Lionel Sacks

A biologically-inspired clustering algorithm dependent on spatial data in sensor networks

Sensor networks in environmental monitoring applications aim to provide scientists with a useful spatio-temporal representation of the observed phenomena. This helps to deepen their understanding of the environmental signals that cover large geographic areas. In this paper, the spatial aspect of this data handling requirement is met by creating clusters in a sensor network based on the rate of change of an oceanographic signal with respect to space. Inspiration was drawn from quorum sensing, a biological process that is carried out within communities of bacterial cells. The paper demonstrates the control the user has over the sensitivity of the algorithm to the data variation and the energy consumption of the nodes while they run the algorithm.

A weakly coupled adaptive gossip protocol for application level active networks

With the sharp increase in heterogeneity and distribution of elements in wide-area networks, more flexible, efficient and autonomous approaches for management and information distribution are needed. This paper proposes a novel approach, based on gossip protocols and firefly synchronisation theory, for the management policy distribution and synchronisation over a number of nodes in an application level active network (ALAN). The work is presented in the context of the IST project ANDROID (Active Network Distributed Open Infrastructure Development), which is developing an autonomous policy-based management system for ALAN. The preliminary simulation results suggest that with the appropriately optimised parameters, the algorithms developed are scalable, can work effectively in a realistic random network, and allow the policy updates to be distributed efficiently throughout the active network with a lower latency than other similar types of gossip protocols.

A biologically-inspired approach to designing wireless sensor networks

In this paper, we contend that there are significant advantages in treating some classes of sensor networks as biological-like systems-both in structural design characteristics and in operational processes. We show how this design process leads to a sensor network system that is robust to topological changes, is scaleable and self-organising and has a number of other desirable features. The operating system kOS was designed to support the operation of distributed biologically-inspired algorithms, in order to accomplish tasks in a sensor network system. We look at the design of kOS and analyse its performance. The work presented has been implemented in an environmental monitoring project and has applications in other areas.

Policy-based management for ALAN-enabled networks

This paper presents the architecture, policy schema, and policy specifications necessary to accomplish effective management of the application level active networking (ALAN) environment. Using ALAN, developers can engineer applications through the network by utilising platforms (active servers) on which 3rd party software (Proxylets) can be dynamically loaded and run. Redirection of packets destined for active processing at the servers is performed by active routers. Management of such large, dynamic systems presents challenges to centralised approaches. Management based on policies locally interpreted in the context of local state is gaining acceptance as an alternative. The IST project ANDROID uses a flexible generic specification for policies, represented in XML, allowing a wide range of policies to be expressed and processed in a common framework. Policies given here focus on management of routers for VPN scenarios, the resource and security management of active servers running the Proxylets, and management of the information distribution mechanism. Preliminary results were demonstrated during the trial which included the scenario involving the inter-site connectivity and active server resource and security management.

Active Robust Resource Management in Cluster Computing Using Policies

We present an implementation of a policy-based management architecture for emerging communications and computing paradigms such as Active Networks and the Grid. To manage such open, highly distributed and decentralized environments, an approach based on policy concepts is adopted, allowing support for active, dynamic adaptability in network elements, services and end-user applications, as well as achieving decentralization and distribution. We present our flexible, extensible policy and event specifications in XML, and describe our management architecture. One key feature of our approach is the distributed infrastructure: the Directory and the Management Information Distribution system. The second feature is the Resource and Security Management elements residing on the multi-node managed systems. These combine to provide a light-weight, self-organizing management architecture. As an applications example, we describe the implementation of our management system applied to the Application Level Active Networking (ALAN) environment, implemented in the European Commission Information Society Technologies (IST) project ANDROID.

Integrity methodology for interoperable environments

Modern telecommunications systems are becoming increasingly complex, in both their internal construction and the degree of interconnectivity-and interdependence-between systems. This situation is exacerbated by regulatory demands for operator interworking and requirements for high-quality delivery to users. In this context, the crucial issue is the ability of systems to retain their operational state of high integrity. The number of integrity issues in such systems is vast, and these issues must be understood and managed throughout development, testing, interconnection, and maintenance. This article presents a framework for analyzing the integrity features of telecommunications systems, and elaborates on integrity-preserving policies that can be applied during system development and deployment. Moreover, a description of a case study based on ACTS project TRUMPET (DGXIIIB, AC112) is given.

Stigmergic Techniques for Solving Multi-constraint Routing for Packet Networks

In this paper we describe how stigmergic techniques can be used in packet networks that offer soft QoS services. The problem we are interested is the on-line version of computing routes to be established over a packet network, and the number of constraints imposed by the service is more that one. We investigate the scheme of the algorithm, the issues around the characteristics of the constraints and we give some simulation evidence of the working algorithm.

A self-synchronised scheme for automated communication in wireless sensor networks

An algorithm for self-scheduling of node access and self-configuration of routes to data collectors in wireless sensor networks is proposed and described. The algorithm relies on the robustness and stability of the self-synchronisation of unnamed pulse coupled oscillators. Results of an initial simulation of a protocol based on the algorithm are reported. The results indicate that the protocol is resilient in the presence of low levels of mobility and noise. Plans to perform more realistic future tests, including a full implementation, are outlined.

Security and resource policy-based mangagement architecture for ALAN servers

Application Layer Active Networks (ALAN) allow quick and efficient deployment, on the active servers, of user-customised services (proxylets). Programmability above the transport layer makes this approach distinct form other active network initiatives. This scenario raises the issues of efficient resource management on the active server. Moreover, the deployment of user-specified processes has to be highly secure so as not to harm the active server operator platform. The 1ST project ANDROID is using a flexible generic specification for policies, in XML, allowing a wide range of policies to be expressed and processed in a common framework. This paper presents the security and resource management architecture developed to support the application of the ANDROID policy-based principles to manage the ALAN servers. We present the architecture, as well as the sample policy sets. The prototype security and resource management implementation were demonstrated during two real-life trials and the results are presented here.

On power-laws in SDH transport networks

It has been previously demonstrated [Carlos Da Costa, April 2002] that Internet topologies which were once considered unstructured networks with no global design processes actually follow power-laws, both at the router level and AS (autonomous system) domain level. This discovery has very wide implications on network research as well as network and protocol design. The Internet is not the only network instance to exhibit power laws however; in this paper we present evidence for similar power laws also existing in transport layer topologies; in this case a real world deployed SDH (synchronous digital hierarchy) network. The existence of such traits is unexpected as transport technologies are planned and engineered, in contrast to the rather looser planning and dynamic routing of the Internet. SDH networks are globally designed with multiple hierarchical levels and a specific structure, whereas the Internet is a growing collection of networks under independent control. Data is presented to demonstrate the conformance to power laws of the SDH network, the possible effects of the physical layer and the extent to which the topology remains scale-free throughout the networks hierarchy. The possible sources of the traits are discussed and contrasted to those hypothesized for the Internet.