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The Networks Group meets regularly throughout the year for informal discussions, presentations, and a reading group.

Unless otherwise indicated, the informal meetings will be held every Wednesday at 4pm until 5pm in room 6.12, and usually last about an hour. We have moved building located here. (check the deptartmental room bookings page or the central college room bookings page if in doubt). Please contact Felipe Huici (f.huici@cs.ucl.ac.uk) if you have any questions or if you would like to book a seminar slot for a speaker.

January 2005

  • January 19

  • January 26 : No seminar all staff away.
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February 2005

  • February 2 : Reading Group
    Speaker: Manish Lad
    Paper: Tussle in Cyberspace: Defining Tomorrows Internet, David D. Clark, John Wroclawski, Karen R. Sollins (MIT LCS), Robert Braden (USC), Proc. Sigcomm 2002.
    Abstract: The architecture of the Internet is based on a number of principles, including the self-describing datagram packet, the end to end arguments, diversity in technology and global addressing. As the Internet has moved from a research curiosity to a recognized component of mainstream society, new requirements have emerged that suggest new design principles, and perhaps suggest that we revisit some old ones. This paper explores one important reality that surrounds the Internet today: different stakeholders that are part of the Internet milieu have interests that may be adverse to each other, and these parties each vie to favor their particular interests. We call this process ``the tussle''. Our position is that accommodating this tussle is crucial to the evolution of the network's technical architecture. We discuss some examples of tussle, and offer some technical design principles that take it into account.

  • February 9
    Speaker:Prof. Lee W. McKnight
    Title:Virtual Markets in Wireless Grids
    Wireless grids, a new type of resource-sharing network, connect sensors, mobile phones, notebook computers and other edge devices with each other and with wired grids.

    Ad hoc distributed resource sharing allows these devices to offer new resources and locations of use for grid computing. Users - and their devices - may buy, sell, or give away resources in virtual markets that are created, and destroyed, as people and their devices, move through real and virtual spaces through wireless grids.

    In this talk Professor Lee W. McKnight will discuss the US National Science Foundation-supported research effort he leads involving faculty and students at Syracuse, Tufts, Boston, and Northeastern Universities, as well as MIT and ETHZ to develop technology and theory for wireless grids.

  • February 16 : Group Meeting

  • February 23

March 2005

  • March 2
    Speaker : Julian Chesterfield (Computer Lab.,Uni. of Cambridge)
    Title:Exploiting Diversity to enhance multimedia streaming over cellular links
    Abstract: "Wireless Wide Area Networks (WWANs) are becoming ubiquitous across most geographic regions, enabling simultaneous coverage from multiple providers. In europe, technologies such as GPRS and UMTS are being combined to provide an adaptive, high connectivity roaming environment as operators strive to identify novel applications and services for their customers, typically involving interactive multimedia streaming. An aspect of the WWAN environment however which is often under-estimated in the deployment of services is that channels exhibit both uncorrelated and correlated behaviour on a variety of levels which can be exploited. In this talk I will examine the statistical properties of WWAN links from an application level perspective, and illustrate the benefits in heterogeneity that can be exploited to improve statistical throughput and Multimedia streaming quality. Based on some fundamental observations of the WWAN environment we have designed and implemented a multimedia streaming application called 'vorbistreamer' that leverages WWAN diversity to support an Unequal Error Protection coding technique. I will present results from the evaluation of 'vorbistreamer' over operational WWAN networks, illustrating the benefits that can be derived through the use of more intelligent application coding." Based on an INFOCOM 05 talk.

  • March 9 Reading Group
    Speaker: Yangcheng Huang
    Paper: A Comparison of Hard-state and Soft-state Signaling Protocols, Ping Ji, Zihui Ge, Jim Kurose, Don Towsley, Sigcomm 2003.
    Abstract: One of the key infrastructure components in all telecommunication networks, ranging from the telephone network, to VC-oriented data networks, to the Internet, is its signaling system. Two broad approaches towards signaling can be identified: so-called hard-state and soft-state approaches. Despite the fundamental importance of signaling, our understanding of these approaches - their pros and cons and the circumstances in which they might best be employed - is mostly anecdotal (and occasionally religious). In this paper, we compare and contrast a variety of signaling approaches ranging from a "pure" soft state, to soft-state approaches augmented with explicit state removal and/or reliable signaling, to a "pure" hard state approach. We develop an analytic model that allows us to quantify state inconsistency in single- and multiple-hop signaling scenarios, and the "cost" (both in terms of signaling overhead, and application-specific costs resulting from state inconsistency) associated with a given signaling approach and its parameters (e.g., state refresh and removal timers). Among the class of soft-state approaches, we find that a soft-state approach coupled with explicit removal substantially improves the degree of state consistency while introducing little additional signaling message overhead. The addition of reliable explicit setup/update/removal allows the soft-state approach to achieve comparable (and sometimes better) consistency than that of the hard-state approach.

  • March 16
    Speaker: Richard Clayton, Computer Lab., Cambridge
    Title: Anti-Spam and Anti-Phishing : a Reality Check

  • March 23 : Last teaching day of 2nd term, college closes at 5.30pm

  • March 30 : No seminar as College re-opens on the 30th March

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April 2005

  • April 6
    Speaker:Mark Handley

  • April 13

  • April 20

  • April 27

September 2005

  • September 6
    Speaker: Ran Atkinson
    Title: ILNP: A new network-layer protocol
    Abstract: This will provide an overview of ILNP, which is a network-layer protocol being designed as part of research into naming in networked systems. The talk will also talk about changes to surrounding infrastructure that are needed to enable ILNP.
  • September 7
    Speaker: Irek Szczesniak (joint work with Damon Wischik)
    Title: Simulation of TCP performance with optical buffers
    Abstract: We are going to review optical buffers and how they fit into optical packet switching (OPS). Hopefully, we will present some preliminary simulation results of TCP flows passing through optical buffers. Currently optical backbone networks are able to switch separate wavelengths. OPS, however, promises to deliver switching at the packet level, which should utilize more efficiently and flexibly the backbone network capacity. The aim of our ongoing work is to study different architectures of optical buffers and their impact on TCP performance.
    Irek is going to present some ideas on hardware simulation where he's hoping to simulate thousands of TCP flows over a 10-Gb/s link on two Linux laptops.

  • September 14
    Speaker:Tristan Henderson, Dartmouth College
    Title: Measuring a campus-wide wireless network
    Abstract: Dartmouth College is an American liberal arts college with 5,000 students living and studying on a campus of 200 acres. The college has had campus-wide 802.11 wireless network coverage since 2001, and we have been measuring various aspects of network usage since this initial network installation. In this talk I will discuss the methods that we have used to measure the network, and some of the challenges in improving wireless network measurement. I will also talk about some uses for and results from our collected data, and our new plans for a community wireless data archive.
    Bio: Tristan Henderson is a Research Assistant Professor of Computer Science at Dartmouth College. His research interests include wireless network measurement, wireless security and networked multiplayer games. He has an MA in Economics from Cambridge and an MSc and PhD in Computer Science from UCL.

October 2005

  • October 5
    Speaker: Brad Karp
    Title: Topics in Wireless Sensor Networks, Internet Worm Defense, and Internet-Scale Distributed Systems
    Abstract: In this talk, by way of introducing myself to my new colleagues at UCL CS, I'll give a broad overview of my research interests in networked computer systems. These interests fall broadly in three categories: scalable routing for wireless networks, internet worm defense, and internet-Scale Distributed Systems. In all three of these areas, I'll motivate the problem, define technical challenges, describe novel algorithmic solutions, and describe real, running systems I've built on those algorithmic foundations.
    Bio: Brad Karp is a Senior Lecturer at UCL and a visiting Faculty Consultant at Intel Research Cambridge and Pittsburgh

  • October 26
    Speaker: Meng How Lim (Cambridge Computer Lab)
    Title: Landmark Guided Forwarding
    Abstract: In this paper we focus on the problems of maintaining Ad Hoc network connectivity in the presence of node mobility whilst providing globally efficient and robust routing. The common approach among existing wireless Ad Hoc routing solutions is to establish a global optimal path between a source and a destination. We argue that establishing a globally optimal path is both unreliable and unsustainable as the network diameter, traffic volume and number of nodes all increase in the presence of moderate node mobility. To address this we propose Landmark Guided Forwarding (LGF), a protocol that provides a hybrid solution of topological and geographical routing algorithms. We demonstrate that LGF is adaptive to unstable connectivity and scalable to large networks. Our results indicate therefore that Landmark Guided Forwarding converges much faster, scales better and adapts well within a dynamic wireless Ad Hoc environment in comparison to existing solutions.

November 2005

  • November 2 - No seminar (room not available)

  • November 9 - No seminar

  • November 16 - No seminar (teaching committee)

  • November 23
    Speaker: Thomas Karagiannis (UC Riverside)
    Title: BLINC: Multilevel Traffic Classification in the Dark
    Abstract: We present a fundamentally different approach to classifying traffic flows according to the applications that generate them. In contrast to previous methods, our approach is based on observing and identifying patterns of host behavior at the transport layer. We analyze these patterns at three levels of increasing detail (i) the social, (ii) the functional and (iii) the application level. This multilevel approach of looking at traffic flow is probably the most important contribution of this work. Furthermore, our approach has two important features. First, it operates in the dark, having (a) no access to packet payload, (b) no knowledge of port numbers and (c) no additional information other than what current flow collectors provide. These restrictions respect privacy, technological and practical constraints. Second, it can be tuned to balance the accuracy of the classification versus the number of successfully classified traffic flows. We demonstrate the effectiveness of our approach on three real traces. Our results show that we are able to classify 80%- 90% of the traffic with more than 95% accuracy.

  • November 30
    Speaker: Wenjun Hu (Cambridge Computer Lab)
    Title: Practical Network Coding for Wireless Mesh Networks [pdf] [ppt]
    Abstract: In this work, we apply network coding to unicast in wireless mesh networks to improve network throughput while reducing the bandwidth requirements. Our protocol encodes and decodes packets based on distributed and local decisions, in order to reduce the number of transmissions required in forwarding. Unlike prior work on network coding which focuses on theorectical analysis, we take a systems approach and study the performance through both emulations and testbed experiments. Our protocol aims to balance the tradeoff between reliable and efficient packet delivery. Preliminary results show that the real benefit of network coding can exceed the theorectically predicted gain, due to cross-layer interactions.

December 2005

  • December 7
    Speaker: Manuel Costa - Microsoft Research, Cambridge
    Title: Vigilante: End-to-End Containment of Internet Worms
    Abstract: Worm containment must be automatic because worms can spread too fast for humans to respond. Recent work has proposed network-level techniques to automate worm containment; these techniques have limitations because there is no information about the vulnerabilities exploited by worms at the network level. We propose Vigilante, a new end-to-end approach to contain worms automatically that addresses these limitations. Vigilante relies on collaborative worm detection at end hosts, but does not require hosts to trust each other. Hosts run instrumented software to detect worms and broadcast self-certifying alerts (SCAs) upon worm detection. SCAs are proofs of vulnerability that can be inexpensively verified by any vulnerable host. When hosts receive an SCA, they generate filters that block infection by analysing the SCA-guided execution of the vulnerable software. We show that Vigilante can automatically contain fast-spreading worms that exploit unknown vulnerabilities without blocking innocuous traffic.

  • December 14 - No seminar (teaching committee)