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1. A Hop Away from Everywhere: A View of the Intercontinental Long-haul Infrastructure

   https://doi.org/10.1145/3673660.3655041  

   Carisimo, Esteban; Wang, Caleb J; Weaver, Mia; Bustamante, Fabián; Barford, Paul (June 2024, ACM SIGMETRICS Performance Evaluation Review)

   We present a longitudinal study of intercontinental long-haul links (LHL) - links with latencies significantly higher than that of all other links in a traceroute path. Our study is motivated by the recognition of these LHLs as a network-layer manifestation of transoceanic undersea cables. We present a methodology and associated processing system for identifying long-haul links in traceroute measurements, and report on our findings from. We apply this system to a large corpus of traceroute data and report on multiple aspects of long haul connectivity including country-level prevalence, routers as international gateways, preferred long-haul destinations, and the evolution of these characteristics over a 7 year period. 

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2. A Hop Away from Everywhere: A View of the Intercontinental Long-haul Infrastructure

   Carisimo, Esteban; Wang, Caleb J; Weaver, Maria; Bustamante, Fabian E; Barford, Paul (July 2024, ACM SIGMETRICS Performance Evaluation Review)

   We present a longitudinal study of intercontinental long-haul links (LHL) - links with latencies significantly higher than that of all other links in a traceroute path. Our study is motivated by the recognition of these LHLs as a network-layer manifestation of transoceanic undersea cables. We present a methodology and associated processing system for identifying long-haul links in traceroute measurements, and report on our findings from. We apply this system to a large corpus of traceroute data and report on multiple aspects of long haul connectivity including country-level prevalence, routers as international gateways, preferred long-haul destinations, and the evolution of these characteristics over a 7 year period. 

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3. Application of quantum-limited optical time transfer to space-based optical clock comparisons and coherent networks

   https://doi.org/10.1063/5.0170107  

   Caldwell, Emily_D; Sinclair, Laura_C; Deschenes, Jean-Daniel; Giorgetta, Fabrizio; Newbury, Nathan_R (January 2024, APL Photonics)

   With the demonstration of quantum-limited optical time transfer capable of tolerating the losses associated with long ground-to-space links, two future applications of free-space time transfer have emerged: intercontinental clock comparisons for time dissemination and coherence transfer for future distributed sensing in the mm-wave region. In this paper, we estimated the projected performance of these two applications using quantum-limited optical time transfer and assuming existing low-size, low-weight, and low-power hardware. In both cases, we limit the discussion to the simplest case of a single geosynchronous satellite linked to either one or two ground stations. One important consideration for such future space-based operations is the choice of reference oscillator onboard the satellite. We find that with a modestly performing optical reference oscillator and low-power fiber-based frequency combs, quantum-limited time transfer could support intercontinental clock comparisons through a common-view node in geostationary orbit with a modified Allan deviation at the 10−16 level at 10-s averaging time, limited primarily by residual turbulence piston noise. In the second application of coherence transfer from ground-to-geosynchronous orbit, we find the system should support high short-term coherence with ∼10 millirad phase noise on a 300 GHz carrier at essentially unlimited integration times. 

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4. A Manifold View of Connectivity in the Private Backbone Networks of Hyperscalers

   https://doi.org/10.1145/3604620  

   Salamatian, Loqman; Anderson, Scott; Mathews, Joshua; Barford, Paul; Willinger, Walter; Crovella, Mark (August 2023, Communications of the ACM)

   As hyperscalers such as Google, Microsoft, and Amazon play an increasingly important role in today's Internet, they are also capable of manipulating probe packets that traverse their privately owned and operated backbones. As a result, standard traceroute-based measurement techniques are no longer a reliable means for assessing network connectivity in these global-scale cloud provider infrastructures. In response to these developments, we present a new empirical approach for elucidating connectivity in these private backbone networks. Our approach relies on using only lightweight (i.e., simple, easily interpretable, and readily available) measurements, but requires applying heavyweight mathematical techniques for analyzing these measurements. In particular, we describe a new method that uses network latency measurements and relies on concepts from Riemannian geometry (i.e., Ricci curvature) to assess the characteristics of the connectivity fabric of a given network infrastructure. We complement this method with a visualization tool that generates a novel manifold view of a network's delay space. We demonstrate our approach by utilizing latency measurements from available vantage points and virtual machines running in datacenters of three large cloud providers to study different aspects of connectivity in their private backbones and show how our generated manifold views enable us to expose and visualize critical aspects of this connectivity. 

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5. FlashRoute: Efficient Traceroute on a Massive Scale

   https://doi.org/10.1145/3419394.3423619  

   Huang, Yuchen; Rabinovich, Michael; Al-Dalky, Rami (October 2020, Proceedings of the ACM Internet Measurement Conference)

   null (Ed.)

   We propose a new traceroute tool, FlashRoute for efficient large-scale topology discovery. FlashRoute reduces the time required for tracerouting the entire /24 IPv4 address space by a factor of three and half compared to previous state of the art. Additionally, we present a new technique to measure hop-distance to a destination using a single probe and uncover a bias of the influential ISI Census hitlist [18] in topology discovery. 

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