Architecture, design, and modeling of the OPSnet asynchronous optical packet switching node

An all-optical packet-switched network supporting multiple services represents a long-term goal for network operators and service providers alike. The EPSRC-funded OPSnet project partnership addresses this issue from device through to network architecture perspectives with the key objective of the design, development, and demonstration of a fully operational asynchronous optical packet switch (OPS) suitable for 100 Gb/s dense-wavelength-division multiplexing (DWDM) operation. The OPS is built around a novel buffer and control architecture that has been shown to be highly flexible and to offer the promise of fair and consistent packet delivery at high load conditions with full support for quality of service (QoS) based on differentiated services over generalized multiprotocol label switching

Feeling the squeeze? Tabbies or tigers: the case of social enterprises contracting in the fields of recycling and work integration

Current UK policy is encouraging the identification, emergence, transmutation or invention of third sector organisations that will have a social enterprise orientation with a particular focus on them as vehicles for the delivery of public services (Audit Commission 2005). This can be seen as part of the new governance agenda (Taylor, Wilkinson and Craig 2001, Kendal 2003, Stoker 2004) the form of which is still emergent. One view of governance refers to a 'hollowing out' of state powers (Rhodes, 1997) and a shift from state control to co-ordination using mechanisms such as networks and partnerships to bring together the public, private and third sector as well as community actors and citizens in reforming services. Local Authority white paper (2006) promised further decentralisation moving functions downwards to special purpose bodies and outwards to agencies and communities. The new Local Government White Paper emphasises the role of community engagement, partnership arrangements and devolved budgets with voluntary organisations at the local level (NCVO 2006: 2-3). Such processes are aimed both at both private and third sector providers. In this new distributed system of governance partnership and collaboration plays an important role in the implementation of social goods although these processes are never unproblematic (Huxham & Vangen 2000; Taylor Taylor, Wilkinson and Craig 2001). Nevertheless the contracting out processes continue to gather speed: with recycling and waste, care, leisure services, work advice, health services, prison and probation at various stages in the continuum of change. Against this background the role and form of social enterprise organisations appears at times to be assumed to be 'heterogeneous' and 'good' with all organisations tending towards similar development trajectories with uniform support needs. What is often not distinguished so clearly are the differing types of social enterprise; the different sub-sectors of the economy they are operating in; the variety of markets and funding regimes they are involved in; the different partnership regimes they are embedded within; and their different cultures and connection to local communities. All of these factors have implications for what types of organisations (large/small social enterprise; local/national organisations, and even social enterprise or private organisation) are favoured in the contracting processes and how such processes may affect their wider mission and ethos. Social enterprises are sometimes treated by policy makers, and at times by leaders, practitioners and researchers within the sector as if they were one thing. Crudely we might say they are treated as if they are all cats when in reality some are tigers and some are tabbys – with every breed in between. Nevertheless, despite the heterogeneity of the social enterprise scene we are seeing evidence of a convergence of form in contracting processes which, we argue, tends to favour the tigers and squeeze the tabbys. This paper reports on recent empirical research and analysis in 2 sub fields of social enterprise activity: (a) the delivery of waste and recycling services (Slater 2006) and (b) the delivery of work integration and advice activities for the disadvantaged (Aiken 2006, 2007)

Beyond 5G Domainless Network Operation enabled by Multiband: Toward Optical Continuum Architectures

Both public and private innovation projects are targeting the design, prototyping and demonstration of a novel end-to-end integrated packet-optical transport architecture based on Multi-Band (MB) optical transmission and switching networks. Essentially, MB is expected to be the next technological evolution to deal with the traffic demand and service requirements of 5G mobile networks, and beyond, in the most cost-effective manner. Thanks to MB transmission, classical telco architectures segmented into hierarchical levels and domains can move forward toward an optical network continuum, where edge access nodes are all-optically interconnected with top-hierarchical nodes, interfacing Content Delivery Networks (CDN) and Internet Exchange Points (IXP). This article overviews the technological challenges and innovation requirements to enable such an architectural shift of telco networks both from a data and control and management planes

Design issues in quality of service routing

The range of applications and services which can be successfully deployed in packet-switched networks such as the Internet is limited when the network does nor provide Quality of Service (QoS). This is the typical situation in today's Internet. A key aspect in providing QoS support is the requirement for an optimised and intelligent mapping of customer traffic flows onto a physical network topology. The problem of selecting such paths is the task of QoS routing QoS routing algorithms are intrinsically complex and need careful study before being implemented in real networks. Our aim is to address some of the challenges present m the deployment of QoS routing methods. This thesis considers a number of practical limitations of existing QoS routing algorithms and presents solutions to the problems identified. Many QoS routing algorithms are inherently unstable and induce traffic fluctuations in the network. We describe two new routing algorithms which address this problem The first method - ALCFRA (Adaptive Link Cost Function Routing Algorithm) - can be used in networks with sparse connectivity, while the second algorithm - CAR (Connectivity Aware Routing) - is designed to work well in other network topologies. We also describe how to ensure co-operative interaction of the routing algorithms in multiple domains when hierarchial routing is used and also present a solution to the problems of how to provide QoS support m a network where not all nodes are QoS-aware. Our solutions are supported by extensive simulations over a wide range of network topologies and their performance is compared to existing algorithms. It is shown that our solutions advance the state of the art in QoS routing and facilitate the deployment of QoS support in tomorrow's Internet

Scalable QoS-aware Mobility for Future Mobile Operators

Telecom operators and Internet service providers are heading for a new shift in communications paradigms. The forthcoming convergence of cellular and wireless data networks is often manifested in an “all IP approach” in which all communications are based on an end-to-end IP protocol framework. The approach to network design becomes user and service-centered, so that continuous reachability of mobile users and sustained communication capabilities are default requirements for a prospective architecture. In this article, we describe a network architecture which is able to provide seamless communication mobility, triggered either by the user or by the network, across multiple technologies. The architecture allows for media independent handovers and supports optimized mobility and resource management functions. The main focus of the article is on major technical highlights of mobility and quality-of-service (QoS) management subsystems for converged networks.Publicad