As the author of the original policy in question, I agree this fix is a valid correction to the formula and suggest that it be implemented through the editorial process.
This proposal does not change the intent or meaning of the policy, it merely corrects a minor math error in the text. Owen > On Jul 12, 2025, at 04:09, William Herrin <[email protected]> wrote: > > Hi folks, > > Just a reminder - the ARIN public policy process runs on positive > consensus not silent assent. If you're okay with this policy draft as > written, we need to hear you say it. If you agree there's a problem > but want to see a different solution, we need to hear you say that > too. If the advisory council hears nothing, we will eventually abandon > the draft and the problematic section of the NRPM will persist until > someone figures out how to abuse it. > > Regards, > Bill Herrin > > >> On Wed, Jul 2, 2025 at 2:53 PM William Herrin <[email protected]> wrote: >>> On Tue, Jul 1, 2025 at 11:34 AM ARIN <[email protected]> wrote: >>> Draft Policy ARIN-2025-6: Fix formula in 6.5.2.1c >>> >>> Problem Statement: >>> >>> Sections 6.5.2.1 explains the initial IPv6 ISP/LIR allocation in a way that >>> is difficult to follow and the formula in section (c) does not match the >>> remainder of the text. >>> >>> Policy Statement: >>> >>> In 6.5.2.1c, replace: >>> >>> "This calculation can be summarized as /N where N = P-(X+Y) and P is the >>> organization’s Provider Allocation Unit X is a multiple of 4 greater than >>> 4/3*serving sites and Y is a multiple of 4 greater than 4/3*end sites >>> served by largest serving site." >>> >>> with: >>> >>> "This calculation can be summarized as /N where N = P-(X+Y) and P is the >>> organization’s Provider Allocation Unit, X is a multiple of 4 greater than >>> 4/3*log_2(serving sites) and Y is a multiple of 4 greater than >>> 4/3*log_2(end sites served by largest serving site). >> >> >> FYI, I'm the primary Advisory Council shepherd for this draft policy. >> Here's some explanation: >> >> Section 6.5.2.1c holds the criteria for the _maximum_ initial IPv6 >> allocation for ISPs. They qualify for the number of IPv6 addresses >> described here and may request that much or a smaller block. The >> section is frankly hard to read. Here's what that part of the NRPM >> currently says: >> >> "c. The maximum allowable allocation shall be the smallest >> nibble-boundary aligned block that can provide an equally sized >> nibble-boundary aligned block to each of the requesters serving sites >> large enough to satisfy the needs of the requesters largest single >> serving site using no more than 75% of the available addresses. >> This calculation can be summarized as /N where N = P-(X+Y) and P is >> the organization’s Provider Allocation Unit X is a multiple of 4 >> greater than 4/3*serving sites and Y is a multiple of 4 greater than >> 4/3*end sites served by largest serving site. >> >> d. For purposes of the calculation in (c), an end site which can >> justify more than a /48 under the end-user assignment criteria in >> 6.5.8 shall count as the appropriate number of /48s that would be >> assigned under that policy. >> >> e. For purposes of the calculation in (c), an LIR which has >> subordinate LIRs shall make such reallocations according to the same >> policies and criteria as ARIN. In such a case, the prefixes necessary >> for such a reallocation should be treated as fully utilized in >> determining the block sizing for the parent LIR. LIRs which do not >> receive resources directly from ARIN will not be able to make such >> reallocations to subordinate LIRs and subordinate LIRs which need more >> than a /32 shall apply directly to ARIN." >> >> >> Here's how ARIN staff explained the current implementation of NRPM 6.5.2.1c: >> >> "ARIN staff implements 6.5.2.1.c based on the text. The summarized >> formula is overly complex and inaccurate for your typical IPv6 >> requestor. The text alone is more easily understood by customers and >> implemented by ARIN staff. >> >> ARIN staff calculates Initial allocation sizes by verifying how many >> serving sites the ISP has in the ARIN region, and how many customers >> are served at the largest serving site. ARIN assumes each customer >> will receive a /48 for simplicity and to promote IPv6 transition. >> >> Once the sites and customers are provided by the requestor, ARIN staff >> confirms what size is justified at the largest serving site based on >> the 75% rule. That size is applied to all sites, then checked against >> the 75% rule for the overall allocation justified by the ISP. The ISP >> can opt to request a smaller size. They are not required to request >> the largest justified size, though it is recommended to avoid future >> renumbering. >> >> For example: >> An ISP has 7 sites and 30,000 customers at the largest site. >> >> ARIN assumes each of the 30,000 customers receives a /48. There are >> only 4,096 /48s in a /36, so a /36 is too small. The next >> nibble-boundary aligned subnet is a /32 which has 65,536 /48s. 30,000 >> is less than 75% of 65,536, so the ISP’s largest serving site >> justifies a /32. >> >> Thus, each of the 7 sites receives a /32. The next nibble-boundary >> after /32 is a /28. There are 16 /32s in a /28. 7 /32s of the total 16 >> /32s is less than 75%, so the organization justifies a total >> allocation of a /28. 7 /32s for immediate allocation to each of their >> 7 sites and 9 additional /32s for future growth. >> >> Example 2: >> >> Building off the previous example, if the largest serving site had >> 60,000 customers, then a /32 would be too small. 60,000 is greater >> than 75% of the available 65,536 /48s in a /32. The next >> nibble-boundary aligned subnet is a /28, so the largest serving site >> justifies a /28. Thus, each of the 7 sites receives a /28, so the >> organization justifies a /24." > > > > > -- > William Herrin > [email protected] > https://bill.herrin.us/ > _______________________________________________ > ARIN-PPML > You are receiving this message because you are subscribed to > the ARIN Public Policy Mailing List ([email protected]). > Unsubscribe or manage your mailing list subscription at: > https://lists.arin.net/mailman/listinfo/arin-ppml > Please contact [email protected] if you experience any issues. _______________________________________________ ARIN-PPML You are receiving this message because you are subscribed to the ARIN Public Policy Mailing List ([email protected]). Unsubscribe or manage your mailing list subscription at: https://lists.arin.net/mailman/listinfo/arin-ppml Please contact [email protected] if you experience any issues.
