With the magnificent expansion of network, it is getting more imperative to seek a means to deploy the network management tasks in a fast, unique and automated way. This paper proposes to use the integration of mobile agent technology (MAT) and Policy-based Network Management (PBNM) to achieve this flexibility and automation. PBNM, as a newly introduced but widely welcomed technology in the Internet world, can take over the overall management of IP network with MAT enabling the implementation of PBNM system. The work presented in this paper has been developed in the framework of the EU IST Project MANTRIP. A scenario for solving a practical network management challenge, i.e., inter-domain IP Virtual Private Network, is implemented, which shows how the integration of mobile agent technology and PBNM could be used to overcome many management problems inherent in traditional management approaches.

Peer-to-peer networks have widespread and got commonly used in our every day life. The maintenance strategy of overlays is a key factor in structured peer-to-peer networks. Most of these routing overlays scale well even for a very large number of nodes in static and quasi-static networks. However, providing good performance in dynamic network environments is still an open question. We analyse maintenance of routing overlays in structured P2P systems under churn. We exploit the inherent difference in the role of local (short-range) and long-range connections. We propose a dual strategy for the routing overlays: (i) we reuse strict, proactive and self-stabilizing short-range connection maintenance and (ii) we define a novel, loose and stochastic long-range connection maintenance mechanism, which can significantly reduce maintenance overhead in large networks with high churn rates without affecting routing performance. We use Kleinberg’s small worlds model to describe and (re)construct long-range connections. We formally describe the evolution of our proposed system under churn by a Markov chain model and we derive its steady state maintenance traffic (overhead). We formally show that our maintenance method scales logarithmically with the system’s size, which is the theoretical lower bound for maintenance traffic to ensure connectivity of the network. Finally, we numerically analyse overlay and maintenance behaviour using various protocol parameter settings and conclude that an overlay with our maintenance method is stable at very high levels of churn.

Networks are becoming service-aware implying that all relevant business goals pertaining to a service are fulfilled, and also the network resources are used optimally. Future Internet Networks (FIN) have time varying topology (e.g. such networks are envisaged in Autonomic Internet [1], FIND program [2], GENI program [3], FIRE program [4], Ambient Networks [5], Ad-hoc networks [6]) and service availability and service context change as nodes join and leave the networks. In this paper we propose and evaluate a new self-organising service management system that manages such changes known as the Overlay Management Backbones (OMBs). The OMB is a self-organising solution to the problem space in which each OMB node is dynamically assigned a different service context task. The selection of OMB nodes is conducted automatically, without the need of relatively heavy-weighted dynamic negotiations. Our solution relies on the scalability and dynamicity advantages of Distributed Hash Tables (DHTs). This system is needed to select continuously, automatically, and dynamically a set of network nodes, to become responsible for collecting the availability information of service context in the changing network. This solution advances the state of the art avoiding dynamic negotiations between all network nodes reducing management complexity and cost for bandwidth-limited environments.

This paper presents the CONTEXT framework for the creation, deployment and management of context-aware multimedia services using programmable network facilities. The Service Creation Layer (SCL) components of this framework allow the creation of the services using a service subscription server. Customisation and management are both supported by the policy-based paradigm. The Policy-Based Service Management (PBSM) layer components ensure efficient delivery and management of these services and the Execution Layer components guarantee the correct execution and assurance of the context-aware multimedia services over the network.

Ambient networks (ANs) are dynamically changing and heterogeneous as they consist of potentially large numbers of independent, heterogeneous mobile nodes, with spontaneous topologies that can logically interact with each other to share a common control space, known as the ambient control space. ANs are also flexible i.e. they can compose and decompose dynamically and automatically, for supporting the deployment of cross-domain (new) services. Thus, the AN architecture must be sophisticatedly designed to support such high level of dynamicity, heterogeneity and flexibility. We advocate the use of service specific overlay networks in ANs, that are created on-demand according to specific service requirements, to deliver, and to automatically adapt services to the dynamically changing user and network context. This paper presents a self-management approach to create, configure, adapt, contextualise, and finally teardown service specific overlay networks.

Overlay Networks have been designed as a promising solution to deliver new services via the use of intermediate nodes, acting as proxies or relays. This concept enables to hide the heterogeneity and variability of the underlying networks. In the Ambient Networks (ANs) project, the objectives are to study the composition and decomposition of services, the multi-radio interfaces, the user and network mobility and all the features that should address the networks dynamic, variability, change and so on. In this project, the concept of overlay networks has been selected as the means to deliver services, that should be adapted to end-users' context, regarding the access network, the location, the used device and the user's preferences. Obviously, since ANs are very dynamic, variable, the overlay network should be adaptable to fit the new environment. In this paper we present the architecture of this overlay network as well as the dynamic and secure deployment mechanisms which aim at improving the delivery of adapted services. The overlay network being created upon service providers request, an interface allowing this creation request and further configuration requests has been defined and is presented in this paper, the so-called Ambient Service Interface (ASI). Finally to prove the interest of our solution, an implementation of an IPTV services use-case is escribed.

Within the European research project ambient networks three reference points have been defined that determine the interactions and services an ambient network provides and fully describe it from an external perspective. In this paper, one of these reference points, the ambient service interface (ASI), is described in detail. The ASI is used for connecting external services to the ambient control space (ACS) of an ambient network and provides uniform access to ambient networks functionality from upper layers. After introducing the ASI main concepts, the new ambient networks service provisioning role model is presented. Examples of ASI primitives are given and a proposal for the realization of the ASI framework using web services is presented. The usage and implementation of the ASI in an IPTV usage scenario is given. Finally, the integration with IMS is discussed.

The paper presents the design and implementation of Ambient Service Interface (ASI) framework, which offers suitable level of flexibility and programmability to satisfy the requirements of Ambient Network applications. The direct access to ACS (Ambient Control Space) Functional Entities has been enabled by a hub-and-spoke server - ASB (ASI Switchboard), which supports required level of flexibility and programmability. The features of the proposed solution have been analyzed in context of Ambient Networks application. The Synapse-based Switchboard implementation is described. Next ASB activity scenario has been presented by simple case study, which concerns communication with context FE. The paper is ended with conclusions.

Existing research work on Distributed Hash Tables (DHTs) assume that, prior to actually establishing a DHT, large number potential member nodes would come together at one point and at one place, and would all agree on the characteristics of the DHT to-be-established. This paper presents DHT bootstrapping, which is a novel approach to enable secure, efficient and scalable deployment of DHTs in wireless networks, in particular in wireless networks with time-varying topology. Our solution is not restricted to a particular type of DHT implementation.

Ambient networks (ANs) introduce a new dynamic and flexible architecture for fixed and mobile networks. The environment is dynamic since they consist of various mobile nodes and flexible since ANs can compose and decompose dynamically and automatically with other ANs. The AN architecture must be sophisticatedly designed to support such high level of dynamicity, heterogeneity and flexibility. Composition and decomposition is performed at the network-level but since the network topology may change, the service delivery should also be adapted accordingly. Indeed, new services should be user-centric. In this paper, for delivering services adapted to the dynamically changing user and network context, we promote the use of service specific overlay networks in ANs that are created on- demand according to specific service requirements. This paper presents an autonomic approach to create, configure, adapt, contextualize, and finally teardown those context-aware overlay networks.

This paper summarizes and expands the ContextWare architecture proposed for context dissemination and aggregation for Ambient Networks European research project. ContextWare deals with sources of context, the way of acquiring context data from sensors, and its distribution to interested context consumers in an uniform form. Components of ContextWare architecture are described in details. Paper specifies Context Source, which is an abstraction of context provider, Context Manager, which handles high-level context aggregation and processing, Context Coordinator, which is used for handling large set of dynamic Context Sources, and Triggering, which assures context consistency. The collaboration of these components is illustrated with a scenario, which presents usage of ContextWare architecture within AN application. The system was successfully used in the Ambient Networks Project.

Extending the current use of the event-condition-action (ECA) logic of active databases for defining self-adaptation policy has been suggested; key research areas are adaptation policy definition, dynamic conflict detection and resolution. However, developing service-aware self-adaptation systems in heterogeneous and rapidly changing wireless networks such as ambient networks (ANs) is a challenging issue. This paper identifies that existing approaches suffer from the lack of a flexible management system to handle conflicting service adaptation policies; and often conflicting policies are simply ignored, which results in situations in which certain network conditions are not satisfied. In this paper, we present the ambient virtual pipe (AVP) platform, that uses an action object base (AOB) that enables flexible management of potentially conflicting adaptation policies. Two conflict resolution approaches, known as the AVP action prioritisation approach and the AVP composition approach, are also presented and discussed

Next generation services requiring adaptability to network and environment changes can be created with the use of flexible, self and service adaptable management overlays. This paper presents such a management overlay, the Ambient Virtual Pipe (AVP) in Ambient Networks. Contextualisation of an AVP enables it to achieve service adaptation in response to changes in context information. Contextualisation is achieved through interactions with ContextWare, an infrastructure which collects, manages and disseminates context.. The contextualisation of the AVP and the architecture and components of ContextWare, are presented along with a proof of concept prototype.

This paper presents a novel network context monitoring system, known as the context monitoring system (CMS), that is designed to accommodate the rapidly changing network context requirements and network context availability in dynamically (de)composing ambient networks (ANs). CMS is designed to support dynamic deployment, activation, and (re)configuration of context sensors in ANs in an efficient and scalable way, and to locate available distributed network context in a scalable and distributed manner once context sensors are deployed, in order to support subsequent efficient and scalable network context retrieval.

When different wireless networks come in close proximity there is often a need for them to logically combine, or compose. We focus on a known research problem particularly in Ambient Networks (ANs), where hetero-geneous Distributed Hash Tables (DHTs) contained in these wireless networks need to merge or divide as a result of these dynamic (de)composition processes, respectively. We present two novel DHT (de)composition models for ANs, known as absorption and gatewaying, that are designed to handle (de)composition of DHTs in different AN network environments, with minimal disturbance to existing member nodes.

Programmable context-ware services use context information and programmable networks technology in the provision of easily customised and personalised services, which can respond appropriately to changes in their environment. This paper presents one such service, which is used to enable the provision of VoIP services in crisis situations. This service, the context-aware VoIp (CaVoIP) service is built upon the CONTEXT platform, an innovative middleware designed for the creation, deployment and management of context-aware services. The platform consists of a programmable layer, a context-aware service engine and a policy-based service layer. The voice services in the CaVoIP service are provided by a session initiation protocol (SIP) platform called Siptrex. The result is an easily customised, flexible and scalable context-ware service, which suppresses, non-essential traffic during crisis situations allowing greater bandwidth for essential traffic.

While Grid services introduce efficiency in addressing the changing and often large resource demands of Grid applications, making the system context-aware takes the approach a step further by incorporating the important aspects of customisation and personalisation into Open Grid Services Architecture (OGSA) services. This is achieved by extending the concept of virtual organisations (VO) to Grid context, which link context information to users, policies and resources. Context is defined as any information that can be used to characterise the situation of an entity. When this information is modelled and properly managed, the OGSA services can become context-aware and context-aware services can be offered by the Grid.

In order to bring together the higher speed of WLAN and the wider coverage of GPRS, solution from service's perspective is necessary. And this kind of integrated service should be context-aware in order to automatically adapt itself to the changing environment. This paper proposes to explore the applicability of using network-centric context-aware service to integrate WLAN and GPRS network environments. Starting from typical scenario description and requirement analysis, a policy-based context model is presented, which takes into account the real implementation of context-aware service in the underlying networks. A context-aware service scenario called Modern Professor is explored to exemplify this methodology based on the policy-based context-aware service system architecture.

The convergence of wired and wireless network services is one of the driving forces behind next generation networks (NGN). These integrated services should be context-aware in order to automatically adapt themselves to the changing environment. Context can be defined as any information, obtained either explicitly or implicitly, that can be used to characterise one certain aspect of an entity involved in a specific application or network service. A context-aware service is one that uses such context for service provision. This paper proposes a policy based context-aware service methodology for next generation networks. A thorough consistency is expected to be achieved by this policy method where policies are well planned to run from context representation through services down to the underlying networks. A context-aware service scenario called the Super-mother is presented to exemplify this methodology based on the policy-based context-aware service system architecture. This paper presents work in an ongoing European Union IST project CONTEXT. 1. BACKGROUND AND RATIONALE The convergence of both fixed networks and wireless networks has attracted much research aiming to bring together the high speed of wired networks and the wider coverage of wireless networks (typically represented by GPRS/UMTS). As the hardware and protocols of wireless networks get mature, the demands from higher-level applications and services in integrated networks are rapidly growing, especially when wireless LAN (WLAN) technology becomes increasingly popular for providing IP connectivity and 3G is undergoing deployment stage. This paper tends to contribute to this literature from the services perspective by introducing the idea of context -awareness to the integrated services operating on next generation networks. Context refers to the physical and social situation in which computational devices are embedded [1]. A context-aware service (CAS) can be more flexible and autonomous so as to respond accordingly to the highly changing computational environments. For example, a mobile phone will vibrate rather than ring during a meeting, if the system knows the location of the mobile phone and the meeting schedule. While most of the research on context -aware computing focuses mainly on the human-computer interface (HCI) [1, 2], this paper tends to tackle context awareness from the perspective of networks, i.e., network-centric context -aware services. To facilitate the provision of context -aware services, both an appropriate infrastructure to gather, manage, and disseminate context ual information and the design and development of a context model are required. Policies are ideal for context modelling as they easily facilitate the implementation of context -aware services in the underlying networks where policy-based network management (PBNM) is widely regarded as a promising means. PBNM technology can relieve the network administrator of the burden of configuring every single device manually and it is more flexible since network elements can be reconfigured by just producing or changing policies [3, 4]. The policy-based method is well suited as context is usually complex, changing and layered. This paper is structured as follows. After the scenario description in section 2, section 3 defines and classifies context and describes the policy specification. Then the policy-based context modelling and the context aware service (CAS) system architecture are presented in Section 4 and 5 respectively. Section 6 presents the service implementation with the conclusions and future work in section 7. 2. SCENARIO DESCRIPTION A typical network-centric context -aware service called TEANU (Transparent Enterprise Access for Nomadic User) is described. Consider Katherine, a middle class graphic designer with 3 kids. Katherine works from home a few days a week, using her home network that is connected to her office network. On the due date of the project, Peter, her 9 year old son, fell ill and had to be brought to the hospital. The taxi that is taking them to the hospital is stuck in traffic and upon finishing her project she tries to send her work to the office, using her laptop and a GPRS mobile phone. Unfortunately, the bandwidth of the mobile network is insufficient, and transferring the 5GB file will take about 20 hours, far passing the deadline. However, she had subscribed to this new TEANU service that allows transparent roaming between GPRS and WLAN networks. When she arrives at the hospital the TEANU service found out that there was an appropriate wireless LAN (WLAN) network in the hospital. It dynamically switched the network connection to this faster wireless network and her work was submitted successfully before the deadline. This scenario is called the Super-mother scenario and will be used throughout the paper for exemplifying this policy based CAS over the NGN. 3. REQUIREMENTS ANALYSIS 3.1. Context Definition Schilit et al, [1] refer to context as location, identities of nearby people and objects, and changes to those objects. They claim that the important aspects of context are: where you are, who you are with, and what resources are nearby. The following definition for context will be used: Context is any information, obtained either explicitly or implicitly, that can be used to characterise a certain aspect of an entity involved in a specific application or network service. An entity can be a physical object such as a person, a place, a router, a 3G network gateway, a physical link, or a virtual object such as IPsec tunnel, SNMP agent. 3.2. Classification of Context Previous definitions of context seed our development of context types. Dey [2, 6] proposed, location, identity, environment time, and activity as basic context types for characterising the situation of a particular context entity, as depicted in Figure 1. This context classification clearly answers the questions of who (Identity), where (Location), when (Time), and what (Activity) for a specific context entity (ContextEntity). Furthermore, an object-oriented design of these context types can also be considered. As far as network-related context information is concerned, its categories follow the logically hierarchical structure of network as depicted in Figure 2. Entity Location Identity Time Activity at time of involved in identified by located at Person Device NetMngtStation Figure 1: Classification of Context in term of Entity static User Information SP Information Inter-domain Information Intra-domain Information