Anycast Polarization in The Wild

Rizvi, ASM and Huang, Tingshan and Esrefoglu, Rasit and Heidemann, John
USC/Information Sciences Institute


ASM Rizvi, Tingshan Huang, Rasit Esrefoglu and John Heidemann 2024. Anycast Polarization in The Wild. Proceedings of the Passive and Active Measurement Workshop (Virtual Location, Mar. 2024). [PDF] [Dataset]


IP anycast is a commonly used method to associate users with services provided across multiple sites, and if properly used, it can provide efficient access with low latency. However, prior work has shown that polarization can occur in global anycast services, where some users of that service are routed to an anycast site on another continent, adding 100‚ÄČms or more latency compared to a nearby site. This paper describes the causes of polarization in real-world anycast and shows how to observe polarization in third-party anycast services. We use these methods to look for polarization and its causes in 7986 known anycast prefixes. We find that polarization occurs in more than a quarter of anycast prefixes, and identify incomplete connectivity to Tier-1 transit providers and route leakage by regional ISPs as common problems. Finally, working with a commercial CDN, we show how small routing changes can often address polarization, improving latency for 40% of clients, by up to 54%.


  author = {Rizvi, ASM and Huang, Tingshan and Esrefoglu, Rasit and Heidemann, John},
  title = {Anycast Polarization in The Wild},
  booktitle = {Proceedings of the  Passive and Active Measurement Workshop},
  year = {2024},
  sortdate = {2024-03-11},
  project = {ant, pimawat, classnet, diiner, sabres},
  month = mar,
  address = {Virtual Location},
  publisher = {Springer},
  jlocation = {johnh: pafile},
  keywords = {anycast, polarization, bgp},
  url = {},
  pdfurl = {},
  blogurl = {},
  dataseturl = {},
  myorganization = {USC/Information Sciences Institute},
  copyrightholder = {Springer}