Partial Reachability in the Internet Core: Definition, Measurement, and Application (Invited Talk)
John Heidemann
USC/Information Sciences Institute
Citation
John Heidemann. Partial Reachability in the Internet Core: Definition, Measurement, and Application (Invited Talk). Technical Report arxiv:tbd. [PDF] [alt PDF]
Abstract
Routing strives to connect the Internet, but failures can result in \textbfpartial reachability in the Internet. This talk identifies partial reachability as an underappreciated area. We will show that partial reachability affects as many users as Internet outages, sometimes persisting for days or years. \newline\quad We suggest three steps are critical to better understand partial reachability: We first present a \textbfconceptual definition of the Internet core, since, surprisingly, today there is no clear definition of what the Internet is. This definition is technical and neutral, based on connectivity, not authority. It enables us to understand peninsulas as persistent partial reachability, and islands, where networks are disconnected from the core. \newline\quad Second, these definitions allow us to realize \textbfalgorithms that detect peninsulas and islands reusing data from existing measurement systems that provide Internet-wide observations over years from thousands of observers. \newline\quad Finally, we show \textbfimportant practical applications of this work. Our new analysis shows that partial reachability affects even more users than outages. We show how to improve RIPE Atlas sensitivity by removing measurement error and persistent reachability problems that otherwise that otherwise overwhelm individual events. Finally, we use our neutral definition to inform Internet policy, including questions about Internet sovereignty.Bibtex Citation
@techreport{Heidemann25a,
author = {Heidemann, John},
title = {Partial Reachability in the Internet Core: Definition, Measurement, and Application (Invited Talk)},
note = {Invited talk at ACM Asian Internet Engineering Conference (AINTEC) 2025 in Manila, Philippines},
number = {arxiv:tbd},
month = nov,
year = {2025},
sortdate = {2025-11-24},
project = {ant, pimawat, bripod, aquarius},
jsubject = {topology_modeling},
jlocation = {johnh: pafile},
keywords = {outage, partial reachability, titao, chiloe, internet fragmenetation},
url = {https://ant.isi.edu/%7ejohnh/PAPERS/Heidemann25a.html},
pdfurl = {https://ant.isi.edu/%7ejohnh/PAPERS/Heidemann25a.pdf},
myorganization = {USC/Information Sciences Institute},
copyrightholder = {authors}
}