LACeS: an Open, Fast, Responsible and Efficient Longitudinal Anycast Census System
This repository contains the dataset of the Anycast Census (detected /24 Anycast Prefixes), discovered using LACeS. The repository is updated daily.
Contact remi.hendriks@utwente.nl
TLDR:
(AB > 3) || (GCD > 1) when high confidence is needed.(AB > 1) || (GCD > 1) (all) when completeness is needed.The anycast-based approach (AB) suffers from FPs (see MAnycast2). These FPs are especially prevalent when AB has a value of less than 3 (i.e., receiving replies at less than 3 sites).
The latency-based approach (GCD) is highly accurate. However, it has rare cases of FNs when anycast is deployed in small geographic regions (i.e., regional anycast).
If high confidence is needed, ensure that AB is higher than 3 or GCD detects anycast. If completeness is needed, use all prefixes in this census (either methodology detects anycast).
To minimize the impact of our daily probing methodology we scan at a /24 granularity. However, there are cases of partial anycast where the /24 contains both unicast and anycast addresses. Scanning at /32 granularity reveals ~1.0k /24s are partially anycast. We flag these cases using bi-annual measurement data, but partial prefixes are dynamic over time. Future work is providing an API for live measurements.
We use AAAA record addresses from OpenINTEL and TUM’s public IPv6 hitlist IPv6Hitlist. To maintain reasonable probing times, we scan only the first /48 of aliased prefixes. A join with the aliased prefixes set from TUM’s hitlist, should give a more complete list of anycast prefixes.
When making use of this dataset for academic research, please cite the following research paper.
@misc{hendriks2025laces,
title={LACeS: an Open, Fast, Responsible and Efficient Longitudinal Anycast Census System},
author={Remi Hendriks and Matthew Luckie and Mattijs Jonker and Raffaele Sommese and Roland van Rijswijk-Deij},
year={2025},
eprint={2503.20554},
archivePrefix={arXiv},
primaryClass={cs.NI},
url={https://arxiv.org/abs/2503.20554},
}
Following we describe the structure of the provided census files.
* Historical files (going back to March 21, 2024)
YYYY/MM/DD/IPv4.parquet YYYY/MM/DD/IPv6.parquet YYYY/MM/DD/IPv4.csv YYYY/MM/DD/IPv6.csv YYYY/MM/DD/stats
#### Structure:
**Example**
IPv4.parquet
```bash
prefix AB_ICMPv4 AB_TCPv4 AB_DNSv4 GCD_ICMPv4 GCD_TCPv4 partial backing_prefix ASN locations
1.1.1.0/24 29 29 29 67 30 False 1.1.1.0/24 13335 [{'city': 'Honolulu', 'code_country': 'US', 'id': 'HNL', 'latitude': 21.3187007904, 'longitude': -157.9219970703}, ... ]
Columns
Prefix: The candidate anycast /24 prefix being analyzed (e.g., “1.0.0.0/24”).AB_ICMPv4/v6: Number of locations found using the anycast-based method (ICMP).AB_TCPv4/v6: Number of locations found using the anycast-based method (TCP SYNACK).AB_DNSv4/v6: Number of locations found using the anycast-based method (DNS/UDP).GCD_ICMPv4/v6: Number of sites found using the latency-based method (ICMP).GCD_TCPv4/v6: Number of sites found using the latency-based method (TCP).partial: Whether we detected partial anycast in this prefix (IPv4 only).backing_prefix: Corresponding IP routing table prefix (as observed using RouteViews).ASN: ASN(s) announcing the prefix (MOASes are separated by _).locations: Locations found using GCD (ICMP locations preferred).
AB and GCD detect anycast if number of sites found is larger than 1.
backing_prefix and ASN are from CAIDA’s prefix2as dataset.locations has the following format:
city: Geolocated city using iGreedy’s algorithm.country_code: 2 character country code (ISO 3166-1 alpha-2).id: Nearest airport IATA 3 letter code.lat: Latitude of airport.lon: Longitude of airport.Due to NDA agreements with hitlists providers, only /24 prefixes marked at least by one measurement method as anycast are reported.
IPv4.csv
prefix,number_of_sites,backing_prefix
1.1.1.0/24,67,1.1.1.0/24
We provide a .csv (with limited data) as it can be loaded using GitHub’s Web UI for ease-of-access. This contains the /24-IPv4 or /48-IPv6 prefixes detected as anycast using GCD, alongside the number of sites found using GCD, and the backing prefix.
We make all tooling publicly available (licensed under MPL2.0).