KeLLy – Efficient, Scalable Link Layer Topology Discovery

Network infrastructures are becoming increasingly flexible and dynamic not only due to softwarization and virtualization, but also due to increasing mobility in 5G and 6G networks, which consider drones and satellites to be part of the core infrastructure. Since the network topology may change frequently, it becomes challenging to get an up-to-date view of its current state. This paper introduces KeLLy, an efficient, scalable link layer topology discovery algorithm focussing on large-scale networks (evaluated up to 100,000 nodes). KeLLy discovers various large topologies in seconds, guarantees discovery of all nodes (and a high percentage of links), while inducing low, predictable overhead by querying only a subset (4%) of nodes

Coupling Smart Contracts: A Comparative Case Study

When software systems become more complex, it can be advantageous to partition their code into multiple, separate components. In this work, we examine how multiple smart contracts can be coupled to work together. When coupling smart contracts, different design approaches are possible with their own advantages and disadvantages. As an example, we couple two smart contract applications on the Ethereum blockchain: Palinodia and DecentID. Palinodia can be used to ensure the integrity of downloaded executable binaries by checking their hashes against the hashes stored in the blockchain. To make sure that not everyone can modify the data stored on the blockchain, an identity management system is required. This task is fulfilled by DecentID, which provides decentralized identities stored as smart contracts on the blockchain. We evaluate approaches of coupling these two applications and discuss their benefits and drawbacks for this use case

Low-frequency ocean ambient noise on the Chukchi Shelf in the changing Arctic

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bonnel, J., Kinda, G. B., & Zitterbart, D. P. Low-frequency ocean ambient noise on the Chukchi Shelf in the changing Arctic. Journal of the Acoustical Society of America, 149(6), (2021): 4061–4072, https://doi.org/10.1121/10.0005135.This article presents the study of a passive acoustic dataset recorded on the Chukchi Shelf from October 2016 to July 2017 during the Canada Basin Acoustic Propagation Experiment (CANAPE). The study focuses on the low-frequency (250–350 Hz) ambient noise (after individual transient signals are removed) and its environmental drivers. A specificity of the experimental area is the Beaufort Duct, a persistent warm layer intrusion of variable extent created by climate change, which favors long-range acoustic propagation. The Chukchi Shelf ambient noise shows traditional polar features: it is quieter and wind force influence is reduced when the sea is ice-covered. However, the study reveals two other striking features. First, if the experimental area is covered with ice, the ambient noise drops by up to 10 dB/Hz when the Beaufort Duct disappears. Further, a large part of the noise variability is driven by distant cryogenic events, hundreds of kilometers away from the acoustic receivers. This was quantified using correlations between the CANAPE acoustic data and distant ice-drift magnitude data (National Snow and Ice Data Center).This research was supported by the Independent Research and Development Program at WHOI and by the Office of Naval Research (ONR) under Grant Nos. N00014-19-1-2627 and N00014-18-1-2811. J.B. warmly acknowledges D. Cazau (ENSTA Bretagne, France) for helpful discussion and code sharing. The acoustic data collection effort was supported by the ONR under Grant No. N00014-15-1-2196 (Principal Investigator: Y.-T. Lin, WHOI). Thanks also go to crew members of the R/V Sikuliaq and USCGC Healy for assisting in mooring operations. The ITP data were collected and made available by WHOI

Demo: Coexistence of Low Delay and Loss-based Congestion Controls in SDN-based Networks

Congestion controls that focus on achieving a low queuing delay, such as the novel TCP LoLa, can significantly improve the quality-of-experience for delay-sensitive applications. The gradual deployment of such congestion controls, however, is challenging because their data flows get suppressed by flows that use a legacy loss-based congestion control (e.g. CUBIC TCP). This demo shows the advantages of TCP LoLa for interactive applications at the example of a network-enabled version of the well-known PONG game. In addition to that, the demo shows how SDN technology can be used to facilitate the coexistence between low delay and loss-based congestion controls

Towards a Resilient In-Band SDN Control Channel

Towards a Resilient In-Band SDN Control Channe

Kumano Mandara: Portraits, Power, and Lineage in Medieval Japan

This dissertation focuses on two miya mandara depicting the sacred geography of the Kumano region of Japan (late-thirteenth/early-fourteenth centuries). It demonstrates that the paintings were produced at Onjōji, a Tendai Buddhist temple in the eastern foothills of Mount Hiei, and owned by Shōgoin, its sub-temple in Kyoto. These temples were affiliated with the Jimon branch of Tendai associated with the esoteric cleric Enchin (814-891)), and were, by the time of the production of the mandara, in heated doctrinal, institutional, and political dispute over independence from the Tendai headquarters at Enryakuji.Three primary issues related to the mandara are addressed. First is the purpose of their production. The dissertation questions earlier claims that miya mandara primarily functioned as visual tools allowing mental visits to depicted sacred sites in place of expensive and arduous pilgrimages. Rather, it argues that the Kumano mandara were part of a larger contemporaneous discourse that included other forms of written and visual materials—such as the Ippen hijiri-e and Tengu zōshi handscrolls, Shugen shinanshō, and petitions to court—and represented an orchestrated attempt to promote the spiritual superiority and legitimate the institutional autonomy of Onjōji over Enryakuji.Viewed within this context, two atypical features of miya mandara found in the Kumano mandara can be understood: the inclusion of a portrait of Enchin and of the esoteric Diamond and Womb World mandala. Lineage and power being inseparable in the religious and political culture of medieval Japan, the dissertation argues that the purpose of their placement in the Kumano mandara was to claim that the superiority of Onjōji was rooted in both Enchin's Jimon lineage and his form of esoteric Tendai centered at the temple, and that each, in turn, valorized and legitimized Onjōji's claim for superiority over all other temples, especially Enryakuji. Finally, the dissertation takes up the problem of another portrait found in the mandara, which has been identified (without substantiation) as the Shingon esoteric priest Kūkai (774-835). The dissertation contests this attribution, which is inconsistent with its other findings, and offers possible avenues of pursuit for identifying this damaged and controversial portrait