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Talk: Sharon Goldberg Thurs 9/19 4:30pm
by Nicole E. Wagenblast 19 Sep '13

19 Sep '13

Should we secure routing with the RPKI Sharon Goldberg , Boston University Thursday, September 19, 4:30-5:30pm Computer Science, 402 In this talk I will overview the benefits and risks of adopting the Resource Public Key Infrastructure (RPKI), a new centralized security infrastructure for interdomain routing that has recently been standardized by the IETF. On one hand, I argue that the RPKI is one of the most effective ways to limit attacks on interdomain routing; more so, in fact, than more advanced cryptographic solutions that require more drastic changes to router hardware and protocol messages. On the other hand, I discuss how state-sponsored actors and malicious attackers can exploit the RPKI's centralized architecture to launch new attacks that can cause serious harm to the Internet's routing system. I conclude by discussing open problems that should be solved before the RPKI is widely adopted. Based on works with Robert Lychev, Pete Hummon, Jennifer Rexford, and Michael Schapira that appeared at SIGCOMM'10 and SIGCOMM'13, and work in progress with Kyle Brogle, Danny Cooper, Ethan Heilman, and Leonid Reyzin. Sharon Goldberg is an Assistant Professor in the Department of Computer Science at Boston University. Her research focuses on finding practical solutions to problems in network security. She received her Ph.D. from Princeton University in 2009, her B.A.Sc. from the University of Toronto in 2003, and has worked as a researcher at IBM, Cisco, and Microsoft, and a telecommunication engineer at Bell Canada and Hydro One Networks.

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Thurs 9/19 12pm Talk: Younghwan Go, Gaining Control of Cellular Traffic Accounting by Spurious TCP Retransmission
by Nicole E. Wagenblast 19 Sep '13

19 Sep '13

Gaining Control of Cellular Traffic Accounting by Spurious TCP Retransmission Younghwan Go , Korea Advanced Institute of Science and Technology Thursday, September 19, 12pm Computer Science 402 Packet retransmission is a fundamental TCP feature that ensures reliable data transfer between two end nodes. Interestingly, when it comes to cellular data accounting, TCP retransmission creates an important policy issue. Cellular ISPs might argue that all retransmitted IP packets should be accounted for billing since they consume the resources of their infrastructures. On the other hand, the service subscribers might want to pay only for the application data by taking out the amount for retransmission. Regardless of the policies, however, we find that TCP retransmission can be easily abused to manipulate the current practice of cellular traffic accounting. In this work, we investigate the TCP retransmission accounting policies of 12 cellular ISPs in the world and report the accounting vulnerabilities with TCP retransmission attacks. First, we find that cellular data accounting policies vary from ISP to ISP. While the majority of cellular ISPs blindly account for every IP packet, some ISPs intentionally remove the retransmission packets from the user bill for fairness. Second, we show that it is easy to launch the “usage-inflation” attack on the ISPs that blindly account for every IP packet. In our experiments, we could inflate the usage up to the monthly limit only within 9 minutes of the attack completely without the knowledge of the subscriber. For those ISPs that do not account for retransmission, we successfully launch the “free-riding” attack by tunneling the payload under fake TCP headers that look like retransmission. To counter the attacks, we argue that the ISPs should consider ignoring TCP retransmission for billing while detecting the tunneling attacks by deep packet inspection. We implement and evaluate Abacus, a light-weight accounting system that reliably detects “free-riding” attacks even in the 10 Gbps links. Younghwan Go is currently a Ph.D. student at KAIST. His research interests are networked and distributed systems, network security and mobile network. He received a M.S. degree in Electrical Engineering and Information Security from KAIST in 2013. Previously, he received a Bachelor's degree in Electrical Engineering from KAIST in 2011. Nicole Wagenblast Computer Science Department Princeton University 35 Olden Street Princeton, NJ 08540 609-258-4624

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Colloquium Speaker Yoram Moses
by Nicole E. Wagenblast 06 Sep '13

06 Sep '13

The Knowledge of Preconditions principle Yoram Moses , Technion Monday, September 9, 4:30pm Computer Science 105 This talk will present a simple principle relating knowledge and action in distributed systems: If some condition must be true when a given action is taken, then this condition must be known when the action is taken. This yields a number of fundamental connections between knowledge and multi-party coordination. In particular, the talk will illustrate how these can provide insight into the interplay between time, communication and coordination in networks and distributed systems. The talk will be self-contained, intended for a general CS audience. The latter part of the talk is based on joint work with Ido Ben Zvi. No familiarity with the subject will be assumed. Yoram Moses is the Israel Pollack Academic Chair at the Technion. He is a recipient of the Godel Prize 1997 and the Dijkstra Award in 2009.

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J Farnham FPO
by Melissa M. Lawson 27 Aug '13

27 Aug '13

Jsees Farnham will present his FPO on Wednesday September 4 at 3PM in Room 402. The members of his committee are: Mona Singh, advisor; Olga Troyanskaya and Andrea LaPaugh, readers; Vivek Pai and Tom Funkhouser, nonreaders. A copy of his thesis, "Organization and function acquisition in protein-protein interaction networks", is on display in Room 310. Everyone is invited to attend his talk.

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S Sachdeva FPO
by Melissa M. Lawson 06 Aug '13

06 Aug '13

Sushant Sachdeva will present his FPO on Sunday August 11 at 12:30 PM in Room 402. NOTE DAY! The members of his committee are: Sanjeev Arora, advisor; Moses Charikar and Nisheeth Vishnoi (MSR India), readers; Bernard Chazelle and Mark Braverman, nonreaders. A copy of his thesis, "New Results in the Theory of Approximation: Fast Graph Algorithms and Inapproximability", is on display in Room 310. Everyone is invited to attend his talk.

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11am Tue Aug 6 talk on root causes of interdomain path changes
by Jennifer Rexford 05 Aug '13

05 Aug '13

Speaker: Umar Javed, University of Washington Title: PoiRoot: Investigating the Root Cause of Interdomain Path Changes Date/time: 11am-noon Tue Aug 6 Location: CS 402 Abstract: Interdomain path changes occur frequently. Because routing protocols expose insufficient information to reason about all changes, the general problem of identifying the root cause remains unsolved. In this work, we design and evaluate PoiRoot, a real-time system that allows a provider to accurately isolate the root cause (the network responsible) of path changes affecting its prefixes. First, we develop a new model describing path changes and use it to provably identify the set of all potentially responsible networks. Next, we develop a recursive algorithm that accurately isolates the root cause of any path change. We observe that the algorithm requires monitoring paths that are generally not visible using standard measurement tools. To address this limitation, we combine existing measurement tools in new ways to acquire path information required for isolating the root cause of a path change. We evaluate PoiRoot on path changes obtained through controlled Internet experiments, simulations, and "in the wild" measurements. We demonstrate that Poi- Root is highly accurate, works well even with partial information, and generally narrows down the root cause to a single network or two neighboring ones. On controlled experiments PoiRoot is 100% accurate, as opposed to prior work which is accurate only 61.7% of the time.

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P Jiang FPO
by Melissa M. Lawson 30 Jul '13

30 Jul '13

Peng Jiang will present his FPO on Monday August 5 at 11 AM in 101 Carl Icahn (Note Location!). The members of his committee are: Mona Singh, advisor; Olga Troyanskaya and Hilary Coller, readers; Gertrud Schupbach and John Storey, nonreaders. A copy of his thesis, "Combinatorial code analysis for understanding biological regulation", is on display in Room 310. Everyone is invited to attend his talk.

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3:30pm Wed Jul 24 talk on cellular networks by Erran Li (Bell Labs) in CS 402
by Jennifer Rexford 24 Jul '13

24 Jul '13

Speaker: Dr. Erran Li, Bell Labs Title: Making Cellular Networks Scalable and Flexible through Design-in-the-Large Date/time: 3:30-4:30pm Wednesday July 24 Location: 402 in the CS building Abstract: The rapid penetration of smart phones has put tremendous stress on cellular data networks. To understand the fundamental limitations of current cellular network architecture, I will first summarize my work on scalable network monitoring primitives and root cause analysis of performance problems. This work became a key part of the Alcatel-Lucent Wireless Network Guardian 9900 product. Our measurement study reveals that our mobile user experiences are hampered by the lack of access bandwidth at radio access networks and the inflexibility of cellular core networks. I will then address the two key problems through the principle of design-in-the-large. (1) To scale access bandwidth at radio access networks, I will present the design and prototype of Argos, a base station architecture that employs an unprecedented number of antennas simultaneously to serve a smaller number of mobile devices in the same band of frequencies. Both analysis and early experimental results suggest this design can lead to orders of magnitude increase in both spectral and energy efficiency. (2) To enable flexible provisioning of fine-grained policies at cellular core networks, I will summarize the design and prototype of SoftCell, a scalable software-defined cellular core network architecture. SoftCell achieves scalability through asymmetric edge design and selective multi-dimensional aggregation in the data plane and switch offloading in the control plane. Evaluations based on real LTE network traces show that a SoftCell controller can handle a network of thousands of base stations. This is joint work with collaborators at Princeton, Rice, Yale, and Bell Labs.

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Re: [talks] 2pm Thu Jul 25 data center networking talk by Kyriakos Zarifis (USC) in CS 402
by Srinivas Narayana 23 Jul '13

23 Jul '13

Speaker: Kyriakos Zarifis, University of Southern California (USC) Title: Don't Drop, Detour! Date/time: 2-2.30pm, Thursday July 25 Location: 402 in the CS building Abstract: Today's data centers must support a range of workloads with different demands. While existing approaches handle routine traffic smoothly, ephemeral but intense hotspots cause excessive packet loss and severely degrade performance. This loss occurs even though the congestion is typically highly localized, with spare buffer capacity available at nearby switches. In this talk, we argue that switches should share buffer capacity to effectively handle this spot congestion without the latency or monetary hit of deploying large buffers at individual switches. Specifically, we present DIBS, a mechanism that achieves a near lossless network without requiring additional buffers. Using DIBS, a congested switch detours excess packets to neighboring switches to avoid dropping them. We implement DIBS in hardware, on software routers in a testbed, and in simulation, and we demonstrate that it reduces the 99th percentile of query completion time by 85%, with very little impact on background traffic. Speaker bio (from his webpage): Kyriakos Zarifis is a 1st year PhD student in the Networked Systems Lab at the University of Southern California. Previously he worked as a networking researcher at the International Computer Science Institute at Berkeley, where he also dedicated part of his time maintaining NOX. He holds an M.Sc. in Internetworking from Kungliga Tekniska Högskolan and a Ptychion (B.Sc.) from the Department of Informatics and Telecommunications of the University of Athens.

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3:30pm Wed Jul 24 talk on cellular networks by Erran Li (Bell Labs) in CS 402
by Jennifer Rexford 17 Jul '13

17 Jul '13

Speaker: Dr. Erran Li, Bell Labs Title: Making Cellular Networks Scalable and Flexible through Design-in-the-Large Date/time: 3:30-4:30pm Wednesday July 24 Location: 402 in the CS building Abstract: The rapid penetration of smart phones has put tremendous stress on cellular data networks. To understand the fundamental limitations of current cellular network architecture, I will first summarize my work on scalable network monitoring primitives and root cause analysis of performance problems. This work became a key part of the Alcatel-Lucent Wireless Network Guardian 9900 product. Our measurement study reveals that our mobile user experiences are hampered by the lack of access bandwidth at radio access networks and the inflexibility of cellular core networks. I will then address the two key problems through the principle of design-in-the-large. (1) To scale access bandwidth at radio access networks, I will present the design and prototype of Argos, a base station architecture that employs an unprecedented number of antennas simultaneously to serve a smaller number of mobile devices in the same band of frequencies. Both analysis and early experimental results suggest this design can lead to orders of magnitude increase in both spectral and energy efficiency. (2) To enable flexible provisioning of fine-grained policies at cellular core networks, I will summarize the design and prototype of SoftCell, a scalable software-defined cellular core network architecture. SoftCell achieves scalability through asymmetric edge design and selective multi-dimensional aggregation in the data plane and switch offloading in the control plane. Evaluations based on real LTE network traces show that a SoftCell controller can handle a network of thousands of base stations. This is joint work with collaborators at Princeton, Rice, Yale, and Bell Labs.

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