Starting March 2018 CAIDA makes topology data less than one year old available via Information Marketplace for Policy and Analysis of Cyber-risk and Trust (IMPACT).
Older IPv4 topology data (older than one year old), and all IPv6 data are available as public datasets. You can obtain access using this form.
If your research involves:
CAIDA strongly favors wide dissemination of its datasets to legitimate researchers, and CAIDA also takes seriously its obligation to responsibly disclose datasets which may present a risk if misused.
Also, please, report your publication to CAIDA.