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  1. Free, publicly-accessible full text available July 1, 2023
  2. This paper describes a cloud infrastructure and virtual laboratories on P4 programmable data plane switches. P4 programmable data planes emerged as a technology that enables innovation in networking. P4 is a programming language used to describe how network packets are processed. This paper explains an entry-level training library on P4. The virtual laboratories introduce the learner to P4 and data plane concepts by providing step-by-step guides and exercises. The virtual laboratories are hosted in the Academic Cloud, a distributed platform that manages and orchestrates computing resources. Additionally, the paper describes a work in progress of P4 virtual laboratories that uses Intel Tofino switches. Lastly, the paper discusses the use of the Academic Cloud as a network testbed.
    Free, publicly-accessible full text available May 1, 2023
  3. Google published the first release of the Bottleneck Bandwidth and Round-trip Time (BBR) congestion control algorithm in 2016. Since then, BBR has gained a widespread attention due to its ability to operate efficiently in the presence of packet loss and in scenarios where routers are equipped with small buffers. These characteristics were not attainable with traditional loss-based congestion control algorithms such as CUBIC and Reno. BBRv2 is a recent congestion control algorithm proposed as an improvement to its predecessor, BBRv1. Preliminary work suggests that BBRv2 maintains the high throughput and the bounded queueing delay properties of BBRv1. However, the literature has been missing an evaluation of BBRv2 under different network conditions. This paper presents an experimental evaluation of BBRv2 Alpha (v2alpha-2019-07-28) on Mininet, considering alternative active queue management (AQM) algorithms, routers with different buffer sizes, variable packet loss rates and round-trip times (RTTs), and small and large numbers of TCP flows. Emulation results show that BBRv2 tolerates much higher random packet loss rates than loss-based algorithms but slightly lower than BBRv1. The results also confirm that BBRv2 has better coexistence with loss-based algorithms and lower retransmission rates than BBRv1, and that it produces low queuing delay even with large buffers.more »When a Tail Drop policy is used with large buffers, an unfair bandwidth allocation is observed among BBRv2 and CUBIC flows. Such unfairness can be reduced by using advanced AQM schemes such as FQ-CoDel and CAKE. Regarding fairness among BBRv2 flows, results show that using small buffers produces better fairness, without compromising high throughput and link utilization. This observation applies to BBRv1 flows as well, which suggests that rate-based model-based algorithms work better with small buffers. BBRv2 also enhances the coexistence of flows with different RTTs, mitigating the RTT unfairness problem noted in BBRv1. Lastly, the paper presents the advantages of using TCP pacing with a loss-based algorithm, when the rate is manually configured a priori. Future algorithms could set the pacing rate using explicit feedback generated by modern programmable switches.« less
  4. The alpha version of Bottleneck Bandwidth and Round-trip Time version 2 (BBRv2) has been recently presented, which aims to mitigate the shortcomings of its predecessor, BBR version 1 (BBRv1). Previous studies show that BBRv1 provides a high link utilization and low queuing delay by estimating the available bottleneck bandwidth. However, its aggressiveness induces unfairness when flows i) use different congestion control algorithms, such as CUBIC, and ii) have distinct round-trip times (RTTs). This paper presents an experimental evaluation of BBRv2, using Mininet. Results show that the coexistence between BBRv2-CUBIC is enhanced with respect to that of BBRv1-CUBIC, as measured by the fairness index. They also show that BBRv2 mitigates the RTT unfairness problem observed in BBRv1. Additionally, BBRv2 achieves a better fair share of the bandwidth than its predecessor when network conditions such as bandwidth and latency dynamically change. Results also indicate that the average flow completion time of concurrent flows is reduced when BBRv2 is used.
  5. This paper describes the deployment of a private cloud and the development of virtual laboratories and companion material to teach and train engineering students and Information Technology (IT) professionals in high-throughput networks and cybersecurity. The material and platform, deployed at the University of South Carolina, are also used by other institutions to support regular academic courses, self-pace training of professional IT staff, and workshops across the country. The private cloud is used to deploy scenarios consisting of high-speed networks (up to 50 Gbps), multi-domain environments emulating internetworks, and infrastructures under cyber-attacks using live traffic. For regular academic courses, the virtual laboratories have been adopted by institutions in different states to supplement theoretical material with hands-on activities in IT, electrical engineering, and computer science programs. Topics include Local Area Networks (LANs), congestion-control algorithms, performance tools used to emulate wide area networks (WANs) and their attributes (packet loss, reordering, corruption, latency, jitter, etc.), data transfer applications for high-speed networks, queueing delay and buffer size in routers and switches, active monitoring of multi-domain systems, high-performance cybersecurity tools such as Zeek’s intrusion detection systems, and others. The training platform has been also used by IT professionals from more than 30 states, for self-pace training.more »The material provides training on topics beyond general-purpose network, which are usually overlooked by practitioners and researchers. The virtual laboratories and companion material have also been used in workshops organized across the country. Workshops are co-organized with organizations that operate large backbone networks connecting research centers and national laboratories, and colleges and universities conducting teaching and research activities.« less
  6. Abstract Sputum induction is a non-invasive method to evaluate the airway environment, particularly for asthma. RNA sequencing (RNA-seq) of sputum samples can be challenging to interpret due to the complex and heterogeneous mixtures of human cells and exogenous (microbial) material. In this study, we develop a pipeline that integrates dimensionality reduction and statistical modeling to grapple with the heterogeneity. LDA(Latent Dirichlet allocation)-link connects microbes to genes using reduced-dimensionality LDA topics. We validate our method with single-cell RNA-seq and microscopy and then apply it to the sputum of asthmatic patients to find known and novel relationships between microbes and genes.
  7. Blockchain technology is the cornerstone of digital trust and systems’ decentralization. The necessity of eliminating trust in computing systems has triggered researchers to investigate the applicability of Blockchain to decentralize the conventional security models. Specifically, researchers continuously aim at minimizing trust in the well-known Public Key Infrastructure (PKI) model which currently requires a trusted Certificate Authority (CA) to sign digital certificates. Recently, the Automated Certificate Management Environment (ACME) was standardized as a certificate issuance automation protocol. It minimizes the human interaction by enabling certificates to be automatically requested, verified, and installed on servers. ACME only solved the automation issue, but the trust concerns remain as a trusted CA is required. In this paper we propose decentralizing the ACME protocol by using the Blockchain technology to enhance the current trust issues of the existing PKI model and to eliminate the need for a trusted CA. The system was implemented and tested on Ethereum Blockchain, and the results showed that the system is feasible in terms of cost, speed, and applicability on a wide range of devices including Internet of Things (IoT) devices.