Dear NANOG community, With the increasing prevalence of address‐space leasing—effectively operating as “mini‐RIRs” for IP distribution—fragmentation of address blocks has become a critical concern. How are network operators and registry practitioners today tackling the challenge of fragmentation in IP address allocation? - Are there any comprehensive research studies or white papers that survey fragmentation mitigation techniques or propose novel allocation algorithms? - What best operational practices have emerged for assigning large, contiguous prefixes (e.g. /16) rather than multiple smaller blocks (e.g. /18s) across diverse networks? - How do operators handle geo‐locational constraints and customer reluctance to renumber when reassigning addresses across multiple regions or networks? Any insights, references, or case studies you can share would be greatly appreciated. -- -- Kind regards. Lu