Showing papers on "Overlay network published in 2020"

Towards distributed SDN: mobility management and flow scheduling in software defined urban IoT

Abstract: The growth of Internet of Things (IoT) devices with multiple radio interfaces has resulted in a number of urban-scale deployments of IoT multinetworks, where heterogeneous wireless communication solutions coexist (e.g., WiFi, Bluetooth, Cellular). Managing the multinetworks for seamless IoT access and handover, especially in mobile environments, is a key challenge. Software-defined networking (SDN) is emerging as a promising paradigm for quick and easy configuration of network devices, but its application in urban-scale multinetworks requiring heterogeneous and frequent IoT access is not well studied. In this paper we present UbiFlow, the first software-defined IoT system for combined ubiquitous flow control and mobility management in urban heterogeneous networks. UbiFlow adopts multiple controllers to divide urban-scale SDN into different geographic partitions (assigning one controller per partition) and achieve distributed control of IoT flows. A distributed hashing based overlay structure is proposed to maintain network scalability and consistency. Based on this UbiFlow overlay structure, the relevant issues pertaining to mobility management such as scalable control, fault tolerance, and load balancing have been carefully examined and studied. The UbiFlow controller differentiates flow scheduling based on per-device requirements and whole-partition capabilities. Therefore, it can present a network status view and optimized selection of access points in multinetworks to satisfy IoT flow requests, while guaranteeing network performance for each partition. Simulation and realistic testbed experiments confirm that UbiFlow can successfully achieve scalable mobility management and robust flow scheduling in IoT multinetworks; e.g., 67.21 percent throughput improvement, 72.99 percent reduced delay, and 69.59 percent jitter improvements, compared with alternative SDN systems.

An efficient energy-aware routing scheme for cloud-assisted MANETs in 5G

Abstract: Energy-Saving techniques for mobile communication systems has recently received a great deal of attention in Fifth Generation (5G) networks. The Device-to-Device (D2D) communication in 5G networks has increased number of users and the data transmission rate among the mobile nodes in Cloud Assisted-Mobile Ad Hoc Networks (CA-MANETs). However, the connection between these mobile nodes and peer nodes has to frequently renew due to mobility, link failure, routing overhead and low battery power. During this period, it consumes high energy in searching and linking the mobile nodes. Hence, this research work attempts to reduce the energy consumption by proposing an Energy-Efficient Cloud-Assisted Routing Mechanism (EECRM) for CA-MANETs. Energy consumption is minimized by performing fast local route recovery among mobile nodes and peer nodes. If the link failure occurs, the backup nodes are identified by neighbour nodes and these backup nodes form an overlay that provides the coverage and this overlay network consumes less energy in routing. The results obtained from this proposed routing algorithm provides better performance in terms of less energy consumption, residual energy and network lifetime when compared with other existing network models and routing protocols.

Particle: ephemeral endpoints for serverless networking

Abstract: Burst-parallel serverless applications invoke thousands of short-lived distributed functions to complete complex jobs such as data analytics, video encoding, or compilation. While these tasks execute in seconds, starting and configuring the virtual network they rely on is a major bottleneck that can consume up to 84% of total startup time. In this paper we characterize the magnitude of this network cold start problem in three popular overlay networks, Docker Swarm, Weave, and Linux Overlay. We focus on end-to-end startup time that encompasses both the time to boot a group of containers as well as interconnecting them. Our primary observation is that existing overlay approaches for serverless networking scale poorly in short-lived serverless environments. Based on our findings we develop Particle, a network stack tailored for multi-node serverless overlay networks that optimizes network creation without sacrificing multi-tenancy, generality, or throughput. When integrated into a serverless burst-parallel video processing pipeline, Particle improves application runtime by 2.4--3X over existing overlays.

Mapping the Interplanetary Filesystem

Abstract: The Interplanetary Filesystem (IPFS) is a distributed data storage service frequently used by blockchain applications and for sharing content in a censorship-resistant manner. Data is distributed within an open set of peers using a Kademlia-based distributed hash table (DHT). In this paper, we study the structure of the resulting overlay network, as it significantly influences the robustness and performance of IPFS. We monitor and systematically crawl IPFS' DHT towards mapping the IPFS overlay network. Our measurements found an average of 44474 nodes at every given time. At least 52.19% of these reside behind a NAT and are not reachable from the outside, suggesting that a large share of the network is operated by private individuals on an as-needed basis. Based on our measurements and our analysis of the IPFS code, we conclude that the topology of the IPFS network is, in its current state, closer to an unstructured overlay network than it is to a classical DHT. While such a structure has benefits for robustness and the resistance against Sybil attacks, it leaves room for improvement in terms of performance and query privacy.

Vickrey Auction-Based Secondary Relay Selection in Cognitive Hybrid Satellite-Terrestrial Overlay Networks With Non-Orthogonal Multiple Access

Abstract: In this letter, we investigate the Vickrey auction-based secondary relay selection in cognitive hybrid satellite-terrestrial overlay networks (CHSTONs) with non-orthogonal multiple access (NOMA). We analyze a cooperative spectrum sharing scheme for a multi-potential secondary relay selection scenario, in which the Vickrey auction is introduced to achieve an efficient secondary relay selection by one shot within the distributed computation. Both the decode-and-forward (DF) and amplify-and-forward (AF) protocols are considered for the relay to retransmit the primary user’s message, separately. Besides, the NOMA scheme is implemented to increase the total capacity in the second temporal phase. Finally, simulation results validate that the proposed auction-based approach is more effective than conventional approaches in secondary relay selection. Also, the influence of key factors on the performance of the auction mechanism is analyzed by the simulations.

Performing in-line service in public cloud

Abstract: Some embodiments provide a novel way to insert a service (e.g., a third party service) in the path of a data message flow, between two machines (e.g., two VMs, two containers, etc.) in a public cloud environment. For a particular tenant of the public cloud, some embodiments create an overlay logical network with a logical overlay address space. To perform a service on data messages of a flow between two machines, the logical overlay network passes to the public cloud's underlay network the data messages with their destination address (e.g., destination IP addresses) defined in the logical overlay network. The underlay network (e.g., an underlay default downlink gateway) is configured to pass data messages with such destination addresses (e.g., with logical overlay destination addresses) to a set of one or more service machines. The underlay network (e.g., an underlay default uplink gateway) is also configured to pass to the particular tenant's public cloud gateway the processed data messages that are received from the service machine set and that are addressed to logical overlay destination addresses. The tenant's public cloud gateway is configured to forward such data messages to a logical forwarding element of the logical network, which then handles the forwarding of the data messages to the correct destination machine.

SD-WAN: An Open-Source Implementation for Enterprise Networking Services

Abstract: A reliable Wide Area Network (WAN) has become a necessity for businesses enterprises to transmit critical data between multiple branches and to increase their revenues. Software-Defined Wide Area Networking (SD-WAN) is an emerging paradigm that introduces the advantages of Software Defined Networking (SDN) into Enterprise Networking (EN). SD-WAN can support differentiated services over public WAN by dynamically changing the flow forwarding rules over an overlay network based on monitoring data and service requirements. This paper proposes an early implementation of SD-WAN based on open source components, such as OpenDaylight as SDN_controller, OpenvSwitch (OvS) and a set of services for network monitoring and policy-based path selection. We present a demo-test in a simple emulated but realistic network environment, showing new features and advantages for the enterprise in terms of resource optimization.

Efficient Provision of Service Function Chains in Overlay Networks using Reinforcement Learning

Abstract: Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) technologies facilitate deploying Service Function Chains (SFCs) at clouds in efficiency and flexibility. However, it is still challenging to efficiently chain Virtualized Network Functions (VNFs) in overlay networks without knowledge of underlying network configurations. Although there are many deterministic approaches for VNF placement and chaining, they have high complexity and depend on state information of substrate networks. Fortunately, Reinforcement Learning (RL) brings opportunities to alleviate this challenge as it can learn to make suitable decisions without prior knowledge. Therefore, in this paper, we propose an RL approach for efficient SFC provision in overlay networks, where the same VNFs provided by multiple vendors are with different performance. Specifically, we first formulate the problem into an Integer Linear Programming (ILP) model for benchmarking. Then, we present the online SFC path selection into a Markov Decision Process (MDP) and propose a corresponding policy-gradient-based solution. Finally, we evaluate our proposed approach with extensive simulations with randomly generated SFC requests and a real-world video streaming dataset, and implement an emulation system for feasibility verification. Related results demonstrate that performance of our approach is close to the ILP-based method and better than deep Q-learning, random, and load-least-greedy methods.

QROUTE: An Efficient Quality of Service (QoS) Routing Scheme for Software-Defined Overlay Networks

Abstract: Many computer network applications impose constraints for multiple quality of service (QoS) metrics, e.g., delay, packet loss, bandwidth, and jitter. These QoS constraints cannot be guaranteed by the Internet due to its best-effort service model. Overlay networks have been an effective technique at the application layer to support multiple QoS constraints of networking applications. In software-defined overlay networks, software-defined networking (SDN) paradigm is introduced in the overlay networks to enable centralized and efficient routing of traffic in the overlay networks, thus, enabling better QoS. One of the main challenges in software-defined overlay networks is the fast-changing overlay link QoS characteristics. However, the existing routing algorithms for satisfying multiple QoS constraints in software-defined overlay networks involve high route computation time and thus these routing algorithms cannot adapt to the fast-changing overlay link QoS characteristics. Moreover, as we scale the size of overlay networks, the size of forwarding tables increases exponentially. This is because the existing routing schemes for ensuring multiple QoS constraints use both the source and the destination address for data-plane forwarding. This leads to pushing a huge amount of forwarding table entries by the controller through the network and thus limiting the size of the overlay network. We propose an efficient routing scheme, QROUTE, for satisfying multiple QoS constraints in software-defined overlay networks. QROUTE consists of a control plane routing algorithm which has significantly low route computation time because of employing a novel directed-acyclic-graph (DAG) based approach. QROUTE also reduces the forwarding entries in the data plane by using a QoS-metric-based forwarding scheme. We extensively evaluate QROUTE using traces from a global overlay service provider. We also examine QROUTE on a testbed of P4-BMv2 switches controlled by the ONOS controller using P4Runtime protocol. We find that QROUTE outperforms other state-of-the-art QoS routing schemes in route computation time, size of the forwarding tables and meeting the QoS requirements of various applications.

Homa: An Efficient Topology and Route Management Approach in SD-WAN Overlays

Abstract: This paper presents an efficient topology and route management approach in Software-Defined Wide Area Networks (SD-WAN). Traditional WANs suffer from low utilization and lack of global view of the network. Therefore, during failures, topology/service/traffic changes, or new policy requirements, the system does not always converge to the global optimal state. Using Software Defined Networking architectures in WANs provides the opportunity to design WANs with higher fault tolerance, scalability, and manageability. We exploit the correlation matrix derived from monitoring system between the virtual links to infer the underlying route topology and propose a route update approach that minimizes the total route update cost on all flows. We formulate the problem as an integer linear programming optimization problem and provide a centralized control approach that minimizes the total cost while satisfying the quality of service (QoS) on all flows. Experimental results on real network topologies demonstrate the effectiveness of the proposed approach in terms of disruption cost and average disrupted flows.

Survey on Algorithms for Self-stabilizing Overlay Networks

Abstract: The maintenance of efficient and robust overlay networks is one of the most fundamental and reoccurring themes in networking. This article presents a survey of state-of-the-art algorithms to design and repair overlay networks in a distributed manner. In particular, we discuss basic algorithmic primitives to preserve connectivity, review algorithms for the fundamental problem of graph linearization, and then survey self-stabilizing algorithms for metric and scalable topologies. We also identify open problems and avenues for future research.

Next level peer-to-peer overlay networks under high churns: a survey

Abstract: Peer-to-Peer (P2P) technology has seen a remarkable progress due to its decentralized and distributed approach. A wide range of applications such as social networking, file sharing, long range interpersonal communication etc. are carried out with ease by employing P2P protocol candidates. There exists a huge span of such P2P protocols. In this paper, we review advanced protocols like ZeroNet, Dat, Ares Galaxy, Accordion etc. evolved from classic peer-to-peer (P2P) overlay networks. We utilize term classic to allude protocols like Chord, Pastry, Tapestry, Kademlia, BitTorrent, Gnutella, Gia, NICE etc. While coming to their design, several challenges existed with classic approach under high churn environment with growing network communication rate. To address these multifaceted network issues with classic P2P systems, novel approaches evolved which helped researchers to built new application layer networks on existing P2P networks. We contribute in this paper by systematically characterizing next-level P2P (NL P2P) and examining their key concepts. Arrangement of distributed networks is completed by numerous analysts, which incorporates classic P2P systems. In this work, we therefore aim to make a further stride by deliberately talking about protocols created from classic P2P systems, and their performance comparison in dynamically changing environment. Different aspects of P2P overlay frameworks like routing, security, query, adaptation to non-critical failure and so forth dependent on developed conventions are additionally examined. Further, based on our review and study we put forward some of the exploring challenges with NL P2P frameworks.

Shortest paths in a hybrid network model

Abstract: We introduce a communication model for hybrid networks, where nodes have access to two different communication modes: a local mode where (like in traditional networks) communication is only possible between specific pairs of nodes, and a global mode where (like in overlay networks) communication between any pair of nodes is possible. Typically, communication over short-range connections is cheaper and can be done at a much higher rate than communication via the overlay network. Therefore, we are focusing on the LOCAL model for the local connections where nodes can exchange an unbounded amount of information per round. For the global communication we assume the so-called node-capacitated clique model, where in each round every node can exchange O(log n)-bit messages with O(log n) arbitrary nodes. We explore the impact of hybrid communication on the complexity of distributed algorithms by studying the problem of computing shortest paths in the graph given by the local connections. We present the following results. For the all-pairs shortest paths problem, we show that an exact solution can be computed in time O(n2/3) and that approximate solutions can be computed in time [MATH HERE] but not faster. For the single-source shortest paths problem an exact solution can be computed in time [MATH HERE], where SPD denotes the shortest path diameter. Furthermore, a (1 + o(1))-approximate solution can be computed in time O(n1/3). Finally, we show that for every constant e > 0, it is possible to compute an O(1)-approximate solution in time O(ne).

VTrace: Automatic Diagnostic System for Persistent Packet Loss in Cloud-Scale Overlay Network

Abstract: Persistent packet loss in the cloud-scale overlay network severely compromises tenant experiences. Cloud providers are keen to automatically and quickly determine the root cause of such problems. However, existing work is either designed for the physical network or insufficient to present the concrete reason of packet loss. In this paper, we propose to record and analyze the on-site forwarding condition of packets during packet-level tracing. The cloud-scale overlay network presents great challenges to achieve this goal with its high network complexity, multi-tenant nature, and diversity of root causes. To address these challenges, we present VTrace, an automatic diagnostic system for persistent packet loss over the cloud-scale overlay network. Utilizing the "fast path-slow path" structure of virtual forwarding devices (VFDs), e.g., vSwitches, VTrace installs several "coloring, matching and logging" rules in VFDs to selectively track the packets of interest and inspect them in depth. The detailed forwarding situation at each hop is logged and then assembled to perform analysis with an efficient path reconstruction scheme. Experiments are conducted to demonstrate VTrace's low overhead and quick responsiveness. We share experiences of how VTrace efficiently resolves persistent packet loss issues after deploying it in Alibaba Cloud for over 20 months.

A Reference Model and Prototype Implementation for SDN-Based Multi Layer Routing in Fog Environments

Abstract: If compared with Cloud computing, Fog computing is proving to support challenging scenarios imposing strict delay requirements, e.g., tactile Internet and Industrial Internet of Things (IIoT), and increased flexibility, e.g., dynamic Smart City and users’ follow-me provisioning case. In fact, by exploiting computing, storage, and connectivity resources in the proximity of sensors and actuators (for IIoT) and of mobile nodes carried by citizens (for Smart Cities), significant portions of services and functionalities can be migrated outside datacenters. However, such scenarios are characterized by increased heterogeneity of nodes in terms of hardware/software, of time-varying applications possibly offered by multiple service providers at the same time, and frequent joining/leaving of nodes as a typical behavior. To overcome these issues, the paper originally proposes Multi-Layer Advanced Networking Environment (Multi-LANE), a Multi Layer Routing (MLR) solution based on Software Defined Networking (SDN) that specifically targets the emerging and promising Fog-based deployment environments. Multi-LANE dynamically selects and exploits (even at the same time) different routing strategies and mechanisms suitable for applications with heterogeneous features and requirements. Based on its centralized point of view, our Multi-LANE SDN controller determines the most suitable path and configures the proper MLR forwarding mechanism, ranging from traditional IP and sequence-based overlays to more articulated ones based on the inspection of payload content types and values. In addition to design/implementation insights and to the availability of the Multi-LANE prototype, this paper also provides the community with a significant contribution in terms of novel models for forwarding mechanisms specialized for Fog computing scenarios.

Intent-Based Slicing between Containers in SDN Overlay Network

Abstract: Container-based service orchestration is getting famous increasingly because of its ability to be deployed quickly and it is cheaper as well as more reliable when compared to virtual machines. Leveraging the container characteristic, deployment of 5G modules as a group of containers on different nodes is an excellent solution to construct a 5g system. In a 5G system, network slicing plays a vital role to isolate the on-demand services and the SDN based overlay network consisting of containers provides the platform which manages to slice the network using intent-based networking. As the number of containers in a deployment increases on hosts across the overlay network with the passage of time in the 5G network, therefore it is necessary to manage them with the tool in a straight way with high-level abstraction. In this paper, we present the deployment of an overlay network which consists of Kubernetes nodes and Open vSwitch. In this paper, we also present the intent-based slicing system using Software Defined Network controller and an Intent-Based Networking (IBN) Manager among the containers across the Kubernetes pods in an overlay network. 

Data Management for Context-Aware Computing.

Abstract: We envisage future context-aware applications will dynamically adapt their behaviors to various context data from sources in wide-area networks, such as the Internet. Facing the changing context and the sheer number of context sources, a data management system that supports effective source organization and efficient data lookup becomes crucial to the easy development of context-aware applications. In this paper, we propose the design of a new context data management system that is equipped with query processing capabilities. We encapsulate the context sources into physical spaces belonging to different context spaces and organize them as peers in semantic overlay networks. Initial evaluation results of an experimental system prototype demonstrate the effectiveness of our design

Distributed Caching Mechanism for Popular Services Distribution in Converged Overlay Networks

Abstract: With the proliferation of portable devices, the exponential growth of the global mobile traffic brings great challenges to the traditional communication networks and the traditional wireless communication technologies. In this context, converged networks and cache-based data offloading have drawn more and more attention based on the strong correlation of services. This paper proposes a novel popular services pushing and caching scheme by using converged overlay networks. The most popular services are pushed by terrestrial broadcasting networks. And they are cached in ${n}$ router-nodes with limited cache sizes. Each router-node only interconnects with its neighbor nodes. Users are served through the router’s WiFi link. If the services requested are cached in the routers, the user can be immediately responded; otherwise, the requests can be responded through the link from cellular stations to the router. In the proposed scheme, the cache size of the router, the maximum number of requests each router can serve, and the whole-time delay are limited. Three node-selecting and dynamic programming algorithms are adopted to maximize the equivalent throughput. Analytical and numerical results demonstrate that the proposed scheme is very effective.

Methods to optimize multicast routing in overlay networks

Abstract: The disclosure provides an approach for reducing multicast traffic within a network by optimizing placement of virtual machines within subnets and within hosts, and by optimizing mapping of overlay multicast groups to underlay multicast groups. In one embodiment, substantially all VMs of a multicast group are migrated to the same subnet of the network. Thereafter or independently, VMs in the same subnet are migrated to the same host, ideally to the subnet proxy endpoint of that subnet. In the same or in another embodiment, if multiple overlay groups map to the same underlay group, one or more of the overlay groups may be remapped to a separate underlay group to improve network performance.

Methods, systems, and computer readable media for providing mobile device connectivity

Abstract: Methods, systems, and computer readable media for providing mobile device connectivity are disclosed. A system includes a mobile gateway implemented on one or more processors. The mobile gateway includes an on-premises telecommunications network core configured for establishing mobile data sessions for mobile user devices and enabling communication between the mobile user devices through the on-premises telecommunications network core. The mobile gateway includes a software-defined wide-area network (SD-WAN) controller configured for establishing an SD-WAN overlay network for connecting the mobile user devices to an external telecommunications network.

Stealthy DGoS Attack: DeGrading of Service under the Watch of Network Tomography

Abstract: Network tomography is a powerful tool to monitor the internal state of a closed network that cannot be measured directly, with broad applications in the Internet, overlay networks, and all-optical networks. However, existing network tomography solutions all assume that the measurements are trust-worthy, leaving open how effective they are in an adversarial environment with possibly manipulated measurements. To understand the fundamental limit of network tomography in such a setting, we formulate and analyze a novel type of attack that aims at maximally degrading the performance of targeted paths without being localized by network tomography. By analyzing properties of the optimal attack, we formulate novel combinatorial optimizations to design the optimal attack strategy, which are then linked to well-known problems and approximation algorithms. Our evaluations on real topologies demonstrate the large damage of such attacks, signaling the need of new defenses.

Mapping the Interplanetary Filesystem

Abstract: The Interplanetary Filesystem (IPFS) is a distributed data storage service frequently used by blockchain applications and for sharing content in a censorship-resistant manner. Data is hosted by an open set of peers, pointers to which are distributed using a Kademlia-based distributed hash table (DHT). In this paper, we study the structure of the resulting overlay network, as it significantly influences the robustness and performance of IPFS. We monitor and systematically crawl IPFS’ DHT towards mapping the IPFS overlay network. Our measurements found an average of 44474 nodes at every given time. At least 52. 19% of these reside behind a NAT and are not reachable from the outside, suggesting that a large share of the network is operated by private individuals on an as-needed basis. Based on our measurements and our analysis of the IPFS code, we observe that IPFS bears similarities to unstructured overlay networks in terms of content retrieval mechanics and overlay topology. While such a structure has benefits for robustness and the resistance against Sybil attacks, it leaves room for improvement in terms of performance and query privacy.

DConstructor: Efficient and Robust Network Construction with Polylogarithmic Overhead

Abstract: With the rise of dynamic reconfigurable networks such as Peer-to-Peer (P2P) networks, overlay networks, ad hoc wireless and mesh networks, it has become important to construct and maintain topologies with various desirable properties (such as connectivity, low diameter, expansion, low degree etc.) in an efficient decentralized manner. The main result of this paper is a distributed protocol called DConstructor that given any (connected) network topology will "converge" to a given (desired) target topology such as an expander, hypercube, or Chord, with high probability. Our protocol is efficient, lightweight, and scalable, and it incurs only O(polylog(n)) overhead (where n is the network size) for topology construction and maintenance: only polylogarithmic (in n) bits need to be processed and sent by each node per round, the convergence time is polylogarithmic rounds and any node's computation cost per round is also polylogarithmic. Our protocol is robust and self-repairing in the sense that it will converge to the desired topology in polylogarithmic rounds and polylogarithmic communication cost under dynamic topology changes and arbitrary insertions and deletions of nodes.

Data-Driven Intelligence on Innovation and Competition: Patent Overlay Network Visualization and Analytics

Abstract: Technology positions of firms may determine their competitive advantages and innovation capabilities. While a tangible understanding of technology positions can inform competitive intelligence, the...

Techniques For Secure Blockchain Routing

Abstract: Described herein are systems and methods for providing secure blockchain routing utilizing an extended blockchain protocol. In some embodiments, a blockchain routing node may join an overlay network including a plurality of blockchain routing nodes. The blockchain routing node may receive a plurality of forwarding tables from the plurality of blockchain routing nodes in accordance with an extended blockchain protocol. The blockchain routing node may determine a routing table for the overlay network based at least on part on the plurality of forwarding tables. In some embodiments, the blockchain routing node may route a payload message to a destination blockchain routing node in the overlay network in accordance with the determined routing table.

Identification of Overlay Operations, Administration, and Maintenance (OAM)

Abstract: This document analyzes how the presence of Operations, Administration, and Maintenance (OAM) control command and/or special data is identified in some overlay networks and an impact on the choice of identification may have on OAM functionality.

Key Secrecy Performance Metrics of Overlay Networks with Energy Scavenging and Artificial Noise

Abstract: Main design objectives of future wireless networks are information security and efficient spectrum-and-energy utilization to serve a tremendous number of users and applications. This paper proposes overlay networks with energy scavenging and artificial noise to achieve these objectives concurrently. In these networks, unlicensed user assists and secures licensed transmission in reward for its access to licensed spectrum by relaying licensed information, producing artificial noise, and transmitting its private information. Key secrecy performance metrics of these networks such as secrecy outage probability, positive secrecy capacity probability, intercept probability, and secrecy throughput are represented in exact formulas, which are helpful in quickly assessing secrecy performances in important specifications as well as optimizing system design without computer simulations. Numerous results are provided to corroborate these formulas and have insightful understandings into secrecy capability of overlay networks with energy scavenging and artificial noise.

GCBlock: A Grouping and Coding Based Storage Scheme for Blockchain System

Abstract: To achieve the tamper-proof, reliability and traceability of transactions in a trustless environment, the blockchain requires each peer node to store the whole global ledger. However, as transactions keep increasing over time, the storage cost of each node increases. In addition, many schemes have been proposed to boost rapid transactions which will even lead transactions to grow explosively. The problem of storage is becoming one challenge of blockchain since the storage overhead of each node increase rapidly. Reducing the storage overhead of each participant is very urgent and worthy. In this paper, we present GCBlock: a grouping overlay network storage scheme for the blockchain which can reduce the storage overhead of nodes and cut the whole storage cost of the blockchain greatly while keeping the underlying protocols. In our scheme, we try to group the nodes according to their physical fuzzy distance to reduce the overall delay when tracing. We set rules of autonomous check to deal with evil behavior within the group. To further enhance the stability of our scheme, we propose the transcript fractional repetition code which is newly constructed based on the fractional repetition code to encode data. Finally, we make a comprehensive evaluation of GCBlock and the results show that it is workable and reasonable.

TOM: a self-trained Tomography solution for Overlay networks Monitoring

Abstract: Network tomography is a discipline that aims to infer the internal network characteristics from end-to-end correlated measurements performed at the network edge. This work presents a new tomography approach for link metrics inference in an SDN/NFV environment (even if it can be exported outside this field) that we called TOM (Tomography for Overlay networks Monitoring). In such an environment, we are particularly interested in supervising network slicing, a recent tool enabling to create multiple virtual networks for different applications and QoS constraints on a Telco infrastructure. The goal is to infer the underlay resources states from the measurements performed in the overlay structure. We model the inference task as a regression problem that we solve following a Neural Network approach. Since getting labeled data for the training phase can be costly, our procedure generates artificial data for the training phase. By creating a large set of random training examples, the Neural Network learns the relations between the measures done at path and link levels. This approach takes advantage of efficient Machine Learning solutions to solve a classic inference problem. Simulations with a public dataset show very promising results compared to statistical-based methods. We explored mainly additive metrics such as delays or logs of loss rates, but the approach can also be used for non-additive ones such as bandwidth.