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
On 03/07/2025 08:49:07, "Lu Heng via NANOG" <nanog@lists.nanog.org> wrote
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 is that different from a regular provider assigning space (a LIR in RIPE terms)? They just need to keep the RIR data current for all their assignments, they are in no sense a mini RIR, that is a different function. As they are just renting out space that otherwise would have been allocated to a LIR then they should operate as a LIR. brandon
Hi Brandon: The difference is control. If you lease to a different network, or give an IP to a server you rented to a customer, yes, in both cases you will have customer consensus to renumber them, but since leasing at minimum /24, but most hosting customer are in single IP, the difficulty and challenge are quite different. The discussion I like to see if there will be an best operation practice in assigning those IPs to avoid fragmentation in the long run. On Thu, 3 Jul 2025 at 18:00, Brandon Butterworth via NANOG < nanog@lists.nanog.org> wrote:
On 03/07/2025 08:49:07, "Lu Heng via NANOG" <nanog@lists.nanog.org> wrote
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 is that different from a regular provider assigning space (a LIR in RIPE terms)? They just need to keep the RIR data current for all their assignments, they are in no sense a mini RIR, that is a different function.
As they are just renting out space that otherwise would have been allocated to a LIR then they should operate as a LIR.
brandon
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-- -- Kind regards. Lu
On 03/07/2025 11:04:50, "Lu Heng" <h.lu@anytimechinese.com> wrote:
The difference is control.
If you lease to a different network, or give an IP to a server you rented to a customer, yes, in both cases you will have customer consensus to renumber them, but since leasing at minimum /24, but most hosting customer are in single IP, the difficulty and challenge are quite different.
I don't see a difference, if I assign a customer a block of any size it is going to be very hard to have them renumber, probably equally hard if they lease it as the problems for them are exactly the same. A leaser probably has it easier as there would be a specific term to the lease which they can let lapse if they won't agree to a change. The lease would contain any terms necessary for in term changes, if it doesn't then the only option is wait until the term end.
The discussion I like to see if there will be an best operation practice in assigning those IPs to avoid fragmentation in the long run.
It used to be that if you had a customer expected to take incremental chunks of space you'd sparsely assign so that you could grow their assignment in the adjacent free space. There is no longer the luxury of abundant space to do that unless you hoarded lots or use IPv6. Without a method to dynamically re assign space to defragment (flashbacks to running norton utilities) I don't see a way to avoid fragmentation. brandon
participants (2)
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Brandon Butterworth -
Lu Heng