bluuebunny/crossref_metadata_2025 huggingface dataset:
Maximizing the Number of Good Dies for Streaming Applications in NoC-Based MPSoCs Under Process Variation
Authors: Mirzoyan Davit , Akesson Benny , Stuijk Sander , Goossens Kees
Published: September 2015

Scaling CMOS technology into nanometer feature-size nodes has made it practically impossible to precisely control the manufacturing process. This results in variation in the speed and power consumption of a circuit. As a solution to process-induced variations, circuits are conventionally implemented with conservative design margins to guarantee the target frequency of each hardware component in manufactured multiprocessor chips. This approach, referred to as worst-case design, results in a considerable circuit upsizing, in turn reducing the number of dies on a wafer.

This work deals with the design of real-time systems for streaming applications (e.g., video decoders) constrained by a throughput requirement (e.g., frames per second) with reduced design margins, referred to as
better-than-worst-case design
. To this end, the first contribution of this work is
a complete modeling framework that captures a streaming application mapped to an NoC-based multiprocessor system with voltage-frequency islands under process-induced die-to-die and within-die frequency variations
. The framework is used to analyze the impact of variations in the frequency of hardware components on
application throughput at the system level
. The second contribution of this work is
a methodology to use the proposed framework and estimate the impact of reducing circuit design margins on the number of good dies that satisfy the throughput requirement of a real-time streaming application
. We show on both synthetic and real applications that the proposed better-than-worst-case design approach can increase the number of good dies by up to 9.6% and 18.8% for designs with and without fixed SRAM and IO blocks, respectively.
Lifetime Reliability Enhancement of Microprocessors
Authors: Hong Hyejeong , Lim Jaeil , Lim Hyunyul , Kang Sungho
Published: September 2015

Ensuring lifetime reliability of microprocessors has become more critical. Continuous scaling and increasing temperatures due to growing power density are threatening lifetime reliability. Negative bias temperature instability (NBTI) has been known for decades, but its impact has been insignificant compared to other factors. Aggressive scaling, however, makes NBTI the most serious threat to chip lifetime reliability in today's and future process technologies. The delay of microprocessors gradually increases as time goes by, due to stress and recovery phases. The delay eventually becomes higher than the value required to meet design constraints, which results in failed systems. In this article, the mechanism of NBTI and its effects on lifetime reliability are presented, then various techniques to mitigate NBTI degradation on microprocessors are introduced. The mitigation can be addressed at either the circuit level or architectural level. Circuit-level techniques include design-time techniques such as transistor sizing and NBTI-aware synthesis. Forward body biasing, and adaptive voltage scaling are adaptive techniques that can mitigate NBTI degradation at the circuit level by controlling the threshold voltage or supply voltage to hide the lengthened delay caused by NBTI degradation. Reliability has been regarded as something to be addressed by chip manufacturers. However, there are recent attempts to bring lifetime reliability problems to the architectural level. Architectural techniques can reduce the cost added by circuit-level techniques, which are based on the worst-case degradation estimation. Traditional low-power and thermal management techniques can be successfully extended to deal with reliability problems since aging is dependent on power consumption and temperature. Self-repair is another option to enhance the lifetime of microprocessors using either core-level or lower-level redundancy. With a growing thermal crisis and constant scaling, lifetime reliability requires more intensive research in conjunction with other design issues.
Crash consistency
Authors: Pillai T. S. , Chidambaram V. , Alagappan R. , Al-Kiswany S. , Arpaci-Dusseau A. C. , Arpaci-Dusseau R. H.
Published: September 2015

Rethinking the fundamental abstractions of the file system.
Deterministic Replay
Authors: Chen Yunji , Zhang Shijin , Guo Qi , Li Ling , Wu Ruiyang , Chen Tianshi
Published: September 2015

Deterministic replay is a type of emerging technique dedicated to providing deterministic executions of computer programs in the presence of nondeterministic factors. The application scopes of deterministic replay are very broad, making it an important research topic in domains such as computer architecture, operating systems, parallel computing, distributed computing, programming languages, verification, and hardware testing.

In this survey, we comprehensively review existing studies on deterministic replay by introducing a taxonomy. Basically, existing deterministic replay schemes can be classified into two categories,
single-processor
(SP) schemes and
multiprocessor
(MP) schemes. By reviewing the details of these two categories of schemes respectively, we summarize and compare how existing schemes address technical issues such as log size, record slowdown, replay slowdown, implementation cost, and probe effect, which may shed some light on future studies on deterministic replay.
Systems of Systems Engineering
Authors: Nielsen Claus Ballegaard , Larsen Peter Gorm , Fitzgerald John , Woodcock Jim , Peleska Jan
Published: September 2015

The term “System of Systems” (SoS) has been used since the 1950s to describe systems that are composed of independent constituent systems, which act jointly towards a common goal through the synergism between them. Examples of SoS arise in areas such as power grid technology, transport, production, and military enterprises. SoS engineering is challenged by the independence, heterogeneity, evolution, and emergence properties found in SoS. This article focuses on the role of model-based techniques within the SoS engineering field. A review of existing attempts to define and classify SoS is used to identify several dimensions that characterise SoS applications. The SoS field is exemplified by a series of representative systems selected from the literature on SoS applications. Within the area of model-based techniques the survey specifically reviews the state of the art for SoS modelling, architectural description, simulation, verification, and testing. Finally, the identified dimensions of SoS characteristics are used to identify research challenges and future research areas of model-based SoS engineering.
The Multiple Facets of Software Diversity
Authors: Baudry Benoit , Monperrus Martin
Published: September 2015

Early experiments with software diversity in the mid 1970s investigated N-version programming and recovery blocks to increase the reliability of embedded systems. Four decades later, the literature about software diversity has expanded in multiple directions: goals (fault tolerance, security, software engineering), means (managed or automated diversity), and analytical studies (quantification of diversity and its impact). Our article contributes to the field of software diversity as the first work that adopts an inclusive vision of the area, with an emphasis on the most recent advances in the field. This survey includes classical work about design and data diversity for fault tolerance, as well as the cybersecurity literature that investigates randomization at different system levels. It broadens this standard scope of diversity to include the study and exploitation of natural diversity and the management of diverse software products. Our survey includes the most recent works, with an emphasis from 2000 to the present. The targeted audience is researchers and practitioners in one of the surveyed fields who miss the big picture of software diversity. Assembling the multiple facets of this fascinating topic sheds a new light on the field.
Deterring Cheating in Online Environments
Authors: Corrigan-Gibbs Henry , Gupta Nakull , Northcutt Curtis , Cutrell Edward , Thies William
Published: September 2015

Many Internet services depend on the integrity of their users, even when these users have strong incentives to behave dishonestly. Drawing on experiments in two different online contexts, this study measures the prevalence of cheating and evaluates two different methods for deterring it. Our first experiment investigates cheating behavior in a pair of online exams spanning 632 students in India. Our second experiment examines dishonest behavior on Mechanical Turk through an online task with 2,378 total participants. Using direct measurements that are not dependent on self-reports, we detect significant rates of cheating in both environments. We confirm that honor codes--despite frequent use in massive open online courses (MOOCs)--lead to only a small and insignificant reduction in online cheating behaviors. To overcome these challenges, we propose a new intervention: a stern warning that spells out the potential consequences of cheating. We show that the warning leads to a significant (about twofold) reduction in cheating, consistent across experiments. We also characterize the demographic correlates of cheating on Mechanical Turk. Our findings advance the understanding of cheating in online environments, and suggest that replacing traditional honor codes with warnings could be a simple and effective way to deter cheating in online courses and online labor marketplaces.
Action-Transferred Navigation Technique Design Approach Supporting Human Spatial Learning
Authors: Kim Ji-Sun , Gračanin Denis , Yang Taeyoung , Quek Francis
Published: September 2015

We propose a new action-transferred design approach by which the benefits of embodied cognition and activity can be realized to enhance spatial learning and usability for navigating virtual spaces. The action-transferred design approach is supported by theories of learning, action-perception, and neuropsychology. These theories help us understand how human action can be transferred to different body parts for improving the usability of interaction techniques and why the acquired spatial knowledge using the transferred action may remain the same independent of the used body parts. The finger-walking-in-place (FWIP) navigation technique is used as a design example to demonstrate the concept of the action-transferred design approach. Leveraging 3D immersive virtual reality technology, we performed an empirical study to evaluate the performance of the action-transferred FWIP navigation technique in terms of spatial knowledge acquisition. The FWIP navigation technique was compared with a full-body-based walking-like (sensor-fusion walking-in-place; SF-WIP) navigation technique and a well-known, convenient (Joystick) navigation technique using a common input device, that is, a wand with a joystick. Both the action-transferred and the full-body-based navigation techniques were more effective for spatial learning than the navigation technique using the common input device. However, only the action-transferred FWIP navigation technique can provide users with the convenience of navigating with their fingers. These results suggest that the action-transferred design approach is useful in designing a navigation technique supporting users' spatial learning performance more effectively and conveniently. Possible design implications for broader applications are discussed and indicate that the action-transferred design approach is worth further study.
Automotive systems get smarter
Authors: Greengard Samuel
Published: September 2015

Automotive infotainment systems are driving changes to automobiles, and to driver behavior.
Cyber policies on the rise
Authors: Kirkpatrick Keith
Published: September 2015

A growing number of companies are taking out cybersecurity insurance policies to protect themselves from the costs of data breaches.
Computing numerically with functions instead of numbers
Authors: Trefethen Lloyd N.
Published: September 2015

Science and engineering depend upon computation of functions such as flow fields, charge distributions, and quantum states. Ultimately, such computations require some kind of discretization, but in recent years, it has become possible in many cases to hide the discretizations from the user. We present the Chebfun system for numerical computation with functions, which is based on a key idea: an analogy of floating-point arithmetic for functions rather than numbers.
Formalization of Weak Emergence in Multiagent Systems
Authors: Szabo Claudia , Teo Yong Meng
Published: September 2015

Emergence becomes a distinguishing system feature as system complexity grows with the number of components, interactions, and connectivities. Examples of emergent behaviors include the flocking of birds, traffic jams, and hubs in social networks, among others. Despite significant research interest in recent years, there is a lack of formal methods to understand, identify, and predict emergent behavior in multiagent systems. Existing approaches either require detailed prior knowledge about emergent behavior or are computationally infeasible. This article introduces a grammar-based approach to formalize and identify the existence and extent of emergence without the need for prior knowledge of emergent properties. Our approach is based on weak (basic) emergence that is both generated and autonomous from the underlying agents. We employ formal grammars to capture agent interactions in the forms of words written on a common tape. Our formalism captures agents of diverse types and open systems. We propose an automated approach for the identification of emergent behavior and show its benefits through theoretical and experimental analysis. We also propose a significant reduction of state-space explosion through the use of our proposed degree of interaction metrics. Our experiments using the boids model show the feasibility of our approach but also highlight future avenues of improvement.
Future Tense: Processional
Authors: Bainbridge William Sims
Published: September 2015

From the intersection of computational science and technological speculation, with boundaries limited only by our ability to imagine what could be. Information processing gives spiritual meaning to life, for those who make it their life's work.
Discovering genes involved in disease and the mystery of missing heritability
Authors: Eskin Eleazar
Published: September 2015

The challenge of missing heritability offers great contribution options for computer scientists.
Condor
Authors: Schlinker Brandon , Mysore Radhika Niranjan , Smith Sean , Mogul Jeffrey C. , Vahdat Amin , Yu Minlan , Katz-Bassett Ethan , Rubin Michael
Published: September 2015

The design space for large, multipath datacenter networks is large and complex, and no one design fits all purposes. Network architects must trade off many criteria to design cost-effective, reliable, and maintainable networks, and typically cannot explore much of the design space. We present Condor, our approach to enabling a rapid, efficient design cycle. Condor allows architects to express their requirements as constraints via a Topology Description Language (TDL), rather than having to directly specify network structures. Condor then uses constraint-based synthesis to rapidly generate candidate topologies, which can be analyzed against multiple criteria. We show that TDL supports concise descriptions of topologies such as fat-trees, BCube, and DCell; that we can generate known and novel variants of fat-trees with simple changes to a TDL file; and that we can synthesize large topologies in tens of seconds. We also show that Condor supports the daunting task of designing multi-phase network expansions that can be carried out on live networks.
Laissez-Faire
Authors: Hu Pan , Zhang Pengyu , Ganesan Deepak
Published: September 2015

Backscatter provides dual-benefits of energy harvesting and low-power communication, making it attractive to a broad class of wireless sensors. But the design of a protocol that enables extremely power-efficient radios for harvesting-based sensors as well as high-rate data transfer for data-rich sensors presents a conundrum. In this paper, we present a new {\em fully asymmetric} backscatter communication protocol where nodes blindly transmit data as and when they sense. This model enables fully flexible node designs, from extraordinarily power-efficient backscatter radios that consume barely a few micro-watts to high-throughput radios that can stream at hundreds of Kbps while consuming a paltry tens of micro-watts. The challenge, however, lies in decoding concurrent streams at the reader, which we achieve using a novel combination of time-domain separation of interleaved signal edges, and phase-domain separation of colliding transmissions. We provide an implementation of our protocol, LF-Backscatter, and show that it can achieve an order of magnitude or more improvement in throughput, latency and power over state-of-art alternatives.
BwE
Authors: Kumar Alok , Jain Sushant , Naik Uday , Raghuraman Anand , Kasinadhuni Nikhil , Zermeno Enrique Cauich , Gunn C. Stephen , Ai Jing , Carlin Björn , Amarandei-Stavila Mihai , Robin Mathieu , Siganporia Aspi , Stuart Stephen , Vahdat Amin
Published: September 2015

WAN bandwidth remains a constrained resource that is economically infeasible to substantially overprovision. Hence, it is important to allocate capacity according to service priority and based on the incremental value of additional allocation. For example, it may be the highest priority for one service to receive 10Gb/s of bandwidth but upon reaching such an allocation, incremental priority may drop sharply favoring allocation to other services. Motivated by the observation that individual flows with fixed priority may not be the ideal basis for bandwidth allocation, we present the design and implementation of Bandwidth Enforcer (BwE), a global, hierarchical bandwidth allocation infrastructure. BwE supports: i) service-level bandwidth allocation following prioritized bandwidth functions where a service can represent an arbitrary collection of flows, ii)independent allocation and delegation policies according to user-defined hierarchy, all accounting for a global view of bandwidth and failure conditions, iii) multi-path forwarding common in traffic-engineered networks, and iv) a central administrative point to override (perhaps faulty) policy during exceptional conditions. BwE has delivered more service efficient bandwidth utilization and simpler management in production for multiple years.
Multi-Context TLS (mcTLS)
Authors: Naylor David , Schomp Kyle , Varvello Matteo , Leontiadis Ilias , Blackburn Jeremy , López Diego R. , Papagiannaki Konstantina , Rodriguez Rodriguez Pablo , Steenkiste Peter
Published: September 2015

A significant fraction of Internet traffic is now encrypted and HTTPS will likely be the default in HTTP/2. However, Transport Layer Security (TLS), the standard protocol for encryption in the Internet, assumes that all functionality resides at the endpoints, making it impossible to use in-network services that optimize network resource usage, improve user experience, and protect clients and servers from security threats. Re-introducing in-network functionality into TLS sessions today is done through hacks, often weakening overall security.

In this paper we introduce multi-context TLS (mcTLS), which extends TLS to support middleboxes. mcTLS breaks the current "all-or-nothing" security model by allowing endpoints and content providers to explicitly introduce middleboxes in secure end-to-end sessions while controlling which parts of the data they can read or write.

We evaluate a prototype mcTLS implementation in both controlled and "live" experiments, showing that its benefits come at the cost of minimal overhead. More importantly, we show that mcTLS can be incrementally deployed and requires only small changes to client, server, and middlebox software.
Packet-Level Telemetry in Large Datacenter Networks
Authors: Zhu Yibo , Kang Nanxi , Cao Jiaxin , Greenberg Albert , Lu Guohan , Mahajan Ratul , Maltz Dave , Yuan Lihua , Zhang Ming , Zhao Ben Y. , Zheng Haitao
Published: September 2015

Debugging faults in complex networks often requires capturing and analyzing traffic at the packet level. In this task, datacenter networks (DCNs) present unique challenges with their scale, traffic volume, and diversity of faults. To troubleshoot faults in a timely manner, DCN administrators must a) identify affected packets inside large volume of traffic; b) track them across multiple network components; c) analyze traffic traces for fault patterns; and d) test or confirm potential causes. To our knowledge, no tool today can achieve both the specificity and scale required for this task.

We present Everflow, a packet-level network telemetry system for large DCNs. Everflow traces specific packets by implementing a powerful packet filter on top of "match and mirror" functionality of commodity switches. It shuffles captured packets to multiple analysis servers using load balancers built on switch ASICs, and it sends "guided probes" to test or confirm potential faults. We present experiments that demonstrate Everflow's scalability, and share experiences of troubleshooting network faults gathered from running it for over 6 months in Microsoft's DCNs.
A Control-Theoretic Approach for Dynamic Adaptive Video Streaming over HTTP
Authors: Yin Xiaoqi , Jindal Abhishek , Sekar Vyas , Sinopoli Bruno
Published: September 2015

User-perceived quality-of-experience (QoE) is critical in Internet video applications as it impacts revenues for content providers and delivery systems. Given that there is little support in the network for optimizing such measures, bottlenecks could occur anywhere in the delivery system. Consequently, a robust bitrate adaptation algorithm in client-side players is critical to ensure good user experience. Previous studies have shown key limitations of state-of-art commercial solutions and proposed a range of heuristic fixes. Despite the emergence of several proposals, there is still a distinct lack of consensus on: (1) How best to design this client-side bitrate adaptation logic (e.g., use rate estimates vs. buffer occupancy); (2) How well specific classes of approaches will perform under diverse operating regimes (e.g., high throughput variability); or (3) How do they actually balance different QoE objectives (e.g., startup delay vs. rebuffering). To this end, this paper makes three key technical contributions. First, to bring some rigor to this space, we develop a principled control-theoretic model to reason about a broad spectrum of strategies. Second, we propose a novel model predictive control algorithm that can optimally combine throughput and buffer occupancy information to outperform traditional approaches. Third, we present a practical implementation in a reference video player to validate our approach using realistic trace-driven emulations.
Large-scale Measurements of Wireless Network Behavior
Authors: Biswas Sanjit , Bicket John , Wong Edmund , Musaloiu-E Raluca , Bhartia Apurv , Aguayo Dan
Published: September 2015

Meraki is a cloud-based network management system which provides centralized configuration, monitoring, and network troubleshooting tools across hundreds of thousands of sites worldwide. As part of its architecture, the Meraki system has built a database of time-series measurements of wireless link, client, and application behavior for monitoring and debugging purposes. This paper studies an anonymized subset of measurements, containing data from approximately ten thousand radio access points, tens of thousands of links, and 5.6 million clients from one-week periods in January 2014 and January 2015 to provide a deeper understanding of real-world network behavior. This paper observes the following phenomena: wireless network usage continues to grow quickly, driven most by growth in the number of devices connecting to each network. Intermediate link delivery rates are common indoors across a wide range of deployment environments. Typical access points share spectrum with dozens of nearby networks, but the presence of a network on a channel does not predict channel utilization. Most access points see 2.4 GHz channel utilization of 20% or more, with the top decile seeing greater than 50%, and the majority of the channel use contains decodable 802.11 headers.
Herd
Authors: Le Blond Stevens , Choffnes David , Caldwell William , Druschel Peter , Merritt Nicholas
Published: September 2015

Effectively anonymizing Voice-over-IP (VoIP) calls requires a scalable anonymity network that is resilient to traffic analysis and has sufficiently low delay for high-quality voice calls. The popular Tor anonymity network, for instance, is not designed for the former and cannot typically achieve the latter. In this paper, we present the design, implementation, and experimental evaluation of Herd, an anonymity network where a set of dedicated, fully interconnected cloud-based proxies yield suitably low-delay circuits, while untrusted superpeers add scalability. Herd provides caller/callee anonymity among the clients within a trust zone (e.g., jurisdiction) and under a strong adversarial model. Simulations based on a trace of 370 million mobile phone calls among 10.8 million users indicate that Herd achieves anonymity among millions of clients with low bandwidth requirements, and that superpeers decrease the bandwidth and CPU requirements of the trusted infrastructure by an order of magnitude. Finally, experiments using a prototype deployment on Amazon EC2 show that Herd has a delay low enough for high-quality calls in most cases.
Central Control Over Distributed Routing
Authors: Vissicchio Stefano , Tilmans Olivier , Vanbever Laurent , Rexford Jennifer
Published: September 2015

Centralizing routing decisions offers tremendous flexibility, but sacrifices the robustness of distributed protocols. In this paper, we present Fibbing, an architecture that achieves both flexibility and robustness through central control over distributed routing. Fibbing introduces fake nodes and links into an underlying link-state routing protocol, so that routers compute their own forwarding tables based on the augmented topology. Fibbing is expressive, and readily supports flexible load balancing, traffic engineering, and backup routes. Based on high-level forwarding requirements, the Fibbing controller computes a compact augmented topology and injects the fake components through standard routing-protocol messages. Fibbing works with any unmodified routers speaking OSPF. Our experiments also show that it can scale to large networks with many forwarding requirements, introduces minimal overhead, and quickly reacts to network and controller failures.
Adaptive Congestion Control for Unpredictable Cellular Networks
Authors: Zaki Yasir , Pötsch Thomas , Chen Jay , Subramanian Lakshminarayanan , Görg Carmelita
Published: September 2015

Legacy congestion controls including TCP and its variants are known to perform poorly over cellular networks due to highly variable capacities over short time scales, self-inflicted packet delays, and packet losses unrelated to congestion. To cope with these challenges, we present Verus, an end-to-end congestion control protocol that uses delay measurements to react quickly to the capacity changes in cellular networks without explicitly attempting to predict the cellular channel dynamics. The key idea of Verus is to continuously learn a delay profile that captures the relationship between end-to-end packet delay and outstanding window size over short epochs and uses this relationship to increment or decrement the window size based on the observed short-term packet delay variations. While the delay-based control is primarily for congestion avoidance, Verus uses standard TCP features including multiplicative decrease upon packet loss and slow start. Through a combination of simulations, empirical evaluations using cellular network traces, and real-world evaluations against standard TCP flavors and state of the art protocols like Sprout, we show that Verus outperforms these protocols in cellular channels. In comparison to TCP Cubic, Verus achieves an order of magnitude (> 10x) reduction in delay over 3G and LTE networks while achieving comparable throughput (sometimes marginally higher). In comparison to Sprout, Verus achieves up to 30% higher throughput in rapidly changing cellular networks.
BlindBox
Authors: Sherry Justine , Lan Chang , Popa Raluca Ada , Ratnasamy Sylvia
Published: September 2015

Many network middleboxes perform deep packet inspection (DPI), a set of useful tasks which examine packet payloads. These tasks include intrusion detection (IDS), exfiltration detection, and parental filtering. However, a long-standing issue is that once packets are sent over HTTPS, middleboxes can no longer accomplish their tasks because the payloads are encrypted. Hence, one is faced with the choice of only one of two desirable properties: the functionality of middleboxes and the privacy of encryption. We propose BlindBox, the first system that simultaneously provides {\em both} of these properties. The approach of BlindBox is to perform the deep-packet inspection {\em directly on the encrypted traffic. BlindBox realizes this approach through a new protocol and new encryption schemes.

We demonstrate that BlindBox enables applications such as IDS, exfiltration detection and parental filtering, and supports real rulesets from both open-source and industrial DPI systems. We implemented BlindBox and showed that it is practical for settings with long-lived HTTPS connections. Moreover, its core encryption scheme is 3-6 orders of magnitude faster than existing relevant cryptographic schemes.
Caraoke
Authors: Abari Omid , Vasisht Deepak , Katabi Dina , Chandrakasan Anantha
Published: September 2015

Electronic toll collection transponders, e.g., E-ZPass, are a widely-used wireless technology. About 70% to 89% of the cars in US have these devices, and some states plan to make them mandatory. As wireless devices however, they lack a basic function: a MAC protocol that prevents collisions. Hence, today, they can be queried only with directional antennas in isolated spots. However, if one could interact with e-toll transponders anywhere in the city despite collisions, it would enable many smart applications. For example, the city can query the transponders to estimate the vehicle flow at every intersection. It can also localize the cars using their wireless signals, and detect those that run a red-light. The same infrastructure can also deliver smart street-parking, where a user parks anywhere on the street, the city localizes his car, and automatically charges his account. This paper presents Caraoke, a networked system for delivering smart services using e-toll transponders. Our design operates with existing unmodified transponders, allowing for applications that communicate with, localize, and count transponders, despite wireless collisions. To do so, Caraoke exploits the structure of the transponders' signal and its properties in the frequency domain. We built Caraoke reader into a small PCB that harvests solar energy and can be easily deployed on street lamps. We also evaluated Caraoke on four streets on our campus and demonstrated its capabilities.
PGA
Authors: Prakash Chaithan , Lee Jeongkeun , Turner Yoshio , Kang Joon-Myung , Akella Aditya , Banerjee Sujata , Clark Charles , Ma Yadi , Sharma Puneet , Zhang Ying
Published: September 2015

Software Defined Networking (SDN) and cloud automation enable a large number of diverse parties (network operators, application admins, tenants/end-users) and control programs (SDN Apps, network services) to generate network policies independently and dynamically. Yet existing policy abstractions and frameworks do not support natural expression and automatic composition of high-level policies from diverse sources. We tackle the open problem of automatic, correct and fast composition of multiple independently specified network policies. We first develop a high-level Policy Graph Abstraction (PGA) that allows network policies to be expressed simply and independently, and leverage the graph structure to detect and resolve policy conflicts efficiently. Besides supporting ACL policies, PGA also models and composes service chaining policies, i.e., the sequence of middleboxes to be traversed, by merging multiple service chain requirements into conflict-free composed chains. Our system validation using a large enterprise network policy dataset demonstrates practical composition times even for very large inputs, with only sub-millisecond runtime latencies.
Presto
Authors: He Keqiang , Rozner Eric , Agarwal Kanak , Felter Wes , Carter John , Akella Aditya
Published: September 2015

Datacenter networks deal with a variety of workloads, ranging from latency-sensitive small flows to bandwidth-hungry large flows. Load balancing schemes based on flow hashing, e.g., ECMP, cause congestion when hash collisions occur and can perform poorly in asymmetric topologies. Recent proposals to load balance the network require centralized traffic engineering, multipath-aware transport, or expensive specialized hardware. We propose a mechanism that avoids these limitations by (i) pushing load-balancing functionality into the soft network edge (e.g., virtual switches) such that no changes are required in the transport layer, customer VMs, or networking hardware, and (ii) load balancing on fine-grained, near-uniform units of data (flowcells) that fit within end-host segment offload optimizations used to support fast networking speeds. We design and implement such a soft-edge load balancing scheme, called Presto, and evaluate it on a 10 Gbps physical testbed. We demonstrate the computational impact of packet reordering on receivers and propose a mechanism to handle reordering in the TCP receive offload functionality. Presto's performance closely tracks that of a single, non-blocking switch over many workloads and is adaptive to failures and topology asymmetry.
Alibi Routing
Authors: Levin Dave , Lee Youndo , Valenta Luke , Li Zhihao , Lai Victoria , Lumezanu Cristian , Spring Neil , Bhattacharjee Bobby
Published: September 2015

There are several mechanisms by which users can gain insight into where their packets have gone, but no mechanisms allow users undeniable proof that their packets did not traverse certain parts of the world while on their way to or from another host. This paper introduces the problem of finding "proofs of avoidance": evidence that the paths taken by a packet and its response avoided a user-specified set of "forbidden" geographic regions. Proving that something did not happen is often intractable, but we demonstrate a low-overhead proof structure built around the idea of what we call "alibis": relays with particular timing constraints that, when upheld, would make it impossible to traverse both the relay and the forbidden regions.

We present Alibi Routing, a peer-to-peer overlay routing system for finding alibis securely and efficiently. One of the primary distinguishing characteristics of Alibi Routing is that it does not require knowledge of--or modifications to--the Internet's routing hardware or policies. Rather, Alibi Routing is able to derive its proofs of avoidance from user-provided GPS coordinates and speed of light propagation delays. Using a PlanetLab deployment and larger-scale simulations, we evaluate Alibi Routing to demonstrate that many source-destination pairs can avoid countries of their choosing with little latency inflation. We also identify when Alibi Routing does not work: it has difficulty avoiding regions that users are very close to (or, of course, inside of).
The Internet of Names
Authors: van Rijswijk-Deij Roland , Jonker Mattijs , Sperotto Anna , Pras Aiko
Published: September 2015

The Domain Name System (DNS) is part of the core infrastructure of the Internet. Tracking changes in the DNS over time provides valuable information about the evolution of the Internet's infrastructure. Until now, only one large-scale approach to perform these kinds of measurements existed, passive DNS (pDNS). While pDNS is useful for applications like tracing security incidents, it does not provide sufficient information to reliably track DNS changes over time. We use a complementary approach based on active measurements, which provides a unique, comprehensive dataset on the evolution of DNS over time. Our high-performance infrastructure performs Internet-scale active measurements, currently querying over 50% of the DNS name space on a daily basis. Our infrastructure is designed from the ground up to enable big data analysis approaches on, e.g., a Hadoop cluster. With this novel approach we aim for a quantum leap in DNS-based measurement and analysis of the Internet.
Toward Automated Testing of Geo-Distributed Replica Selection Algorithms
Authors: Bogdanov Kirill , Peón-Quirós Miguel , Maguire Gerald Q. , Kostić Dejan
Published: September 2015

Many geo-distributed systems rely on a replica selection algorithms to communicate with the closest set of replicas. Unfortunately, the bursty nature of the Internet traffic and ever changing network conditions present a problem in identifying the best choices of replicas. Suboptimal replica choices result in increased response latency and reduced system performance. In this work we present GeoPerf, a tool that tries to automate testing of geo-distributed replica selection algorithms. We used GeoPerf to test Cassandra and MongoDB, two popular data stores, and found bugs in each of these systems.
Federated End-to-End Authentication for the Constrained Internet of Things Using IBC and ECC
Authors: Markmann Tobias , Schmidt Thomas C. , Wählisch Matthias
Published: September 2015

Authentication of smart objects is a major challenge for the Internet of Things (IoT), and has been left open in DTLS. Leveraging locally managed IPv6 addresses with identity-based cryptography (IBC), we propose an efficient end-to-end authentication that (a) assigns a robust and deployment-friendly federation scheme to gateways of IoT subnetworks, and (b) has been evaluated with a modern twisted Edwards elliptic curve cryptography (ECC). Our early results demonstrate feasibility and promise efficiency after ongoing optimizations.
EPOXIDE
Authors: Lévai Tamás , Pelle István , Németh Felicián , Gulyás András
Published: September 2015

SDN opens a new chapter in network troubleshooting as besides misconfigurations and firmware/hardware errors, software bugs can occur all over the SDN stack. As an answer to this challenge the networking community developed a wealth of piecemeal SDN troubleshooting tools aiming to track down misconfigurations or bugs of a specific nature (e.g. in a given SDN layer). In this demonstration we present EPOXIDE, an Emacs based modular framework, which can effectively combine existing network and software troubleshooting tools in a single platform and defines a possible way of integrated SDN troubleshooting.
WiMAC
Authors: Yau Simon , Ge Liang , Hsieh Ping-Chun , Hou I-Hong , Cui Shuguang , Kumar P.R. , Ekbal Amal , Kundargi Nikhil
Published: September 2015

This demo presents WiMAC, a general-purpose wireless testbed for researchers to quickly prototype a wide variety of real-time MAC protocols for wireless networks. As the interface between the link layer and the physical layer, MAC protocols are often tightly coupled with the underlying physical layer, and need to have extremely small latencies. Implementing a new MAC requires a long time. In fact, very few MACs have ever been implemented, even though dozens of new MAC protocols have been proposed. To enable quick prototyping, we employ the mechanism vs. policy separation to decompose the functionality in the MAC layer and the PHY layer. Built on the separation framework, WiMAC achieves the independence of the software from the hardware, offering a high degree of function reuse and design flexibility. Hence, our platform not only supports easy cross-layer design but also allows protocol changes on the fly. Following the 802.11-like reference design, we demonstrate that deploying a new MAC protocol is quick and simple on the proposed platform through the implementation of the CSMA/CA and CHAIN protocols.
A High-Radix, Low-Latency Optical Switch for Data Centers
Authors: Alistarh Dan , Ballani Hitesh , Costa Paolo , Funnell Adam , Benjamin Joshua , Watts Philip , Thomsen Benn
Published: September 2015

We demonstrate an optical switch design that can scale up to a thousand ports with high per-port bandwidth (25 Gbps+) and low switching latency (40 ns). Our design uses a broadcast and select architecture, based on a passive star coupler and fast tunable transceivers. In addition we employ time division multiplexing to achieve very low switching latency. Our demo shows the feasibility of the switch data plane using a small testbed, comprising two transmitters and a receiver, connected through a star coupler.
Multi-Domain Service Orchestration Over Networks and Clouds
Authors: Sonkoly Balázs , Czentye János , Szabo Robert , Jocha Dávid , Elek János , Sahhaf Sahel , Tavernier Wouter , Risso Fulvio
Published: September 2015

End-to-end service delivery often includes transparently inserted Network Functions (NFs) in the path. Flexible service chaining will require dynamic instantiation of both NFs and traffic forwarding overlays. Virtualization techniques in compute and networking, like cloud and Software Defined Networking (SDN), promise such flexibility for service providers. However, patching together existing cloud and network control mechanisms necessarily puts one over the above, e.g., OpenDaylight under an OpenStack controller. We designed and implemented a joint cloud and network resource virtualization and programming API. In this demonstration, we show that our abstraction is capable for flexible service chaining control over any technology domains.
A Framework for Collocation Error Correction in Web Pages and Text Documents
Authors: Varghese Alan , Varde Aparna S. , Peng Jing , Fitzpatrick Eileen
Published: September 2015

Much of the English in text documents today comes from nonnative speakers. Web searches are also conducted very often by non-native speakers. Though highly qualified in their respective fields, these speakers could potentially make errors in collocation, e.g., "dark money" and "stock agora" (instead of the more appropriate English expressions "black money" and "stock market" respectively). These may arise due to literal translation from the respective speaker's native language or other factors. Such errors could cause problems in contexts such as querying over Web pages, correct understanding of text documents and more. This paper proposes a framework called CollOrder to detect such collocation errors and suggest correctly ordered collocated responses for improving the semantics. This framework integrates machine learning approaches with natural language processing techniques, proposing suitable heuristics to provide responses to collocation errors, ranked in the order of correctness. We discuss the proposed framework with algorithms and experimental evaluation in this paper. We claim that it would be useful in semantically enhancing Web querying e.g., financial news, online shopping etc. It would also help in providing automated error correction in machine translated documents and offering assistance to people using ESL tools.
Addressing the Safety of Transportation Cyber-Physical Systems: Development and Validation of a Verbal Warning Utility Scale for Intelligent Transportation Systems
Authors: Zhang Yiqi , Wu Changxu , Qiao Chunming , Sadek Adel , Hulme Kevin F.
Published: September 2015

As an important application of Cyber-Physical Systems (CPS), advances in intelligent transportation systems (ITS) improve driving safety by informing drivers of hazards with warnings in advance. The evaluation of the warning effectiveness is an important issue in facilitating communication of ITS. The goal of the present study was to develop a scale to evaluate the warning utility, namely, the effectiveness of a warning in preventing accidents in general. A driving simulator study was conducted to validate the Verbal Warning Utility Scale (VWUS) in a simulated driving environment. The reliability analysis indicated a good split-half reliability for the VWUS with a Spearman-Brown Coefficient of 0.873. The predictive validity of VWUS in measuring the effectiveness of the verbal warnings was verified by the significant prediction of safety benefits indicated by variables, including reduced kinetic energy and collision rate. Compared to conducting experimental studies, this scale provides a simpler way to evaluate overall utility of verbal warnings in communicating associated hazards in intelligent transportation systems. This scale can be further applied to improve the design of warnings of ITS in order to improve transportation safety. The applications of the scale in nonverbal warning situations and limitations of the current scale are also discussed.
An Experimental QoE Performance Study for the Efficient Transmission of High Demanding Traffic over an Ad Hoc Network Using BATMAN
Authors: Sanchez-Iborra Ramon , Cano Maria-Dolores , Rodrigues Joel J. P. C. , Garcia-Haro Joan
Published: September 2015

Multimedia communications are attracting great attention from the research, industry, and end-user communities. The latter are increasingly claiming for higher levels of quality and the possibility of consuming multimedia content from a plethora of devices at their disposal. Clearly, the most appealing gadgets are those that communicate wirelessly to access these services. However, current wireless technologies raise severe concerns to support extremely demanding services such as real-time multimedia transmissions. This paper evaluates from QoE and QoS perspectives the capability of the ad hoc routing protocol called BATMAN to support Voice over IP and video traffic. To this end, two test-benches were proposed, namely, a real (emulated) testbed and a simulation framework. Additionally, a series of modifications was proposed on both protocols’ parameters settings and video-stream characteristics that contributes to further improving the multimedia quality perceived by the users. The performance of the well-extended protocol OLSR is also evaluated in detail to compare it with BATMAN. From the results, a notably high correlation between real experimentation and computer simulation outcomes was observed. It was also found out that, with the proper configuration, BATMAN is able to transmit several QCIF video-streams and VoIP calls with high quality. In addition, BATMAN outperforms OLSR supporting multimedia traffic in both experimental and simulated environments.