Showing papers on "Testbed published in 2003"

A blueprint for introducing disruptive technology into the Internet

Abstract: This paper argues that a new class of geographically distributed network services is emerging, and that the most effective way to design, evaluate, and deploy these services is by using an overlay-based testbed. Unlike conventional network testbeds, however, we advocate an approach that supports both researchers that want to develop new services, and clients that want to use them. This dual use, in turn, suggests four design principles that are not widely supported in existing testbeds: services should be able to run continuously and access a slice of the overlay's resources, control over resources should be distributed, overlay management services should be unbundled and run in their own slices, and APIs should be designed to promote application development. We believe a testbed that supports these design principles will facilitate the emergence of a new service-oriented network architecture. Towards this end, the paper also briefly describes PlanetLab, an overlay network being designed with these four principles in mind.

RABBIT: a testbed for advanced control theory

Abstract: Describes the design, construction and control of an experimental bipedal robot platform for the study of walking.

A Remote Code Update Mechanism for Wireless Sensor Networks

Abstract: : Wireless sensor networks consist of collections of small, low-power nodes that interface or interact with the physical environment. The ability to add new functionality or perform software maintenance without having to physically reach each individual node is already an essential service, even at the limited scale at which current sensor networks are deployed. TinyOS supports single-hop over-the-air reprogramming today, but the need to reprogram sensors in a multi-hop network will become particularly critical as sensor networks mature and move toward larger deployment sizes. In this paper we present Multihop Over-the-Air Programming (MOAP), a code distribution mechanism specifically targeted for Mica-2 Motes. We discuss and analyze the design goals, constraints, choices and optimizations focusing in particular on dissemination strategies and retransmission policies. We have implemented MOAP on Mica-2 motes and we evaluate that implementation using both emulation and testbed experiments. We show that our dissemination mechanism obtains a 60-90% performance improvement in terms of required transmissions compared to flooding. We also show that a very simple windowed retransmission tracking scheme is nearly as effective as arbitrary repairs and yet is much better suited to energy and memory constrained embedded systems.

Scriptroute: a public internet measurement facility

Abstract: We present Scriptroute, a system that allows ordinary Internet users to conduct network measurements from remote vantage points. We seek to combine the flexibility found in dedicated measurement testbeds such as NIMI with the general accessibility and popularity of Web-based public traceroute servers. To use Scriptroute, clients use DNS to discover measurement servers and then submit a measurement script for execution in a sandboxed, resource-limited environment. The servers ensure that the script does not expose the network to attack by applying source- and destination-specific filters and security checks, and by rate-limiting traffic. Scriptroute code is publicly available and has been deployed on the PlanetLab testbed of 42 sites. As proof-of-concept, we have used it both to create RPT, a tool for measuring routing trees toward a destination, and to repeat the experiment used to evaluate GNP, a recently proposed Internet distance estimation technique. We find that our system is flexible enough to implement a variety of measurement tools despite its security restrictions, that access to many remote vantage points makes the system valuable, and that scripting is an apt choice for expressing and combining measurement tasks.

Lightweight sensing and communication protocols for target enumeration and aggregation

Abstract: The development of lightweight sensing andcommunication protocols is a key requirement for designing resource constrained sensor networks. This paper introduces a set of efficient protocols and algorithms, DAM, EBAM, and EMLAM, for constructing and maintaining sensor aggregates that collectively monitor target activity in the environment. A sensor aggregate comprises those nodes in a network that satisfy a grouping predicate for a collaborative processing task. The parameters of the predicate depend on the task and its resource requirements. Since the foremost purpose of a sensor network is to selectively gather information about the environment, the formation of appropriate sensor aggregates is crucial for optimally allocating resources to sensing and communication tasks.This paper makes minimal assumptions about node onboard processing and communication capabilities so as to allow possible implementations on resource-constrained hardware. Factors affecting protocol performance are discussed. The paper presents simulation results showing how the protocol performance varies as key network and task parameters are varied. It also provides probabilistic analyses of network behavior consistent with the simulation results. The protocols have been experimentally validated on a sensor network testbed comprising 25 Berkeley MICA sensor motes.

Using graphic turing tests to counter automated DDoS attacks against web servers

Abstract: We present WebSOS, a novel overlay-based architecture that provides guaranteed access to a web server that is targeted by a denial of service (DoS) attack. Our approach exploits two key characteristics of the web environment: its design around a human-centric interface, and the extensibility inherent in many browsers through downloadable "applets." We guarantee access to a web server for a large number of previously unknown users, without requiring pre-existing trust relationships between users and the system.Our prototype requires no modifications to either servers or browsers, and makes use of graphical Turing tests, web proxies, and client authentication using the SSL/TLS protocol, all readily supported by modern browsers. We use the WebSOS prototype to conduct a performance evaluation over the Internet using PlanetLab, a testbed for experimentation with network overlays. We determine the end-to-end latency using both a Chord-based approach and our shortcut extension. Our evaluation shows the latency increase by a factor of 7 and 2 respectively, confirming our simulation results.

Target classification and localization in habitat monitoring

Abstract: We are developing an acoustic habitat-monitoring sensor network that recognizes and locates specific animal calls in real time. We investigate the system requirements of such a real-time acoustic monitoring network. We propose a system architecture and a set of lightweight collaborative signal processing algorithms that achieve real-time behavior while minimizing inter-node communication to extend the system lifetime. In particular, the target classification is based on spectrogram pattern matching while the target localization is based on beamforming using time difference of arrival (TDOA). We describe our preliminary implementation on a commercial off the shelf (COTS) testbed and present its performance based on testbed measurements.

A summary of the HORNET project: a next-generation metropolitan area network

Abstract: Metropolitan area networks are currently undergoing an evolution aimed at more efficiently transport of data-oriented traffic. However, the incoming generation of metro networks is based on conventional technology, which prevents them scaling cost-effectively to ultrahigh capacities. We have developed a new architecture and set of protocols for the next generation of metro networks. The architecture, named HORNET (hybrid optoelectronic ring network), is a packet-over-wavelength-division multiplexing ring network that utilizes fast-tunable packet transmitters and wavelength routing to enable it to scale cost-effectively to ultrahigh capacities. A control-channel-based media access control (MAC) protocol enables the network nodes to share the bandwidth of the network while preventing collisions. The MAC protocol is designed to transport variable-sized packets and to provide fairness control to all network end users. The efficiency and the fairness of the MAC protocol is demonstrated with custom-designed simulations. The implementation of the MAC protocol and the survivability of the network have been demonstrated in a laboratory experimental testbed. The article summarizes the accomplishments of the HORNET project, including the design, analysis, and demonstration of a metro architecture and a set of protocols. The HORNET architecture is an excellent candidate for next-generation high-capacity metro networks.

Using random subsets to build scalable network services

Abstract: In this paper, we argue that a broad range of large-scale network services would benefit from a scalable mechanism for delivering state about a random subset of global participants. Key to this approach is ensuring that membership in the subset changes periodically and with uniform representation over all participants. Random subsets could help overcome inherent scaling limitations to services that maintain global state and perform global network probing. It could further improve the routing performance of peer-to-peer distributed hash tables by locating topologically-close nodes. This paper presents the design, implementation, and evaluation of RanSub, a scalable protocol for delivering such state. As a first demonstration of the RanSub utility, we construct SARO, a scalable and adaptive application-layer overlay tree. SARO uses RanSub state information to locate appropriate peers for meeting application-specific delay and bandwidth targets and to dynamically adapt to changing network conditions. A large-scale evaluation of 1000 overlay nodes participating in an emulated 20,000- node wide-area network topology demonstrate both the adaptivity and scalability (in terms of per-node state and network overhead) of both RanSub and SARO. Finally, we use an existing streaming media server to distribute content through SARO running on top of the PlanetLab Internet testbed.

BANANAS: an evolutionary framework for explicit and multipath routing in the internet

Abstract: Today the Internet offers a single path between end-systems even though it intrinsically has a large multiplicity of paths. This paper proposes an evolutionary architectural framework "BANANAS" aimed at simplifying the introduction of multipath routing in the Internet. The framework starts with the observation that a path can be encoded as a short hash ("PathID") of a sequence of globally known identifiers. The PathID therefore has global significance (unlike MPLS or ATM labels). This property allows multipath capable nodes to autonomously compute PathIDs in a partially upgraded network without requiring an explicit signaling protocol for path setup. We show that this framework allows the introduction of sophisticated explicit routing and multipath capabilities within the context of widely deployed connectionless routing protocols (e.g. OSPF, IS-IS, BGP) or overlay networks. We establish these characteristics through the development of PathID encoding and route-computation schemes. The BANANAS framework also allows considerable flexibility in terms of architectural function placement and complexity management. To illustrate this feature, we develop an efficient variable-length hashing scheme that moves control-plane complexity and state over-heads to network edges, allowing a very simple interior node design. All the schemes have been evaluated using both sizable SSFNet simulations and Linux/Zebra implementation evaluated on Utah's Emulab testbed facility.

EWANT: the emulated wireless ad hoc network testbed

Abstract: In this paper we demonstrate a wireless 802.11 testbed. This testbed allows for direct comparison between mobile wireless routing protocols without affecting their routing or MAC layer protocols or inter-layer interaction. We have built a low cost environment to facilitate such wireless network research. The core idea is "compressing" the network and emulating mobility without actually moving the nodes. We successfully emulate the RF effects along with mobility. The viability of this test bed is checked with the help of a click implementation of the dynamic source routing protocol. Our experiences show that such a testbed provides valuable feedback not available through simulation.

An FPGA based rapid prototyping platform for MIMO systems

Abstract: Multiple input multiple output (MIMO) techniques hold the potential of dramatically increasing the data rates and spectral efficiency of wireless communications systems. Even with extensive research on the design of transmission and reception algorithms, little is known as to how much of the predicted gains are actually achievable on real wireless channels. In this paper, we present a MIMO testbed, which enables the rapid prototyping of MIMO transceivers for wideband channels. Such prototypes provide experimental quantification of achievable gains from MIMO algorithms. The testbed design allows real-time operation of baseband processing and RF up/down-conversion. The choice of testbed components is made to allow maximum, flexibility for research purposes, including monitoring and control of all subsystems. In addition to discussing the testbed's design, we present the implementation of two wireless systems. The first is a spread-spectrum system based on IEEE 802.11b. The second is an implementation of Alamouti's transmit diversity scheme.

An entity maintenance and connection service for sensor networks

Abstract: In this paper, we present a middleware architecture for coordination services in sensor networks that facilitates interaction between groups of sensors which monitor different environmental events. It sits on top of the native routing infrastructure and exports the abstraction of mobile communication endpoints maintained at the locations of such events. A single logical destination is created and maintained for every environmental event of interest. Such destinations are uniquely labeled and can be used for communication by application-level algorithms for coordination and sensory data management between the different event locales. For example, they may facilitate coordination, in a distributed intrusion scenario, among nodes in the vicinity of the intruders.We evaluate our middleware architecture using GloMoSim, a wireless network simulator. Our results illustrate the success of our architecture in maintaining event-related communication endpoints. We provide an analysis of how architectural and network dependent parameters affect our performance. Additionally we provide a proof of concept implementation on a real sensor network testbed (Berkeley's MICA Motes).

The RoboFlag testbed

Abstract: This paper describes the RoboFlag hardware/software testbed. The RoboFlag game consists of two teams of 6-10 robots and 2 people, each attempting to capture the other teams flag while defending their own. Limited sensing capability, distributed processing, and limited bandwidth communications are integral parts of the system. The game can be played with real robots or with simulated robots. Some aspects of the game, such as the arbiter and communications network, are completely simulated.

Just-in-time optical burst switching implementation in the ATDnet all-optical networking testbed

Abstract: We describe: (i) the architecture of an optical burst switched (OBS) demonstration network overlaying the ATDnet transparent all-optical testbed, and (ii) experiments underway in the testbed. The OBS overlay uses a simple hardware-based protocol embedded in OBS network controllers to manage commercial off-the-shelf DWDM switches. Data paths are all-optical and completely transparent, and can carry analog or digital traffic in any format, data rate, and modulation scheme. Experiments with latency- and jitter-sensitive HDTV transmission, petabyte file transfers, and immersive real time visualization of satellite imagery over the OBS network are ongoing. Parallel research on transport protocols, QoS-aware routing protocols, adaptors for an OBS LAN, and network management architecture are applied as completed. This is the first just-in-time (JIT) OBS field trial known to the authors.

Network mobility from the InternetCAR perspective

Abstract: A number of devices, including sensors, mobile telephones, and various computers will be deployed in next generation vehicles, and interconnected on a local network. These vehicles will be connected to the Internet as both a step toward ubiquitous computing and as a means to meet intelligent transportation systems (ITS) needs. For doing so, the communication system requirements are investigated in the InternetCAR project, particularly IPv6 and network mobility support which is mandated to maintain ongoing sessions as the in-vehicle embedded network changes its point of attachment to the Internet topology. In order to deal with the specific issues raised by network mobility, which contrast with traditional work on host mobility, the IETF NEMO working group has been set up. The initial proposition for doing so, prefix scope binding updates, is implemented in our testbed, designed to demonstrate the proposed communication system.

GNOMES: a testbed for low power heterogeneous wireless sensor networks

Abstract: Continuing trends in sensor, semiconductor and communication systems technology (smaller, faster, cheaper) make feasible very dense networks of fixed and mobile wireless devices for use in many different sensing and decision-making systems. In this paper we present the design and development of GNOMES, a low-cost hardware and software testbed. This testbed was designed to explore the properties of heterogeneous wireless sensor networks, to test theory in sensor networks architecture, and be deployed in practical application environments. We also present an overview of architectures for extending the lifetime of individual nodes in the network, along with the design tradeoffs that this presents.

MULTIPLATFORM testbed: an integration platform for multimodal dialog systems

Abstract: Modern dialog and information systems are increasingly based on distributed component architectures to cope with all kinds of heterogeneity and to enable flexible re-use of existing software components. This contribution presents the MULTIPLATFORM testbed as a powerful framework for the development of integrated multimodal dialog systems. The paper provides a general overview of our approach and explicates its foundations. It describes advanced sample applications that have been realized using the integration platform and compares our approach to related works.

Workload and Failure Characterization on a Large-Scale Federated Testbed

Abstract: Recently, a number of federated distributed computational and communication infrastructures have emerged, including the Grid, PlanetLab, and Content Distribution Networks. In these environments, mutually distrustful autonomous domains pool resources together for their mutual benefit, for instance to gain access to: unique computational resources, multiple vantage points on the network, or more computation than available locally. Key challenges for such federated infrastructures include resource allocation, scheduling, and constructing highly available services in the face of faulty end hosts and unpredictable network behavior. Developing such appropriate mechanisms and policies requires an understanding of the usage characteristics and operating environment of the target environment. In this paper, we present a detailed characterization of the actual use of the PlanetLab network testbed. PlanetLab consists of 240 nodes spread across 100 autonomous domains with over 500 active users. Using a variety of measurement tools, we present a three-month study on the network, CPU, memory and disk usage of individual PlanetLab nodes and sites. On the consumer side, we further characterize the consumption of individual users. Next, we present results on the availability and reliability of system nodes and the network interconnecting them. Finally, we discuss the implications of our measurements for emerging federated environments.

Research and design of a mobile streaming media content delivery network

Abstract: Delivering media to large numbers of mobile users presents challenges due to the stringent requirements of streaming media, mobility, wireless, and scaling to support large numbers of users. This paper presents a mobile streaming media content delivery network (MSM-CDN) designed to overcome these challenges. The MSM-CDN is a network overlay consisting of overlay servers on top of the existing network; these overlay servers are control points that facilitate end-to-end media delivery and mid-network media services. This paper presents an overview of the MSM-CDN system architecture, and describes the testbed prototype that we built based on these architectural principles. The MSM-CDN provides a new platform for media delivery, and we describe a number of research directions related to the MSM-CDN.

Benchmarking the performance of manufacturing control systems: design principles for a web-based simulated testbed

Abstract: The paper reports the main research activities currently carried out for designing and developing a test-bench service. This service would act as the main reference point for establishing benchmarks on which research results can be compared. These benchmarks will be made available through web technology. The paper, after a first outline of the main features of the project and its overall vision, is particularly focused both on the design principles related to the construction of good benchmark cases and on the technological issues related to the provision of a web-based simulation environment for supporting interactivity between remote scheduling and control systems and a locally resident simulation system.

Periodic broadcast and patching services - implementation, measurement and analysis in an internet streaming video testbed

Abstract: Multimedia streaming applications can consume a significant amount of server and network resources Periodic broadcast and patching are two approaches that use multicast transmission and client buffering in innovative ways to reduce server and network load, while at the same time allowing asynchronous access to multimedia streams by a large number of clients Current research in this area has focussed primarily on the algorithmic aspects of these approaches, with evaluation performed via analysis or simulation In this paper, we describe the design and implementation of a flexible streaming video server and client test bed that implements both periodic broadcast and patching, and explore the issues that arise when implementing these algorithms using laboratory and internet-based test beds We present measurements detailing the overheads associated with the various server components (signaling, transmission schedule computation, data retrieval and transmission), the interactions between the various components of the architecture, and the overall end-to-end performance We also discuss the importance of an appropriate server application-level caching policy for reducing the needed disk bandwidth at the server We conclude with a discussion of the insights gained from our implementation and experimental evaluation

WIND-FLEX: developing a novel testbed for exploring flexible radio concepts in an indoor environment

Abstract: We describe the essential features of a novel testbed, code-named WIND-FLEX and developed under the auspices of the EU IST research program, whose primary goal has been to define and explore concepts related to radio flexibility, with application to an OFDM-based short-range indoor radio transceiver design. The emphasis has been on the profitable use of software and DSP tools for the purpose of demonstrating adaptivity and reconfigurability features, primarily for the lower layers (i.e., PHY and DLC/MAC layers). The topics covered briefly herein include the meaning of the terms in the present context, their instantiation in the design, their contribution to an optimized low-transmit-power scheme, the novel elements required in order to achieve it, the contribution to a guaranteed QoS philosophy, and the relationship of the testbed to broader software-defined-radio concepts.

Adaptive power control and selective radio activation for low-power infrastructure-mode 802.11 LANs

Abstract: We present an integrated dual approach to reduce power consumption in infrastructure-mode 802.11 wireless LANs. A novel distributed power control algorithm adoptively adjusts the transmit power of the 802.11 radio/NIC to achieve power savings in the presence of mobility and RF noise. An adaptive radio activation algorithm selectively sleeps the 802.11 radio/NIC, to reduce idle power consumption. We analyze the performance of these algorithms in an 802.11 testbed using Web traces of HTTP/TCP user data accesses. Our application-level architecture integrates the two approaches into an incrementally deployable and application-transparent solution for power management of the RF interface on 802.11-enabled laptops.

vBET: a VM-based emulation testbed

Abstract: With the increasing requirement of robustness and predictability for network protocols and distributed systems, it becomes necessary to develop realistic, customizable, and scalable emulation testbeds for the testing and evaluation of network and distributed protocols. A number of recently proposed emulation testbeds have clearly demonstrated the advantage and promise of this approach. Meanwhile, more efforts are necessary to achieve higher degree of flexibility and customizability, especially for the creation of arbitrary network topology and for the customization of network-level entities.In this paper, we present vBET, an efficient and flexible emulation testbed using the virtual machine technology. Based on Linux, vBET can be installed in a high-end desktop or a commodity server and is therefore easily deployable in a research lab. vBET creates a virtual distributed environment with both network infrastructure and end systems. Each entity, such as a router, switch, firewall, or application-level proxy, is emulated by a virtual machine running unmodified system or application software. The entities emulated by vBET are user-configurable. Furthermore, the same (physical) vBET server can be easily setup as testbed for different experiments, such as Internet routing, distributed firewalls, and peer-to-peer networks.We describe the design, implementation, and application of vBET. For the design and implementation, we present key enabling techniques including virtual OS, virtual networking, and small-footprint file system. For the application of vBET, we demonstrate the creation of different experimental environments using vBET, including OSPF routing, distributed firewall, and Chord peer-to-peer network. These experiments reflect the versatility, customizability, and efficiency of vBET.

Towards a testbed for multi-party dialogues

Abstract: In many situations conversations involve more than two parties. However, most research on communication modelling in e.g. multi-agent systems limits itself to conversations between two parties at a time. Very little research has been done yet on modelling multi-party dialogues. In this paper we first explore the differences between two party and multi-party dialogues and we indicate a number of issues that arise when considering dialogues between more than two parties. Then we take some steps towards creating a testbed in which these issues can be explored and theory on multi-party dialogues can be developed.

Transport Protocol Optimization for Energy Efficient Wireless Embedded Systems

Abstract: For wireless embedded systems, the power consumption in the network interface (radio) plays a dominant role in determining battery life. In this paper, we explore transport protocol optimizations for reducing the energy consumption of wireless LAN interfaces. Our work is based on the observation that, the transport protocol, which implements flow control to regulate the network traffic, plays a significant role in determining the workload of the network interface. Hence, by monitoring run-time parameters in the transport protocol, coarse-granularity idle periods, which present the best opportunities for network interface power reduction, can be accurately identified. We further show that, by tuning parameters in the protocol software implementation, we can shape the activity profile of the network interface, making it more energy efficient while remaining compliant to the TCP standard. We have performed extensive current measurements using an experimental testbed that consists of a Compaq iPAQ PDA with a Cisco Aironet wireless network adapter, to validate the proposed techniques. Our measurements indicate energy savings ranging from 28% to 69% compared to the use of state-of-the-art MAC layer power reduction techniques, with little or no impact on performance.

Architecture and operation of an adaptable communication substrate

Abstract: This paper describes the internal architecture and operation of an adaptable communication component called the MetaSocket. MetaSockets are created using Adaptive Java, a reflective extension to Java that enables a component's internal architecture and behavior to be adapted at run time in response to external stimuli. This paper describes how adaptive behavior is implemented in MetaSockets, as well as how MetaSockets interact with other adaptive components, such as decision makers and event mediators. Results of experiments on a mobile computing testbed demonstrate how MetaSockets respond to dynamic wireless channel conditions in order to improve the quality of interactive audio streams delivered to iPAQ handheld computers.

Dynamic Creation and Management of Runtime Environments in the Grid

Abstract: In this paper, we describe architecture and interfaces designed to support dynamic, secure creation and management of runtime environments (such as local Unix accounts) in the Grid based on authentication and authorization of a user. These abstractions are designed to allow users to create and manage runtime environments in a uniform manner across different technologies. We begin by describing support for individual dynamic environments and ways in which a composition of such environments can be created. We then present how we leverage these concepts in the PlanetLab testbed to build GSLab, a distributed platform for deploying and experimenting with Grid Services. Previous work on dynamic accounts [3-5] has not presented a unified abstraction, nor has it addressed management problems in complex distributed environments like the Grid. In this paper, we lay out the

An S-band digital array radar testbed

Abstract: Future naval radars will perform a combination of functions including volume search, track, and high resolution imaging. These radars, which must operate in littoral regions (i.e., near coastlines), will need to contend with strong clutter and jamming. As such, digital phased array technology, wherein transmit and receive signals are digitized at (or near) the antenna element, can offer significant advantages. However, it appears that digitizing a large wideband microwave phased array has never before been attempted. Directly fielding such a system would come with some perceived risks; many of these risks can be mitigated through the development of a small scale testbed. Recently, MIT Lincoln Laboratory funded the development of a wideband digital array radar testbed. The system consists of a 14' reconfigurable digital linear array aperture, 500+MHz imaging bandwidth, 90+dB dynamic range, and element-level digital recording. The initial system configuration uses direct digital waveform synthesis, analog signal distribution, and stretch processing at the receivers. Digital downconversion, time-delay beamsteering, and space-time adaptive processing (STAP) are performed by an offline processor. This paper provides an overview of the testbed's design and construction. Initial test results are also presented.