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Sonia Fahmy

Bio: Sonia Fahmy is an academic researcher from Purdue University. The author has contributed to research in topics: Asynchronous Transfer Mode & Wireless sensor network. The author has an hindex of 39, co-authored 217 publications receiving 11177 citations. Previous affiliations of Sonia Fahmy include Ohio State University & Hewlett-Packard.


Papers
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Proceedings ArticleDOI
23 Nov 2020
TL;DR: This paper presents RoCC, a robust congestion control approach for datacenter networks based on RDMA that leverages switch queue size as an input to a PI controller, which computes the fair data rate of flows in the queue, signaling it to the flow sources.
Abstract: In this paper, we present RoCC, a robust congestion control approach for datacenter networks based on RDMA. RoCC leverages switch queue size as an input to a PI controller, which computes the fair data rate of flows in the queue, signaling it to the flow sources. The PI parameters are self-tuning to guarantee stability, rapid convergence, and fair and near-optimal throughput in a wide range of congestion scenarios. Our simulation and DPDK implementation results show that RoCC can achieve up to 7× reduction in PFC frames generated under high average load levels, compared to DCQCN. At the same time, RoCC can achieve up to 8× lower tail latency, compared to DCQCN and HPCC. We also find that RoCC does not require PFC. The functional components of RoCC are implementable in P4-based and fixed-function switch ASICs.

20 citations

Proceedings ArticleDOI
07 Oct 1998
TL;DR: In this paper, the authors give various possibilities for defining fairness for multipoint connections, and show the tradeoffs involved, and also show that ATM bandwidth allocation algorithms need to be adapted to give fair allocations for multippoint-to-point connections.
Abstract: In multipoint-to-point connections, the traffic at the root is the combination of all traffic originating at the leaves. A crucial concern in the case of multiple senders is how to define fairness within a multicast group, and among groups and point-to-point connections. Fairness definition can be complicated since the multipoint connection can have the same identifier on each link, and senders might not be distinguishable in this case. Many rate allocation algorithms implicitly assume that there is only one sender in each VC, which does not hold for multipoint-to-point cases. We give various possibilities for defining fairness for multipoint connections, and show the tradeoffs involved. In addition, we show that ATM bandwidth allocation algorithms need to be adapted to give fair allocations for multipoint-to-point connections.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

19 citations

Proceedings ArticleDOI
14 Apr 2013
TL;DR: This work proposes a new system, Pegasus, to leverage commercially available co-located compute and storage devices near routers and switches and adaptively manages data transfers between monitors and aggregators based on traffic patterns and user queries.
Abstract: Accurate online network monitoring is crucial for detecting attacks, faults, and anomalies, and determining traffic properties across the network. With high bandwidth links and consequently increasing traffic volumes, it is difficult to collect and analyze detailed flow records in an online manner. Traditional solutions that decouple data collection from analysis resort to sampling and sketching to handle large monitoring traffic volumes. We propose a new system, Pegasus, to leverage commercially available co-located compute and storage devices near routers and switches. Pegasus adaptively manages data transfers between monitors and aggregators based on traffic patterns and user queries. We use Pegasus to detect global icebergs or global heavy-hitters. Icebergs are flows with a common property that contribute a significant fraction of network traffic. For example, DDoS attack detection is an iceberg detection problem with a common destination IP. Other applications include identification of “top talkers,” top destinations, and detection of worms and port scans. Experiments with Abilene traces, sFlow traces from an enterprise network, and deployment of Pegasus as a live monitoring service on PlanetLab show that our system is accurate and scales well with increasing traffic and number of monitors.

19 citations

22 May 2013
TL;DR: This work proposes a multi-level framework for analyzing Internet topologies and their evolution, and develops a taxonomy of topology generators, and identifies key challenges in topology modeling.
Abstract: The topology of a network (connectivity of autonomous systems (ASes) or routers) has significant implications on the design of protocols and applications, and on the placement of services and data centers. Researchers and practitioners alike need realistic topologies for their simulation, emulation, and testbed experiments. In this work, we propose a multi-level framework for analyzing Internet topologies and their evolution. Our multi-level framework includes novel measures, evaluation strategies, and techniques for automatically learning a representative set of graph measures. We apply our framework to analyze topologies from two recent topology generators, Orbis and WIT, according to how well they achieve their advertised objectives. The generated topologies are compared to a set of benchmark datasets that approximate different views of the Internet in the data (trace-route measurements), control (BGP), and management (WHOIS) planes. Our results demonstrate key limitations of popular generators, and show that the recent Internet clustering coefficient and average distance are not time-invariant as assumed by many models. Additionally, we develop a taxonomy of topology generators, and identify key challenges in topology modeling.

18 citations

Proceedings ArticleDOI
07 Aug 2002
TL;DR: This work investigates the effect of TCP explicit congestion notification (ECN) with a new response strategy that is more aggressive in the short term, but preserves TCP long term behavior, without modifying the router marking rate.
Abstract: We investigate the effect of TCP explicit congestion notification (ECN) with a new response strategy that is more aggressive in the short term, but preserves TCP long term behavior, without modifying the router marking rate A less aggressive ECN decrease gives more incentives for end systems to become ECN-compliant, as ECN serves as an early warning sign in this case Our analysis and simulation results demonstrate the effectiveness of the new algorithm in improving throughput and reducing fluctuations We model a multiple bottleneck scenario with various types of traffic, and evaluate the effect of a number of parameters, including TCP flavor, increase/decrease parameters, buffer size, and random early detection (RED) parameters

18 citations


Cited by
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01 Jan 2002

9,314 citations

Journal ArticleDOI
TL;DR: It is proved that, with appropriate bounds on node density and intracluster and intercluster transmission ranges, HEED can asymptotically almost surely guarantee connectivity of clustered networks.
Abstract: Topology control in a sensor network balances load on sensor nodes and increases network scalability and lifetime. Clustering sensor nodes is an effective topology control approach. We propose a novel distributed clustering approach for long-lived ad hoc sensor networks. Our proposed approach does not make any assumptions about the presence of infrastructure or about node capabilities, other than the availability of multiple power levels in sensor nodes. We present a protocol, HEED (Hybrid Energy-Efficient Distributed clustering), that periodically selects cluster heads according to a hybrid of the node residual energy and a secondary parameter, such as node proximity to its neighbors or node degree. HEED terminates in O(1) iterations, incurs low message overhead, and achieves fairly uniform cluster head distribution across the network. We prove that, with appropriate bounds on node density and intracluster and intercluster transmission ranges, HEED can asymptotically almost surely guarantee connectivity of clustered networks. Simulation results demonstrate that our proposed approach is effective in prolonging the network lifetime and supporting scalable data aggregation.

4,889 citations

Journal ArticleDOI
TL;DR: A taxonomy and general classification of published clustering schemes for WSNs is presented, highlighting their objectives, features, complexity, etc and comparing of these clustering algorithms based on metrics such as convergence rate, cluster stability, cluster overlapping, location-awareness and support for node mobility.

2,283 citations

Book
12 Aug 2005
TL;DR: In this article, the authors state several problems related to topology control in wireless ad hoc and sensor networks, and survey state-of-the-art solutions which have been proposed to tackle them.
Abstract: Topology Control (TC) is one of the most important techniques used in wireless ad hoc and sensor networks to reduce energy consumption (which is essential to extend the network operational time) and radio interference (with a positive effect on the network traffic carrying capacity). The goal of this technique is to control the topology of the graph representing the communication links between network nodes with the purpose of maintaining some global graph property (e.g., connectivity), while reducing energy consumption and/or interference that are strictly related to the nodes' transmitting range. In this article, we state several problems related to topology control in wireless ad hoc and sensor networks, and we survey state-of-the-art solutions which have been proposed to tackle them. We also outline several directions for further research which we hope will motivate researchers to undertake additional studies in this field.

1,367 citations