dimensioning, many of the types of conflicts we illustrate could arise in other applications.

Pursuing a Software Defined Information-centric Network

The areas of Software-Defined Networking (SDN) and Information-Centric Networking (ICN) have gained increasing attention in the wider research community, while gaining credibility through corporate interest and investment. With the promise of SDN to simplify the deployment of alternative network architectures, the question arises how SDN and ICN could concretely be combined, deployed and tested. In this paper, we address this very question within a particular architectural context for ICN. We outline a possible realization in a novel design for ICN solutions and point to possible test bed deployments for future testing.

End-to-end quality of service provisioning through inter-provider traffic engineering

This paper addresses the issue of delivering solutions that will enable the incremental implementation of inter-domain quality of service (QoS) in the multi-provider commercial Internet. The paper first introduces a holistic architecture that describes the key functions required to support inter-domain QoS, and then proceeds to present results from two major components of the architecture. A genetic algorithm for QoS-aware offline inter-domain traffic engineering is first presented, and it is shown through simulation studies how this can optimise the apportionment of QoS provisioning between adjacent domains. Secondly, QoS enhancements to BGP are proposed and the results of a testbed implementation are described, demonstrating how this QoS-enhanced BGP can deliver inter-domain QoS routing.

Dynamic Policy Analysis and Conflict Resolution for DiffServ Quality of Service Management

Policy-based dynamic resource management may involve interaction between independent decision-making components which can lead to conflicts. For example, conflicts can occur between the policies for allocating resources and those setting quotas for users or classes of service. These policy conflicts cannot be detected by static analysis of the policies at specification-time as the conflicts arise from the current state of the resources within the system and so can only be detected at run-time. In this paper we use policies related to quality of service (QoS) provisioning for configuring differentiated services (DiffServ) networks to illustrate techniques for the dynamic detection and resolution of conflicts. Configuration includes implementing network provisioning decisions, performing admission control, and adapting bandwidth allocation dynamically according to emerging traffic demands. We identify possible conflicts between policies that manage the allocation of resources, and we also investigate conflicts that may arise between these policies and higher-level directives refined at the dynamic resource management level, acting as constraints. The paper shows how event calculus can be used to detect conflicts, focusing on the ones that emerge at run-time, and provides an approach for specifying policies to automate conflict resolution. The latter is demonstrated through our initial implementation of a dynamic conflict analysis tool

Using linear temporal model checking for goal-oriented policy refinement frameworks

Policy refinement is meant to derive lower-level policies from higher-level ones so that these more specific policies are better suited for use in different execution environments. Although it has been recognized as crucial, it has received relatively little attention. We present a policy refinement framework grounded in goal-elaboration methodologies and reactive systems analysis. Through linear-time model checking, we obtain system trace executions aimed at fulfilling lower-level goals refined with the KAOS goal-elaboration method. From system executions, we abstract managed entities, conditions and actions to encode the refined policies. We present our framework and provide a refinement scenario applied to the DiffServ QoS management domain.