Numerous systems have been designed which use virtualization to subdivide the ample resources of a modern computer. Some require specialized hardware, or cannot support commodity operating systems. Some target 100% binary compatibility at the expense of performance. Others sacrifice security or functionality for speed. Few offer resource isolation or performance guarantees; most provide only best-effort provisioning, risking denial of service.This paper presents Xen, an x86 virtual machine monitor which allows multiple commodity operating systems to share conventional hardware in a safe and resource managed fashion, but without sacrificing either performance or functionality. This is achieved by providing an idealized virtual machine abstraction to which operating systems such as Linux, BSD and Windows XP, can be ported with minimal effort.Our design is targeted at hosting up to 100 virtual machine instances simultaneously on a modern server. The virtualization approach taken by Xen is extremely efficient: we allow operating systems such as Linux and Windows XP to be hosted simultaneously for a negligible performance overhead --- at most a few percent compared with the unvirtualized case. We considerably outperform competing commercial and freely available solutions in a range of microbenchmarks and system-wide tests.

/pdf/xen-and-the-art-of-virtualization-vt3kaikb6y.pdf

Xen and the art of virtualization

This document provides updates to IEEE Std 802.16's MIB for the MAC, PHY and asso- ciated management procedures in order to accommodate recent extensions to the standard.

IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems Draft Amendment: Management Information Base Extensions

Wireless sensor network (WSN) has emerged as one of the most promising technologies for the future. This has been enabled by advances in technology and availability of small, inexpensive, and smart sensors resulting in cost effective and easily deployable WSNs. However, researchers must address a variety of challenges to facilitate the widespread deployment of WSN technology in real-world domains. In this survey, we give an overview of wireless sensor networks and their application domains including the challenges that should be addressed in order to push the technology further. Then we review the recent technologies and testbeds for WSNs. Finally, we identify several open research issues that need to be investigated in future.

Our survey is different from existing surveys in that we focus on recent developments in wireless sensor network technologies. We review the leading research projects, standards and technologies, and platforms. Moreover, we highlight a recent phenomenon in WSN research that is to explore synergy between sensor networks and other technologies and explain how this can help sensor networks achieve their full potential. This paper intends to help new researchers entering the domain of WSNs by providing a comprehensive survey on recent developments.

Wireless sensor networks: a survey on recent developments and potential synergies

In a packet network, the terms bandwidth and throughput often characterize the amount of data that the network can transfer per unit of time. Bandwidth estimation is of interest to users wishing to optimize end-to-end transport performance, overlay network routing, and peer-to-peer file distribution. Techniques for accurate bandwidth estimation are also important for traffic engineering and capacity planning support. Existing bandwidth estimation tools measure one or more of three related metrics: capacity, available bandwidth, and bulk transfer capacity. Currently available bandwidth estimation tools employ a variety of strategies to measure these metrics. In this survey we review the recent bandwidth estimation literature focusing on underlying techniques and methodologies as well as open source bandwidth measurement tools.

/pdf/bandwidth-estimation-metrics-measurement-techniques-and-4hy3a2hfca.pdf

Bandwidth estimation: metrics, measurement techniques, and tools

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[서평]「Computer Organization and Design, The Hardware/Software Interface」

We present a network friendly bandwidth measurement method, TOPP, that is based on active probing and includes analysis by segmented regression. This method can estimate two complementing available bandwidth metrics in addition to the link bandwidth of the congested link. Contrary to traditional packet pair estimates of the bottleneck link bandwidth, our estimate is not limited by the rate at which we can inject probe packets into the network. We also show that our method is able to detect bottlenecks that are invisible to methods such as the C-probe. Further more, we describe scenarios where our analysis method is able to calculate bandwidth estimates for several congested hops based on a single end-to-end probe session.

A new end-to-end probing and analysis method for estimating bandwidth bottlenecks

After almost a decade of research into ad hoc networking, MANET technology has not yet affected our way of using wireless networks. In this paper we discuss lessons to draw and back them with experiences from our experimental work. We find that simulations have to be complemented to a much higher degree by real-world experiments, that there is a lack of mature implementations and integration and that efforts should be focused on more realistic settings inside the ''ad hoc horizon'' where decent network services still can be provided.

/pdf/lessons-from-experimental-manet-research-ym19wlzg8i.pdf

Lessons from experimental MANET research

Sensor networks that operate in the unlicensed 2.4~GHz frequency band suffer cross-technology radio interference from a variety of devices, e.g., Bluetooth headsets, laptops using WiFi, or microwave ovens. Such interference has been shown to significantly degrade network performance. We present SoNIC, a system that enables resource-limited sensor nodes to detect the type of interference they are exposed to and select an appropriate mitigation strategy. The key insight underlying SoNIC is that different interferers disrupt individual 802.15.4 packets in characteristic ways that can be detected by sensor nodes. In contrast to existing approaches to interference detection, SoNIC does not rely on active spectrum sampling or additional hardware, making it lightweight and energy-efficient.In an office environment with multiple interferers, a sensor node running SoNIC correctly detects the predominant interferer 87% of the time. To show how sensor networks can benefit from SoNIC, we add it to a mobile sink application to improve the application's packet reception ratio under interference.

http://user.it.uu.se/~frehe489/publications/hermans13sonic.pdf

SoNIC: classifying interference in 802.15.4 sensor networks

Recent events (earthquakes, floods, etc.) have shown that users heavily rely on online social networks (OSN) to communicate and organize during disasters and in their aftermath. In this paper, we discuss what features could be added to OSN apps for smart phones -- for the example of Twitter -- to make them even more useful for disaster situations. In particular, we consider cases where the fixed communication infrastructure is partially or totally wiped out and propose to equip regular Twitter apps with a disaster mode. The disaster mode relies on opportunistic communication and epidemic spreading of Tweets from phone to phone. Such "disaster-ready" applications would allow to resume (although limited) communication instantaneously and help distressed people to self-organize until regular communication networks are functioning again, or, temporary emergency communication infrastructure is installed.We argue why we believe that Twitter with its simplicity and versatile features (e.g., retweet and hashtag) is a good platform to support a variety of different situations and present Twimight, our disaster ready Twitter application. In addition, we propose Twimight as a platform for disseminating sensor data providing information such as locations of drinkable water sources. Eventually, we propose to rely on interest matching to scale Twitter hashtag-based searches in an opportunistic environment. The combination of these features make our opportunistic Twitter the ideal emergency kit in situations of disasters. We discuss and define the main implementation and research challenges (both technical and non-technical).

Twitter in disaster mode: opportunistic communication and distribution of sensor data in emergencies

The Content-Centric Networking (CCN) architecture, a clean-slate network design, borrows its routing concepts from IP. If content is located on mobile sources, CCN also inherits some of the mobility problems known from IP. In this paper, we explore the design space of CCN mobility solutions by revisiting well-known IP approaches that aim to solve a remarkably similar problem. While mobility solutions may be quite similar in both architectures, we find that a locator/identifier split should be implemented at the network layer in CCN to prevent temporary, topology-dependent information to leak into content that ought to be permanent. Mobility handling further benefits from CCN's security model and multipath forwarding. To provide a starting point for further research, we present a simple mobility approach based on an explicit locator/identifier split.

http://user.it.uu.se/~frehe489/docs/12_ccn_source_mobility.pdf

Per Gunningberg

Papers

A new end-to-end probing and analysis method for estimating bandwidth bottlenecks

Lessons from experimental MANET research

SoNIC: classifying interference in 802.15.4 sensor networks

Twitter in disaster mode: opportunistic communication and distribution of sensor data in emergencies

Global source mobility in the content-centric networking architecture