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scalability
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SDxVPN: A software-defined solution for VPN service providers
, Article Proceedings of the NOMS 2016 - 2016 IEEE/IFIP Network Operations and Management Symposium, 25 April 2016 through 29 April 2016 ; 2016 , Pages 180-188 ; 9781509002238 (ISBN) ; Taheri, N ; Khorsandi, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
BGP/MPLS IP VPN and VPLS services are considered to be widely used in IP/MPLS networks for connecting customers' remote sites. However, service providers struggle with many challenges to provide these services. Management complexity, equipment costs, and last but not least, scalability issues emerging as the customers increase in number, are just some of these problems. Software-defined networking (SDN) is an emerging paradigm that can solve aforementioned issues using a logically centralized controller for network devices. In this paper, we propose a SDN-based solution called SDxVPN which considerably lowers the complexity of VPN service definition and management. Our method eliminates...
Design for scalability in enterprise SSDs
, Article Parallel Architectures and Compilation Techniques - Conference Proceedings, PACT ; 24-27 August , 2014 , p. 417-429 ; ISSN: 1089795X ; ISBN: 9781450328098 ; Arjomand, M ; Sarbazi-Azad, H ; Sharif University of Technology
Abstract
Solid State Drives (SSDs) have recently emerged as a high speed random access alternative to classical magnetic disks. To date, SSD designs have been largely based on multi-channel bus architecture that confronts serious scalability problems in high-end enterprise SSDs with dozens of flash memory chips and a gigabyte host interface. This forces the community to rapidly change the bus-based inter-flash standards to respond to ever increasing application demands. In this paper, we first give a deep look at how different flash parameters and SSD internal designs affect the actual performance and scalability of the conventional architecture. Our experiments show that SSD performance improvement...
Topological properties of stretched graphs
, Article IEEE International Conference on Computer Systems and Applications, 2006, Sharjah, 8 March 2006 through 8 March 2006 ; Volume 2006 , 2006 , Pages 647-650 ; 1424402123 (ISBN); 9781424402120 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
IEEE Computer Society
2006
Abstract
We study a class of interconnection networks for multiprocessors, called the Stretched-G network, which is based on the base graph G by replacing each edge of the base network with an array of processors. Two interesting features of the proposed topology are its area-efficient VLSI layout and superior scalability over the underlying base network while preserving most of its desirable properties. We conduct a general study on the topological properties of stretched networks. We first obtain their basic topological parameters, after that we present an optimal routing algorithm. We also present a unified approach to obtain the topological properties and the VLSI-layout of an arbitrary stretched...
The discrepancy attack on polyshard-ed blockchains
, Article 2021 IEEE International Symposium on Information Theory, ISIT 2021, 12 July 2021 through 20 July 2021 ; Volume 2021-July , 2021 , Pages 2672-2677 ; 21578095 (ISSN); 9781538682098 (ISBN) ; Maddah Ali, M. A ; IEEE Information Theory Society; The Institute of Electrical and Electronics Engineers ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Sharding, i.e. splitting the miners or validators to form and run several subchains in parallel, is known as one of the main solutions to the scalability problems of blockchains. The drawback is that as the number of miners expanding each subchain becomes small, it becomes vulnerable to security attacks. To solve this problem, a framework, named as Ployshard, has been proposed in which each validator verifies a coded combination of the blocks introduced by different subchains, thus helping to protect the security of all subchains. In this paper, we introduce an attack on Ployshard, called the discrepancy attack, which is the result of malicious nodes controlling a few subchains and...
A matrix factorization model for hellinger-based trust management in social internet of things
, Article IEEE Transactions on Dependable and Secure Computing ; 2021 ; 15455971 (ISSN) ; Mahyar, H ; Movaghar, A ; Stanley, H. E ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
The Social Internet of Things (SIoT), integration of the Internet of Things and Social Networks paradigms, has been introduced to build a network of smart nodes that are capable of establishing social links. In order to deal with misbehaving service provider nodes, service requestor nodes must evaluate their trustworthiness levels. In this paper, we propose a novel trust management mechanism in the SIoT to predict the most reliable service providers for each service requestor, which leads to reduce the risk of being exposed to malicious nodes. We model the SIoT with a flexible bipartite graph, then build a social network among the service requestor nodes, using the Hellinger distance....
Rate-distortion optimization of scalable video codecs
, Article Signal Processing: Image Communication ; Volume 25, Issue 4 , 2010 , Pages 276-286 ; 09235965 (ISSN) ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
Abstract
In this paper joint optimization of layers in the layered video coding is investigated. Through theoretical analysis and simulations, it is shown that, due to higher interactions between the layers in a SNR scalable codec, this type of layering technique benefits most from joint optimization of the layers. A method for joint optimization is then proposed, and its compression efficiency is contrasted against the separate optimization and an optimized single layer coder. It is shown that, in joint optimization of SNR scalable coders when the quantization step size of the enhancement layer is larger than half the step size of the base layer, an additional improvement is gained by not sending...
A New Blockchain Scalability Scheme Based on Sharding
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Mohajery, Javad (Co-Supervisor)
Abstract
Designing a scalable protocol for the blockchain will reduce transaction fees and increase the use of cryptocurrencies for financial transactions. Increasing scalability means that if the investment of nodes increases or the number of network nodes increases, the security of the protocol and the decentralization of the network will be maintained and its throughput will increase. In this thesis, with the aim of increasing scalability, the scaling methods of layer one and layer two are examined and compared, and it is shown that sharding is a better method to achieve scalability. In sharding, nodes are divided into several shards (clusters) and each shard manages its own blockchain. The...
Performance evaluation of epidemic content retrieval in DTNs with restricted mobility
, Article IEEE Transactions on Network and Service Management ; Volume 16, Issue 2 , 2019 , Pages 701-714 ; 19324537 (ISSN) ; Entezari Maleki, R ; Chatzopoulos, D ; Hui, P ; Trivedi, K. S ; Movaghar, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In some applicable scenarios, such as community patrolling, mobile nodes are restricted to move only in their own communities. Exploiting the meetings of the nodes within the same community and the nodes within the neighboring communities, a delay tolerant network (DTN) can provide communication between any two nodes. In this paper, two analytical models based on stochastic reward nets (SRNs) are proposed to evaluate the performance of the epidemic content retrieval in such multi-community DTNs. Performance measures computed by the proposed models are the average retrieval delay and the average number of transmissions. The monolithic SRN model proposed in the first step is not scalable, in...
Enhancing Scalability in Software-defined Networks
, M.Sc. Thesis Sharif University of Technology ; Jahangir, Amir Hossein (Supervisor)
Abstract
Software Defined Networking (SDN) is an emerging paradigm which makes the network programmable by separating the control plane from data plane and makes both planes to work independently. There is a centralized controller and a programmable data plane in these networks architecture and forwarding data packets is realized by programming the data plane via an open interface called OpenFlow. OpenFlow is a communication protocol between control and data planes. The centralized architecture of these networks provides a global view of the underlying network to upper applications and brings numerous advantages such as routing, traffic engineering and QoS control. Despite these advantages there are...
Study on the Kinetics of Uranium Adsorption in the Stirred Reactors, and Search for the Scalable Kinetic Models for This
, M.Sc. Thesis Sharif University of Technology ; Otukesh, Mohammad (Supervisor) ; Khanchi, Alireza (Supervisor)
Abstract
One of the main uranium separations of ore that uranium percent application of enhanced design strategies in the industrial cracking furnaces are of practical interest for oil, gas and petrochemical industries. For such engineering purposes the exact simulation of temperature, species concentration and flow fields in the furnace is essential. In this paper, a study was performed to simulate 3D flue gas flow pattern, temperature and species concentration field in the radiation section of an industrial cracking furnace using the computational fluid dynamics (100-500) ppm technique. The steady-state Reynolds Averaged Navier–Stokes (Resin in pulp)equations were solved, in a finite volume scheme,...
Design and Evaluation of an Efficient Protocol for Temporal Scalable Video Streaming over Hybrid CDN-P2P Network
, M.Sc. Thesis Sharif University of Technology ; Akbari, Behzad (Supervisor) ; Khansari, Mohammad (Supervisor)
Abstract
Hybrid CDN-P2P architecture has been introduced to combine scalability advantage of P2P and reliability of CDN networks. Although it has been proved that CDN-P2P is more efficient than other architectures for live video streaming, there is still the question, “How is it possible to be more efficient in providing higher service quality?” Quality degradation in P2P and Hybrid CDN-P2P is mainly connected to the lack of exploiting role of peers’ heterogeneity in the system. Most of currently deployed live video streaming systems don’t adapt to bandwidth of the peers and just send one version of video to all users. To tackle this issue, many researches combine P2P solution with scalable video...
Scalable semi-supervised clustering by spectral kernel learning
, Article Pattern Recognition Letters ; Vol. 45, issue. 1 , August , 2014 , p. 161-171 ; ISSN: 01678655 ; Afsari, F ; Bagheri Shouraki, S ; Eslami, E ; Sharif University of Technology
Abstract
Kernel learning is one of the most important and recent approaches to constrained clustering. Until now many kernel learning methods have been introduced for clustering when side information in the form of pairwise constraints is available. However, almost all of the existing methods either learn a whole kernel matrix or learn a limited number of parameters. Although the non-parametric methods that learn whole kernel matrix can provide capability of finding clusters of arbitrary structures, they are very computationally expensive and these methods are feasible only on small data sets. In this paper, we propose a kernel learning method that shows flexibility in the number of variables between...
Introduction to non-volatile memory technologies
, Article Advances in Computers ; Volume 118 , 2020 , Pages 1-13 ; Sarbazi Azad, H ; Sharif University of Technology
Academic Press Inc
2020
Abstract
Dynamic Random Access Memory (DRAM) has been the leading main memory technology during the last four decades. In deep submicron regime, however, scaling DRAM comes with several challenges caused by charge leakage and imprecise charge placement. Phase Change Memory (PCM) technology is known as one of the most promising technologies to replace DRAM. Compared to competitive non-volatile memories like NAND Flash, Spin Transfer Torque random-access memory (STT-RAM), Magnetoresistive random-access memory (MRAM), PCM benefits from best attributes of fast random access, negligible leakage energy, superior scalability, high density, and operating in both Single-level Cell (SLC) and Multilevel Cell...
Scalable architecture for a contention-free optical network on-chip
, Article Journal of Parallel and Distributed Computing ; Volume 72, Issue 11 , 2012 , Pages 1493-1506 ; 07437315 (ISSN) ; Hessabi, S ; Sharif University of Technology
2012
Abstract
This paper proposes CoNoC (Contention-free optical NoC) as a new architecture for on-chip routing of optical packets. CoNoC is built upon all-optical switches (AOSs) which passively route optical data streams based on their wavelengths. The key idea of the proposed architecture is the utilization of per-receiver wavelength in the data network to prevent optical contention at the intermediate nodes. Routing optical packets according to their wavelength eliminates the need for resource reservation at the intermediate nodes and the corresponding latency, power, and area overheads. Since passive architecture of the AOS confines the optical contention to the end-points, we propose an electrical...
On Improving Scalability of Blockchain Systems Using Coding and Redundancy Methods
, M.Sc. Thesis Sharif University of Technology ; Motahhari, Abolfazl (Supervisor) ; Maddah Ali, Mohammad Ali (Supervisor)
Abstract
Blockchains are not scalable by design, and it is known to be the most important barrier in the way of development of these systems. One of the main approaches to this problem is sharding, that is under development in industry and academia. Sharding scales the system up by reducing redundancy, that makes blockchains vulnerable in terms of security. In this paper, we will study the effect of sharding on availability of these systems, and will show that sharding can magnify the unavailability of the service, and introduce an adversary threat model that takes real concerns of availability in today’s Internet like DoS attacks into account. We also introduce a basic unavailability-resistant...
All-Optical Scalable Multi-stage Interconnection Network for Data Centers
, M.Sc. Thesis Sharif University of Technology ; Koohi, Somayeh (Supervisor)
Abstract
According to the increasing amount of data exchanged among data centers, the need for speeding up and bandwidth and reduced power consumption has been increased. The information show that about 77% of the data is moved into the data centers. On the other hand, 10% of data center’s power consumption is used to data transmission. Improving the interconnection network of data centers can play an important role in reducing power consumption and speeding up. In recent years, optical interconnects have gained attention as a promising solution. Nevertheless, offering an all-optical and efficient architecture is an important issue. In this study, we intend to provide a multi-stage, all-optical...
A Data Replication Algorithm to Improve Performance of Cloud Data Centers
, M.Sc. Thesis Sharif University of Technology ; Movaghar, Ali (Supervisor)
Abstract
The daily growth of cloud computing usage for data based applications and Internet services has caused many challenges in the sense of storage cost, data access performance, QoS provision such as availability, scalability, pay-as-you-go model conformation and etc. Data replication is one of the most important mechanisms for data management in distributed systems. It creates some replicas of data and distributes them to the network. The number of replicas, the time for creating a new replica, the way of their distribution among the nodes and replica replacement strategy in the case of storage unavailability are some important challenges in data replication context. Replication is extensively...
Conditional Access System Design for DVB-T Receiver
,
M.Sc. Thesis
Sharif University of Technology
;
Hesabi, Shaahin
(Supervisor)
;
Sharifkhani, Mohammad
(Supervisor)
Abstract
In the Pay-TV industry, it is necessary to limit access of unauthorized users. Conditional Access System (CAS) is the solution. In the Pay-TV, the ability of instant join and leave operation is desirable for users. On the other hand, this characteristic is in contradiction with growth of user number.
Previous proposed conditional access systems address the requirement of pay-TV from several aspects. Key distribution management is on of them which plays a key role in the security and efficiency of a conditional access system. Re-examining the process of key distribution management make it possible to find a way to provide a greater flexibility for the users.
The purpose of this...
Previous proposed conditional access systems address the requirement of pay-TV from several aspects. Key distribution management is on of them which plays a key role in the security and efficiency of a conditional access system. Re-examining the process of key distribution management make it possible to find a way to provide a greater flexibility for the users.
The purpose of this...
Hierarchical Fat-tree Topology for an Optical Network-on-Chip
, M.Sc. Thesis Sharif University of Technology ; Hessabi, Shahin (Supervisor)
Abstract
With increasing number of processors on a chip, the role of interconnections becomes more important in both power consumption and bandwidth. As a result, in MultiProcessor System-on-Chip architectures, the design constraints will shift from "Computational Constraints" to "Communicational Constraints". Nowadays, optical information transfer is introduced as a suitable substitution for electrical interconnections in chips, which can eliminate their problems. Many different optical networks have been presented so far. These networks can be divided into two subcategories. Networks of the first category use an electrical infrastructure as well as optical one. Hence, the scalability of scheme is...
Design of a Scalable Optical Network-on-Chip by Reducing Role of Electrical Transactions
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
As the number of processing cores on a single chip continues to grow, the need for a high bandwidth, low power communication structure, will be the most important requirement of the next generation chip multiprocessors. Today, a major part of power consumption in multicore architectures belongs to interconnects. Due to these facts, reducing power consumption, as well as supporting high performance, is of major concern in these architectures. Optical interconnects have the potential to replace electrical wires to solve the bottleneck of communications in integrated circuits. Various routers and architectures with different points of view, have been recently designed considering existing...