CCR Papers from July 2010

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  • S. Keshav

    Every scientific discipline builds on the past: new ideas invariably appear from the analysis, synthesis, and repudiation of prior work. Even an innovator like Sir Isaac Newton wrote to Robert Hooke on 15 February 1676: “If I have seen further it is only by standing on the shoulders of giants.” A necessary prerequisite for building on the past is for the body of archival work to be of the highest possible quality. Work that enters the communal memory should have no errors that either that the authors are aware of, or that can be rectified by careful peer review. Of course, no process can hope to eliminate errors altogether, but archival work should be free from errors that can be avoided with reasonable care.

    Conference publications, by their very nature, are susceptible to errors. The process is driven by strict deadlines, preventing authors from having a back-and-forth exchange with the reviewers in an attempt to fix problems. Program committee members, faced with a stack of 15 to 25 papers to review, naturally limit the depth of their reviews. Moreover, the selection of a paper for publication means only that a paper ranked amongst the best of those submitted for consideration by the program committee, rather than a guarantee of absolute quality. Although shepherding does improve the quality of an accepted paper, even shepherding is only mildly effective when faced with the natural reluctance of authors to do additional work for a paper that has already been accepted for publication. For these reasons, a field that treats conferences as archival publications is building on a foundation of sand.

    The Computer Research Association (CRA), however, arguing on behalf of the entire field of computer science, states that: “The reason conference publication is preferred to journal publication, at least for experimentalists, is the shorter time to print (7 months vs 1-2 years), the opportunity to describe the work before one’s peers at a public presentation, and the more complete level of review (4-5 evaluations per paper compared to 2-3 for an archival journal) [Academic Careers, 94]. Publication in the prestige conferences is inferior to the prestige journals only in having significant page limitations and little time to polish the paper. In those dimensions that count most, conferences are superior.” [1]

    The two negatives for conferences identified by the CRA, page limits and ‘lack of polish’ are worth examining. Today, the IEEE/ACM Transactions on Networking (ToN) limits papers to ten free pages and a maximum of 14 pages [2]. This is scarcely longer than many conference papers. Thus, the situation for journal papers is even worse than what the CRA states. On the other hand, what the CRA dismissively calls a ‘lack of polish’ sweeps many issues under the metaphorical carpet: issues like inadequate experimental design, lack of rigour in statistical analysis, and incorrect proofs. It seems unwise to permit these severe problems in papers that we admit to archival status. Unfortunately, given the conference publication process, these errors are unavoidable. Perhaps it would be better to think of ways of improving the journal publication process instead.

    Let's start by considering the reasons why the CRA thinks conference publications are superior to journal publications. Two of the three reasons – number of reviews and time to publication – are easily remedied. There is no reason why journal editors could not ask for more reviews. Few conference papers receive more than three reviews and this number could be easily matched by journal editors. Second, the two-to-three year publication delay for a journal paper, according to Henning Schulzrinne, who has had a long history of dealing with this process at ToN, arises primarily from the delay in assigning papers to reviewers and the delay in the authors’ responses to the first round of reviewer comments. The equivalent processes at conferences take only a few weeks. Why can’t journals match that? As a contrasting data point, journals in civil engineering have review times of 90 days and publication delays of only three to five months [3], which is shorter than even conference publication delays in computer science.

    This leaves conferences with just one advantage over journals, that of permitting face-to-face meetings. Specifically, in his recent article in CACM [3], Lance Fortnow argues that conferences allow the community:
    * To rate publications and researchers.
    * To disseminate new research results and ideas.
    * To network, gossip, and recruit.
    * To discuss controversial issues in the community.

    These are tangible and valuable benefits. However, as Fortnow and others have argued, we could organize conferences where not all accepted papers are presented on stage, leaving some to be presented in the form of posters. These would result in better-attended, more inclusive conferences, which would meet the needs Fortnow identifies, while not detracting from the archival value of journals. The informal poster format would also allow the presentation of early-stage ideas, which is valuable both to authors and to the research community. If posters are clearly marked, this would not detract from the prestige of full papers already published in the conference.

    I believe that we can begin to restore the integrity of archival publications by taking the following steps. First, we should increase the number and perceived prestige of posters at SIGCOMM-sponsored conferences, with more time set aside in the technical program for attendees to view posters. This would boost conference participation and better disseminate early stage ideas. Second, we should re-engineer the journal publication process to cap publication delay to six months. Third, journal editors should allow papers to be as lengthy as they need to be, instead of imposing an artificial page limit. Fourth, a greater emphasis on journal publications will be possible only if journals themselves are economically viable. If it turns out that print journals are unviable (a debatable point), we should consider moving to electronic-only journals or subsidize the production cost from conference fees.

    As these changes are made, other synergies may also present themselves. For example, reducing the conference review load could free up resources for journal reviews. Similarly, increased conference attendance from a more generous poster acceptance policy could increase journal subsidies, and moving to electronic journals would not only reduce costs, but would also cut publication delay.

    The net result of these changes will be to restore the integrity of our archival work. We cannot afford to let this slip much longer: the time to act is now!

    [1] D. Patterson, J. Snyder, J. Ullman, Evaluating computer scientists and engineers for promotion and tenure; http://www.cra.org/reports/tenure_review.html, August 1999.
    [2] http://www.ton.seas.upenn.edu/submissions.html#format
    [3] http://pubs.asce.org/editors/journal/resourceeditor/editorresponsibiliti...
    [4] Lance Fortnow, Viewpoint: Time for computer science to grow up, Communications of the ACM. Vol. 52 No. 8, Pages 33-35.

  • Sardar Ali, Irfan Ul Haq, Sajjad Rizvi, Naurin Rasheed, Unum Sarfraz, Syed Ali Khayam, and Fauzan Mirza

    Real-time Anomaly Detection Systems (ADSs) use packet sampling to realize tra±c analysis at wire speeds. While recent studies have shown that a considerable loss of anomaly detection accuracy is incurred due to sampling, solutions to mitigate this loss are largely unexplored. In this paper, we propose a Progressive Security-Aware Packet Sampling (PSAS) algorithm which enables a real-time inline anomaly detector to achieve higher accuracy by sampling larger volumes of malicious tra±c than random sampling, while adhering to a given sampling budget. High malicious sampling rates are achieved by deploying inline ADSs progressively on a packet's path. Each ADS encodes a binary score (malicious or benign) of a sampled packet into the packet before forwarding it to the next hop node. The next hop node then samples packets marked as malicious with a higher probability. We analytically prove that under certain realistic conditions, irrespective of the intrusion detection algorithm used to formulate the packet score, PSAS always provides higher malicious packet sampling rates. To empirically evaluate the proposed PSAS algorithm, we simultaneously collect an Internet tra±c dataset containing DoS and portscan attacks at three di®erent deployment points in our university's network. Experimental results using four existing anomaly detectors show that PSAS, while having no extra communication overhead and extremely low complexity, allows these detectors to achieve signi¯cantly higher accuracies than those operating on random packet samples.

    R. Teixeira
  • Roch Guérin and Kartik Hosanagar

    Although IPv6 has been the next generation Internet protocol for nearly 15 years, new evidences indicate that transitioning from IPv4 to IPv6 is about to become a more pressing issue. This paper attempts to quantify if and how such a transition may unfold. The focus is on “connectivity quality,” e.g., as measured by users’ experience when accessing content, as a possible incentive (or disincentive) for migrating to IPv6, and on “translation costs” (between IPv6 and IPv4) that Internet Service Providers will incur during this transition. The paper develops a simple model that captures some of the underlying interactions, and highlights the ambiguous role of translation gateways that can either help or discourage IPv6 adoption. The paper is an initial foray in the complex and often puzzling issue of migrating the current Internet to a new version with which it is incompatible.

    S. Saroiu
  • Nandita Dukkipati, Tiziana Refice, Yuchung Cheng, Jerry Chu, Tom Herbert, Amit Agarwal, Arvind Jain, and Natalia Sutin

    TCP flows start with an initial congestion window of at most four segments or approximately 4KB of data. Because most Web transactions are short-lived, the initial congestion window is a critical TCP parameter in determining how quickly flows can finish. While the global network access speeds increased dramatically on average in the past decade, the standard value of TCP’s initial congestion window has remained unchanged.

    In this paper, we propose to increase TCP’s initial congestion window to at least ten segments (about 15KB). Through large-scale Internet experiments, we quantify the latency benefits and costs of using a larger window, as functions of network bandwidth, round-trip time (RTT), bandwidthdelay product (BDP), and nature of applications. We show that the average latency of HTTP responses improved by approximately 10% with the largest benefits being demonstrated in high RTT and BDP networks. The latency of low bandwidth networks also improved by a significant amount in our experiments. The average retransmission rate increased by a modest 0.5%, with most of the increase coming from applications that effectively circumvent TCP’s slow start algorithm by using multiple concurrent connections. Based on the results from our experiments, we believe the initial congestion window should be at least ten segments and the same be investigated for standardization by the IETF.

    Y. Zhang
  • Zuoning Yin, Matthew Caesar, and Yuanyuan Zhou

    Software errors and vulnerabilities in core Internet routers have led to several high-profile attacks on the Internet infrastructure and numerous outages. Building an understanding of bugs in open-source router software is a first step towards addressing these problems. In this paper, we study router bugs found in two widely-used open-source router implementations. We evaluate the root cause of bugs, ease of diagnosis and detectability, ease of prevention and avoidance, and their effect on network behavior.

    S. Saroiu
  • Michael Buettner and David Wetherall

    We have developed a low cost software radio based platform for monitoring EPC Gen 2 RFID traffic. The Gen 2 standard allows for a range of PHY layer configurations and does not specify exactly how to compose protocol messages to inventory tags. This has made it difficult to know how well the standard works, and how it is implemented in practice. Our platform provides much needed visibility into Gen 2 systems by capturing reader transmissions using the USRP2 and decoding them in real-time using software we have developed and released to the public. In essence, our platform delivers much of the functionality of expensive (> $50,000) conformance testing products, with greater extensibility at a small fraction of the cost. In this paper, we present the design and implementation of the platform and evaluate its effectiveness, showing that it has better than 99% accuracy up to 3 meters. We then use the platform to study a commercial RFID reader, showing how the Gen 2 standard is realized, and indicate avenues for research at both the PHY and MAC layers.

    A. Chaintreau
  • Jon Crowcroft

    I’m so Bored of the Future Internet (FI). There are so many initiatives to look at the Internet’s Future1, anyone would think that there was some tremendous threat like global warming, about to bring about its immediate demise, and that this would bring civilisation crashing down around our ears.

    The Internet has a great future behind it, of course. However, my thesis is that the Future Internet is about as relevant as Anthropogenic Global Warming (AGW), in the way it is being used to support various inappropriate activities. Remember that the start of all this was not the exhaustion of IPv4 address space, or the incredibly slow convergence time of BGP routes, or the problem of scaling router memory for FIBs. It was the US research community reacting to a minor (as in parochial) temporary problem of funding in Communications due to slow down within NSF and differing agendas within DARPA.

    It is not necessary to invoke all the hype and hysteria - it is both necessary and sufficient to talk about sustainable energy2, and good technical communications research, development, deployment and operations.

    To continue the analogy between FI and AGW, what we really do not need is yet more climatologists with dodgy data curation methodologies (or ethnographers studying Internet governance).

    What we do need is some solid engineering, to address a number of problems the Internet has. However, this is in fact happening, and would not stop happening if the entire Future Internet flagship was kidnapped by aliens.
    “We don’t need no” government agency doing top down dictats about what to do when. It won’t work and it will be a massive waste of time, energy and other resources - i.e. like AGW, it will be a load of hot air:)

    On the other hand, there are a number of deeper lessons from the Internet Architecture which might prove useful in other domains, and in the bulk of this opinion piece, I give examples of these, applying the Postel and End-to-end principles to transport, energy, government information/vices.

  • Constantine Dovrolis, Krishna Gummadi, Aleksandar Kuzmanovic, and Sascha D. Meinrath

    Measurement Lab (M-Lab) is an open, distributed server platform for researchers to deploy active Internet measurement tools. The goal of M-Lab is to advance network research and empower the public with useful information about their broadband connections. By enhancing Internet transparency, M-Lab helps sustain a healthy, innovative Internet. This article describes M-Lab’s objectives, administrative organization, software and hardware infrastructure. It also provides an overview of the currently available measurement tools and datasets, and invites the broader networking research community to participate in the project.

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