Cross-Layer Platform for Dynamic, Energy-Efficient Optical Networks

The design of the next-generation Internet infrastructure is driven by the need to sustain the massive growth in bandwidth demands. Novel, energy-efficient, optical networking technologies and architectures are required to effectively meet the stringent performance requirements with low cost and ultrahigh energy efficiencies. In this thesis, a cross-layer communications platform is proposed to enable greater intelligence and functionality on the physical layer. Providing the optical layer with advanced networking capabilities will facilitate the dynamic management and optimization of optical switching based on performance monitoring measurements and higher-layer attributes. The cross-layer platform aims to create a new framework for networks to incorporate packet-scale measurement subsystems and techniques for monitoring the health of the optical channel. This will allow for quality-of-service- and energy-aware routing schemes, as well as an enhanced awareness of the optical data signals. This thesis first presents the design and development of an optical packet switching fabric. Leveraging a networking test-bed environment to validate networking hypotheses, advanced switching functionalities are demonstrated, including the support for quality-of-service based routing and packet multicasting. The investigated cross-layering is based on emerging optical technologies, enabling packet protection techniques and packet-rate switching fabric reconfiguration. Coupled with fast performance monitoring, the platform will achieve significant performance gains within the endeavor of all-optical switching. Allowing for a more intelligent, programmable optical layer aims to support greater flexibility with respect to bandwidth allocation and potentially a significant reduction in the network's energy consumption. The ultimate deliverable of this work is a high-performance, cross-layer enabled optical network node. The experimental demonstration of an initial prototype creates a dynamic network element with distributed control plane management, featuring fast packet-rate optical switching capabilities and embedded physical-layer performance monitoring modules. The cross-layer box enables an intelligent traffic delivery system that can dynamically manipulate optical switching on a packet-granular scale. With the goal of achieving advanced multi-layer routing and control algorithms, the network node requires an intelligent co-optimization across all the layers. The proposed cross-layer design should drive optical technologies and architectures in an innovative way, in order to fulfill the void between the design of basic photonic devices and the networking protocols that use them. The performance of the entire network -- from the optical components, to the routing algorithms and user applications -- should be optimized in concert. This contribution to the area of cross-layer network design creates an adaptable optical pipe that is extremely flexible and intelligent aware of both the physical optical signals and higher-layer requirements. The impact of this work will be seen in the realization of dynamic, energy-efficient optical communication links in future networking infrastructures

Novel techniques in large scaleable ATM switches

Bibliography: p. 172-178.This dissertation explores the research area of large scale ATM switches. The requirements for an ATM switch are determined by overviewing the ATM network architecture. These requirements lead to the discussion of an abstract ATM switch which illustrates the components of an ATM switch that automatically scale with increasing switch size (the Input Modules and Output Modules) and those that do not (the Connection Admission Control and Switch Management systems as well as the Cell Switch Fabric). An architecture is suggested which may result in a scalable Switch Management and Connection Admission Control function. However, the main thrust of the dissertation is confined to the cell switch fabric. The fundamental mathematical limits of ATM switches and buffer placement is presented next emphasising the desirability of output buffering. This is followed by an overview of the possible routing strategies in a multi-stage interconnection network. A variety of space division switches are then considered which leads to a discussion of the hypercube fabric, (a novel switching technique). The hypercube fabric achieves good performance with an O(N.log₂N)²) scaling. The output module, resequencing, cell scheduling and output buffering technique is presented leading to a complete description of the proposed ATM switch. Various traffic models are used to quantify the switch's performance. These include a simple exponential inter-arrival time model, a locality of reference model and a self-similar, bursty, multiplexed Variable Bit Rate (VBR) model. FIFO queueing is simple to implement in an ATNI switch, however, more responsive queueing strategies can result in an improved performance. An associative memory is presented which allows the separate queues in the ATM switch to be effectively logically combined into a single FIFO queue. The associative memory is described in detail and its feasibility is shown by laying out the Integrated Circuit masks and performing an analogue simulation of the IC's performance is SPICE3. Although optimisations were required to the original design, the feasibility of the approach is shown with a 15Ƞs write time and a 160Ƞs read time for a 32 row, 8 priority bit, 10 routing bit version of the memory. This is achieved with 2µm technology, more advanced technologies may result in even better performance. The various traffic models and switch models are simulated in a number of runs. This shows the performance of the hypercube which outperforms a Clos network of equivalent technology and approaches the performance of an ideal reference fabric. The associative memory leverages a significant performance advantage in the hypercube network and a modest advantage in the Clos network. The performance of the switches is shown to degrade with increasing traffic density, increasing locality of reference, increasing variance in the cell rate and increasing burst length. Interestingly, the fabrics show no real degradation in response to increasing self similarity in the fabric. Lastly, the appendices present suggestions on how redundancy, reliability and multicasting can be achieved in the hypercube fabric. An overview of integrated circuits is provided. A brief description of commercial ATM switching products is given. Lastly, a road map to the simulation code is provided in the form of descriptions of the functionality found in all of the files within the source tree. This is intended to provide the starting ground for anyone wishing to modify or extend the simulation system developed for this thesis

Machine Learning for Multi-Layer Open and Disaggregated Optical Networks

L'abstract è presente nell'allegato / the abstract is in the attachmen

Dynamic LightPath allocation in WDM networks using an SDN controller

Core wavelength division multiplexed (WDM) networks are widely used to provide fixed physical connectivity and bandwidth to the logically connected upper electronic layer devices using optical signals. However, growing demands for bandwidth-intensive applications and cloud-based services push optical networks carriers' to provide scalable and flexible services dynamically. Software defined networking (SDN) has the potential to program electronic layers by dynamically controlling and managing network resources using SDN controller applications. SDN's on-demand characteristics combined with the optical circuit-switching can enable optical network service providers to customize their service provisioning dynamically to the user's requirements. They enable fast provision of new services, and minimize underutilization of resources. In this paper, a model is proposed to bring the dynamic allocation of resources which is a layer 2+ functionality, to the WDM layer using SDN. A middle-ware application based on SDN and OpenFlow for dynamic switching and provisioning of optical service is presented. The application abstracts the optical layer's connectivity, also accounting for the switching constraints. Details of the model's implementation are discussed considering classically used equipment and its performance in terms of CPU and memory utilization, topology emulation time, and latency is evaluated. Finally, the application is tested with a Cisco layer one switch. Performance results show that the latency doubles when increasing the number of fibers of an optical cross connect from 5 to 7 and keeping wavelengths equal to 8, with Clos fabric topology

Switching considerations in storage networks.

by Leung Yiu Tong.Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.Includes bibliographical references (leaves 96-98).Abstracts in English and Chinese.Chapter 1. --- Introduction --- p.1Chapter 1.1 --- Motivation --- p.1Chapter 1.2 --- Thesis Organization --- p.3Chapter 2. --- Storage Network Fundamentals --- p.4Chapter 2.1 --- Storage Network Topology --- p.4Chapter 2.1.1 --- Direct Attached Storage (DAS) --- p.5Chapter 2.1.2 --- Network Attached Storage (NAS) --- p.7Chapter 2.1.3 --- Storage Area Network (SAN) --- p.9Chapter 2.1.3.1 --- SAN and the Fibre Channel Protocol --- p.11Chapter 2.1.4 --- Summary on Storage Network Topology --- p.12Chapter 2.2 --- Storage Protocol --- p.15Chapter 2.2.1 --- Fibre Channel --- p.15Chapter 2.2.1.1 --- Fibre Channel over IP (FCIP) --- p.17Chapter 2.2.1.2 --- Internet Fibre Channel Protocol (iFCP) --- p.19Chapter 2.2.2 --- Internet SCSI (iSCSI) --- p.20Chapter 2.2.3 --- InfiniBand --- p.22Chapter 2.2.4 --- Review on Storage Network Protocol --- p.25Chapter 2.3 --- Standard Organization --- p.27Chapter 2.4 --- Summary --- p.28Chapter 3. --- Switching Design for Storage Networks --- p.30Chapter 3.1. --- Shared Bus Design --- p.32Chapter 3.2. --- Time Division Switch --- p.36Chapter 3.3. --- Share Buffer Memory Switch --- p.37Chapter 3.3.1 --- Parallel Memory Array --- p.40Chapter 3.3.2 --- Distributive Storage --- p.43Chapter 3.4. --- Crossbar Switch --- p.45Chapter 3.4.1 --- Arbitrated Crossbar vs. Buffered Crossbar --- p.46Chapter 3.4.1.1 --- Arbitrated Crossbar Switch --- p.47Chapter 3.4.1.2 --- Buffered Crossbar Switch --- p.48Chapter 3.4.2 --- Switch Scheduling --- p.49Chapter 3.4.2.1 --- Bipartite Matching --- p.50Chapter 3.4.2.2 --- Token-based Distributive Scheduling --- p.53Chapter 3.4.2.3 --- Resource Counting using Semaphore --- p.56Chapter 3.5. --- Algebraic Switches --- p.60Chapter 3.5.1 --- Switching by Conditionally Nonblocking Properties --- p.61Chapter 3.5.2 --- Self-Routing Mechanism with Zero-Bit Buffering --- p.64Chapter 3.5.3 --- Multistage Interconnection of Self-routing Concentrators --- p.69Chapter 3.6. --- Summary --- p.73Chapter 4. --- Investigating Switching Issue in Storage Networks --- p.74Chapter 4.1 --- Choosing a Suitable Switch --- p.74Chapter 4.2 --- Quality of Service (QoS) --- p.76Chapter 4.3 --- Multicasting --- p.77Chapter 4.3.1 --- Crossbar Switch --- p.78Chapter 4.3.2 --- Shared-Buffer Memory Switches --- p.80Chapter 4.3.3 --- Algebraic Switch --- p.82Chapter 4.3.4 --- Application on Multicast Transmission --- p.86Chapter 4.4 --- Load Balancing Mechanism --- p.87Chapter 4.5 --- Optimization on Storage Utilization --- p.91Chapter 4.6 --- Summary --- p.93Chapter 5. --- Conclusion and Summary of Original Contributions --- p.9

Simulation and analytical performance studies of generic atm switch fabrics.

As technology improves exciting new services such as video phone become possible and economically viable but their deployment is hampered by the inability of the present networks to carry them. The long term vision is to have a single network able to carry all present and future services. Asynchronous Transfer Mode, ATM, is the versatile new packet -based switching and multiplexing technique proposed for the single network. Interest in ATM is currently high as both industrial and academic institutions strive to understand more about the technique. Using both simulation and analysis, this research has investigated how the performance of ATM switches is affected by architectural variations in the switch fabric design and how the stochastic nature of ATM affects the timing of constant bit rate services. As a result the research has contributed new ATM switch performance data, a general purpose ATM switch simulator and analytic models that further research may utilise and has uncovered a significant timing problem of the ATM technique. The thesis will also be of interest and assistance to anyone planning on using simulation as a research tool to model an ATM switch

A likely geological record of deep tremor and slow slip events from a subducted continental broken formation.

open2noFluids in subduction zones play a key role in controlling seismic activity, drastically affecting the rheology of rocks, triggering mineral reactions, and lowering the effective stress. Fluctuating pore pressure is one important parameter for the switch between brittle and ductile deformation, thus impacting seismogenesis. Episodic tremor and slow slip events (ETS) have been proposed as a common feature of the geophysical signature of subduction zones. Their geological record, however, remains scanty. Only the detailed and further characterization of exhumed fossil geological settings can help fill this knowledge gap. Here we propose that fluctuating pore pressure linked to metamorphic dehydration reactions steered cyclic and ETS-related brittle and ductile deformation of continental crustal rocks in the subduction channel of the Apennines. Dilational shear veins and ductile mylonitic shear zones formed broadly coevally at minimum 1 GPa and 350 °C, corresponding to ~ 30–40 km depth in the subduction zone. We identify carpholite in Ca-poor metasediments as an important carrier of H2O to depths > 40 km in cold subduction zones. Our results suggest that the described (micro)structures and mineralogical changes can be ascribed to deep ETS and provide a useful reference for the interpretation of similar tectonic settings worldwide.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 839779.openGiuntoli, F., Viola, G.Giuntoli, F., Viola, G