A Computational Approach to Packet Classification

Multi-field packet classification is a crucial component in modern software-defined data center networks. To achieve high throughput and low latency, state-of-the-art algorithms strive to fit the rule lookup data structures into on-die caches; however, they do not scale well with the number of rules. We present a novel approach, NuevoMatch, which improves the memory scaling of existing methods. A new data structure, Range Query Recursive Model Index (RQ-RMI), is the key component that enables NuevoMatch to replace most of the accesses to main memory with model inference computations. We describe an efficient training algorithm that guarantees the correctness of the RQ-RMI-based classification. The use of RQ-RMI allows the rules to be compressed into model weights that fit into the hardware cache. Further, it takes advantage of the growing support for fast neural network processing in modern CPUs, such as wide vector instructions, achieving a rate of tens of nanoseconds per lookup. Our evaluation using 500K multi-field rules from the standard ClassBench benchmark shows a geometric mean compression factor of 4.9x, 8x, and 82x, and average performance improvement of 2.4x, 2.6x, and 1.6x in throughput compared to CutSplit, NeuroCuts, and TupleMerge, all state-of-the-art algorithms.Comment: To appear in SIGCOMM 202

AS-Path Prepending: There is no rose without a thorn

Inbound traffic engineering (ITE) - -the process of announcing routes to, e.g., maximize revenue or minimize congestion - -is an essential task for Autonomous Systems (ASes). AS Path Prepending (ASPP) is an easy to use and well-known ITE technique that routing manuals show as one of the first alternatives to influence other ASes' routing decisions. We observe that origin ASes currently prepend more than 25% of all IPv4 prefixes. ASPP consists of inflating the BGP AS path. Since the length of the AS path is the second tie-breaker in the BGP best path selection, ASPP can steer traffic to other routes. Despite being simple and easy to use, the appreciation of ASPP among operators and researchers is diverse. Some have questioned its need, effectiveness, and predictability, as well as voiced security concerns. Motivated by these mixed views, we revisit ASPP. Our longitudinal study shows that ASes widely deploy ASPP, and its utilization has slightly increased despite public statements against it. We surprisingly spot roughly 6k ASes originating at least one prefix with prepends that achieve no ITE goal. With active measurements, we show that ASPP effectiveness as an ITE tool depends on the AS location and the number of available upstreams; that ASPP security implications are practical; identify that more than 18% of the prepended prefixes contain unnecessary prepends that achieve no apparent goal other than amplifying existing routing security risks. We validate our findings in interviews with 20 network operators

Effects of early feeding on growth velocity and overweight/obesity in a cohort of HIV unexposed South African infants and children

BACKGROUND: South Africa has the highest prevalence of overweight/obesity in Sub-Saharan Africa. Assessing the effect of modifiable factors such as early infant feeding on growth velocity and overweight/obesity is therefore important. This paper aimed to assess the effect of infant feeding in the transitional period (12 weeks) on 12–24 week growth velocity amongst HIV unexposed children using WHO growth velocity standards and on the age and sex adjusted body mass index (BMI) Z-score distribution at 2 years. METHODS: Data were from 3 sites in South Africa participating in the PROMISE-EBF trial. We calculated growth velocity Z-scores using the WHO growth standards and assessed feeding practices using 24-hour and 7-day recall data. We used quantile regression to study the associations between 12 week infant feeding and 12–24 week weight velocity (WVZ) with BMI-for-age Z-score at 2 years. We included the internal sample quantiles (70th and 90th centiles) that approximated the reference cut-offs of +2 (corresponding to overweight) and +3 (corresponding to obesity) of the 2 year BMI-for-age Z-scores. RESULTS: At the 2-year visit, 641 children were analysed (median age 22 months, IQR: 17–26 months). Thirty percent were overweight while 8.7% were obese. Children not breastfed at 12 weeks had higher 12–24 week mean WVZ and were more overweight and obese at 2 years. In the quantile regression, children not breastfed at 12 weeks had a 0.37 (95% CI 0.07, 0.66) increment in BMI-for-age Z-score at the 50th sample quantile compared to breast-fed children. This difference in BMI-for-age Z-score increased to 0.46 (95% CI 0.18, 0.74) at the 70th quantile and 0.68 (95% CI 0.41, 0.94) at the 90th quantile . The 12–24 week WVZ had a uniform independent effect across the same quantiles. CONCLUSIONS: This study demonstrates that the first 6 months of life is a critical period in the development of childhood overweight and obesity. Interventions targeted at modifiable factors such as early infant feeding practices may reduce the risks of rapid weight gain and subsequent childhood overweight/obesity.Scopu

UGR’16: A New Dataset for the Evaluation of Cyclostationarity-Based Network IDSs

The evaluation of algorithms and techniques to implement intrusion detection systems heavily rely on the existence of well designed datasets. In the last years, a lot of efforts have been done towards building these datasets. Yet, there is still room to improve. In this paper, a comprehensive review of existing datasets is first done, making emphasis on their main shortcomings. Then, we present a new dataset that is built with real traffic and up-to-date attacks. The main advantage of this dataset over previous ones is its usefulness for evaluating IDSs that consider long-term evolution and traffic periodicity. Models that consider differences in daytime/night or weekdays/weekends can also be trained and evaluated with it. We discuss all the requirements for a modern IDS evaluation dataset and analyze how the one presented here meets the different needs

Growth and nutritional status of formula-fed infants aged 2-10 weeks in the Prevention of Mother-to-Child Transmission (PMTCT) Programme at the Dr George Mukhari Hospital, Gauteng, South Africa

Thesis (MNutr (Interdisciplinary Health Sciences. Human Nutrition))--Stellenbosch University, 2008.INTRODUCTION: Since the start of the Prevention of Mother-to-Child Transmission (PMTCT) Programme at Dr George Mukhari Hospital in 2001, there has been no evaluation of the effect of formula feeding on the growth and dietary intakes of enrolled infants. AIM: The aim of this study was to determine the short-term growth, anthropometry and dietary intake of infants from two to ten weeks of age were entered into the PMTCT Programme at the Department of Human Nutrition at Dr George Mukhari Hospital from two to ten weeks of age. METHODS: This was a descriptive, longitudinal (eight weeks duration) study. Anthropometric assessment including length and head circumference was performed at two weeks of age and thereafter at ten weeks of age. Weight measurement was performed at age two weeks (visit 1), six weeks (visit 2) and ten weeks (visit 3). Anthropometric measurements were compared with CDC 20003 growth charts. Feeding practices and dietary intake (24 hour diet recall interview) were assessed at each of the four week interval visits and evaluated according to the DRIs59. At the third visit, a socio-demographic interview and a usual food intake interview were performed. RESULTS: A total of 151 [male (N = 75) and female (N = 76)] infants completed the study. A total of 110 (72%) mothers resided in the Soshanguve area and 138 (91%) of the mothers had attended high school. The majority (75%) of mothers was not generating an income from employment. Generally, mothers had access to safe drinking water and all (99%) but two mothers used pre-boiled water before preparing infant formula. The accuracy and correctness of reconstituting infant formula decreased with each visit as feeds were increasingly made too dilute. A total of 124 (82%) infants were exclusively formula fed. The remainder received water, water with sugar and/or complementary feeds. Mean energy and macronutrient intakes of both males (N = 65, 87%) and females (N = 61, 80%) were below recommendations at age two weeks. Of all the macronutrients, fats were consumed the least by both males (N = 67, 89%) and females (N = 66, 87%) at visit 1. Catch up growth was evident and nutrient intakes improved as the study progressed. The mean weight gain of all infants from visit 1 to 2 was 1.2 (SD 0.3) kg and 0.9 (SD 0.3) kg from visit 2 to 3 (exceeding the CDC 20003 recommendation for both male and female infants). The incidence of underweight, wasting and head circumference-for-age below the third percentile decreased from visit 1 to 3, but the number of stunted infants increased towards visit 3. The majority of infants in this study grew well in their first ten weeks of life. Growth accelerated as infants became older and growth faltering improved by ten weeks of age. CONCLUSION: Overall, the growth of the infants referred to the PMTCT Programme at the Department of Human Nutrition at Dr George Mukhari Hospital would appear to be adequate but mothers’ approach to formula feeding practices needs to be improved in some aspects of feeding their infants

claffy, k.: AS relationships, customer cones, and validation

ABSTRACT Business relationships between ASes in the Internet are typically confidential, yet knowledge of them is essential to understand many aspects of Internet structure, performance, dynamics, and evolution. We present a new algorithm to infer these relationships using BGP paths. Unlike previous approaches, our algorithm does not assume the presence (or seek to maximize the number) of valley-free paths, instead relying on three assumptions about the Internet's inter-domain structure: (1) an AS enters into a provider relationship to become globally reachable; and (2) there exists a peering clique of ASes at the top of the hierarchy, and (3) there is no cycle of p2c links. We assemble the largest source of validation data for AS-relationship inferences to date, validating 34.6% of our 126,082 c2p and p2p inferences to be 99.6% and 98.7% accurate, respectively. Using these inferred relationships, we evaluate three algorithms for inferring each AS's customer cone, defined as the set of ASes an AS can reach using customer links. We demonstrate the utility of our algorithms for studying the rise and fall of large transit providers over the last fifteen years, including recent claims about the flattening of the AS-level topology and the decreasing influence of "tier-1" ASes on the global Internet

The COMMONS Initiative: Cooperative Measurement and Modeling of Open Networked Systems

workshop to discuss and ultimately propose a collaboration among researchers and networks to simultaneously solve three acute and growing problems facing the Internet: a self-reported financial crisis in the Internet infrastructure provider industry that poses a severe threat to broadband growth and U.S. competitiveness; a data acquisition crisis which has deeply stunted the field of network science; and a dilemma within emerging community, municipal, regional, and state networks, who need (additional) broadband connectivity but face severely limited provider, service level, and usage options. The Cooperative Measurement and Modeling of Open Networked Systems (COMMONS) initiative proposes to build or partner with a collaborative national backbone to connect participating community, municipal, regional, and state networks to one another and to the global Internet. COMMONS Peering will be conditionally available to city, county, state, and federal government entities, academic institutions, community Internet initiatives (e.g., community wireless networks), and commercial entities based upon the following three conditions: (1) networks will make select operational data available to COMMONS researchers (under appropriate legal data sharing and privacy guards); (2) the attached networks must agree to develop and abide by COMMONS policies which will be based upon research results of empirical data analyses of network usage; and, (3) participating networks must abid

The 2nd Workshop on Active Internet Measurements (AIMS-2) Report

On February 8-10, 2010, CAIDA hosted the second Work- shop on Active Internet Measurements (AIMS-2) as part of our series of Internet Statistics and Metrics Analysis (ISMA) workshops. The goals of this workshop were to further our understanding of the potential and limitations of active mea- surement research and infrastructure in the wide-area Inter- net, and to promote cooperative solutions and coordinated strategies to addressing future data needs of the network and security research communities. The three-day workshop included presentations, group discussion and analysis, and focused interaction between participating researchers, oper- ators, and policymakers from all over the world. This report describes the motivation and findings of the workshop, and reviews progress on recommendations developed at the 1st Active Internet Measurements Workshop in 2009 [18]. Slides from the workshop presentations are available at [9]