---------------------------------------------------------------------- prop-111-v004 Request-based expansion of IPv6 default allocation size ---------------------------------------------------------------------- Author: Tomohiro Fujisaki fujisaki@syce.net 1. Problem statement -------------------- IPv6 minimum allocation size to LIRs is defined as /32 in the "IPv6 address allocation and assignment policy"[1]. It's better to expand this minimum allocation size up to /29 (/32 - /29) since: - Before sparse allocation mechanism implemented in late 2006, /29 was reserved for all /32 allocations by sequential allocation method made from those old /23 blocks. These reserved blocks might be kept unused in the future. - Sparse allocation mechanism was implemented in late 2006 with a /12 allocation from the IANA. Under the sparse allocation mechanism, there is no reservation size defined, and the space between allocations continues to change, depending on the remaining free pool available in APNIC. However, the "APNIC guidelines for IPv6 allocation and assignment requests"[2] stated: "In accordance with APNIC's "IPv6 address allocation and assignment policy", where possible, subsequent delegations to the same resource holder are made from an adjacent address block by growing the delegation into the free space remaining, unless disaggregated ranges are requested for multiple discrete networks." So, it is expected that allocation up to /29 is guaranteed for consistency with allocations above. Based on the current situation, contiguous allocation of /29 can still be accommodated even under the sparse allocation mechanism (Current /32 allocations from the /12 block can grow up to /24 at this stage). - After amended HD Ratio (0.94) and base calculation size (/56) was introduced (prop-031 and prop-033), to obtain address blocks larger than /32 and to request additional address blocks became harder especially for small and middle size ISPs. - For traffic control purpose, some LIRs announce address blocks longer than /32 (e.g. /35). However, some ISPs may set filters to block address size longer than /32 since some filtering guidelines recommend to filter longer prefix than /32([3][4]). If LIRs have multiple /32, they can announce these blocks and its reachability will be better than longer prefix. - If an LIR needs address blocks larger than /32, LIRs may tend to announce as a single prefix if a /29 is allocated initially at once. i.e., total number of announced prefixes in case 1 may be smaller than in case 2. case 1: The LIR obtains /29 at the beginning of IPv6 network construction. case 2: The LIR obtains /32, and /31, /30 additionally with the subsequent allocation mechanism. 2. Objective of policy change ----------------------------- This proposal modifies the eligibility for an organization to receive or extend an IPv6 address space up to a /29 (/32 -/29) by explaining how the extended space up to /29 will be used. 3. Situation in other regions ----------------------------- RIPE-NCC: The policy "Extension of IPv6 /32 to /29 on a per-allocation vs per-LIR basis" is adopted in RIPE-NCC and LIRs in RIPE region can get up to /29 by default. 4. Proposed policy solution ---------------------------- - Change the text to "5.2.2 Minimum initial allocation size" of current policy document as below: Organizations that meet the initial allocation criteria are eligible to receive an initial allocation of /32. The organizations can receive up to /29 by providing utilization information of the whole address space. - Change /32 to /29 in "5.2.3 Larger initial allocations” Initial allocations larger than /29 may be justified if: - Add following text as 5.3.4 5.3.4 Extend existing allocations to /29 LIRs that hold one or more IPv6 allocations are able to request extension of each of these allocations up to a /29 without meeting the utilization rate for subsequent allocation by providing their network plan to show how the whole address space will be used. 5. Explain the advantages of the proposal ----------------------------------------- - It is possible to utilize address blocks which is potentially unused into the future. - Organizations can design their IPv6 networks more flexibly. - It will be possible for LIRs to control traffic easier. 6. Explain the disadvantages of the proposal -------------------------------------------- Some people may argue this will lead to inefficient utilization of IPv6 space since LIRs can obtain huge address size unnecessarily. However, this will not happen because larger address size needs higher cost to maintain that address block. 7. Impact on resource holders ----------------------------- NIRs must implement this policy if it is implemented by APNIC. 8. References (if required) --------------------------- [1] IPv6 address allocation and assignment policy http://www.apnic.net/policy/ipv6-address-policy [2] APNIC guidelines for IPv6 allocation and assignment requests https://www.apnic.net/publications/media-library/documents/resource-guidelines/ipv6-guidelines [3] Packet Filter and Route Filter Recommendation for IPv6 at xSP routers https://www.team-cymru.org/ReadingRoom/Templates/IPv6Routers/xsp-recommendations.html [4] IPv6 BGP filter recommendations http://www.space.net/~gert/RIPE/ipv6-filters.html