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Summary of Proposal:

This proposal describes how the RIPE NCC should distribute IPv4 address space from the final /8 address block it receives from the IANA. The proposal only discusses PA allocations; any other type of allocation or assignment is out of scope for this proposal.

Policy Text:

New Policy Text:

5.6 Use of last /8 for PA Allocations

The following policies come into effect as soon as RIPE NCC is required to make allocations from the final /8 it receives from the IANA. From then on the distribution of IPv4 address space will only be done as follows:

  1. Allocations for LIRs from the last /8

    On application for IPv4 resources LIRs will receive IPv4 addresses according to the following:

    1. LIRs may only receive one allocation from this /8. The size of the allocation made under this policy will be exactly one /22.
    2. LIRs receive only one /22, even if their needs justify a larger allocation.
    3. LIRs may apply for and receive this allocation once they meet the criteria to receive IPv4 address space according to the allocation policy in effect in the RIPE NCC service region at the time of application.
    4. Allocations will only be made to LIRs if they have already received an IPv6 allocation from an upstream LIR or the RIPE NCC.

  2. Unforeseen circumstances

    1. A /16 will be held in reserve for some future uses, as yet unforeseen. The Internet is a disruptive technology and we cannot predict what might happen. Therefore it is prudent to keep a /16 in reserve, just in case some future requirement makes a demand of it. In the event that this /16 remains unused at the time the remaining /8 covered by this policy has been distributed, it returns to the pool to be distributed as per clause 1.

address space from its last /8 worth of IPv4 address space.


a. Arguments supporting the proposal

The final /8 of IPv4 address space received from the IANA worth of address space will have a special policy applicable to it in the RIPE region. This avoids the risk of one or a few organisations consuming the entire block with a well crafted and fully justified resource application. The proposal attempts to ensure that no organisation lacks real routable IPv4 address space during the coming transition to IPv6. It is very important that new entrants also have the chance to get some IPv4 space before it totally runs out because a small block of IPv4 addresses will be necessary for a while before the Internet can run on an IPv6-only platform.

b. Arguments Opposing the Proposal

IPv4 PI addresses will not be assigned through this policy.

Some organisations may believe and can demonstrate that their IPv4 requirements are larger than the minimum allocation or assignment sizes in the RIPE region. But this final /8 is not intended as a solution to the growth needs of a few organisations, but for assisting with the transition from IPv4 to IPv6.

Some organisations may set up multiple LIR registrations in an effort to get more address space than proposed. The RIPE NCC must be vigilant regarding these, but the authors accept that it is hard to ensure complete compliance.

Note: In order to provide additional information related to the proposal, details of an impact analysis carried out by the RIPE NCC are documented below. The projections presented in this analysis are based on existing data and should be viewed only as an indication of the possible impact that the policy might have if the proposal is accepted and implemented.

A. RIPE NCC's Understanding of the Proposed Policy

This proposal describes the distribution of IPv4 address space from the moment that the RIPE NCC would have to begin using the final /8 received from the IANA. It only provides for making /22 (PA) Allocations to LIRs and not for making any other kind of allocation or assignment. The final resource request which provides the "trigger" will not be filled from this final /8.

An LIR is eligible to receive one single /22 allocation provided they qualify for an additional allocation under the "normal" policy and have an IPv6 allocation from the RIPE NCC or upstream LIR.

A /16 of this final /8 will be reserved for "unforeseen circumstances". The "unforeseen circumstances" for which this /16 could be used are not defined in The proposed policy will be triggered once the RIPE NCC holds the equivalent of a /8 of unallocated and/or unassigned IPv4 Address Space. This applies solely to the address space that has been allocated to the RIPE NCC by the IANA. Address space blocks with legacy assignments or allocations are outside the scope of this proposal. This

/16 will be used to make /22 allocations, if the rest of the /8 is used before a new policy is made for the /16.The address space that is address space may not be a single aggregated /8 and can contain prefixes as long as a /29 or more. Therefore it is possible that at some point the RIPE NCC will be unable to allocate a single /22 block to an LIR and will have to allocate multiple prefixes that total 1,024 IP addresses. Because of this situation, there will effectively no longer be a minimum allocation size within the RIPE NCC service region when this happens.

It is possible that the final request for an allocation that causes this policy to be triggered may only be partially fulfilled by the RIPE NCC before the threshold of the last /8 is reached.

Under the current policies, when this proposed policy is triggered, the RIPE NCC will no longer assign ASSIGNED PI and ASSIGNED ANYCAST space. If proposal 2010-01, “Temporary Internet Number Assignment Policies”, is accepted we will still assign temporary ASSIGNED PI space from a separate pool that we will reserve for this purpose.

It is possible that some IPv4 Address Space will be

returned to the RIPE NCC after this policy comes into effect, will be re-allocated according to this same policy. even after this proposed policy has been triggered. Any such returned space will be added to the pool that is available for /22 allocations to LIRs under this proposed policy, even if the returned space causes the unallocated pool to rise to more than a /8 in total.

B. Impact of Policy on Registry and Addressing System

Address/Internet Number Resource Consumption:
After analysing the data that is currently available, the RIPE NCC does not anticipate that any significant impact will be caused if this proposal is implemented.

To prevent this policy from being triggered while there is still free space in other /8s, the final few "normal" requests will most likely be assigned and/or allocated as multiple, discontinuous prefixes. The last assignment or allocation will not be filled completely.

If accepted, this proposed policy will slow down the consumption of the last IPv4 addresses because each LIR will receive only one allocation and no PI assignments will be made from the last /8.

Currently, the RIPE NCC has about 7000 members. The equivalent of a /8 will accommodate 16,384 allocations of a size /22. The /16 set aside as a reserve reduces the number by 64, leaving a potential of 16,320 allocations to be made under this proposed policy. Thus the proposal accommodates for explosive growth of the RIPE NCC membership or could enable the RIPE NCC to have IPv4 space for many years to come.


As mentioned above, there is possibility that the last /8 may not be a single aggregated /8 and may contain prefixes as long as a /29. However, for the sake of this analysis we have looked at the case of a block where the longest prefix will be a /22.

Ultimately, once the reserved /16 is used, the proposal splits the last /8 into 16,384 allocations of size /22. This is significantly higher than the fragmentation observed in any of the /8s which have been allocated to the RIPE NCC before. Most of these /8s have less than 1,000 allocations and assignments (source: Link: ).

Compared to the current global routing table statistics as reported in Link: , the number of prefixes would go up by 5% when all 16,384 allocations have been handed out. This growth could come in two stages. In the first stage we could see a rapid increase in a relatively short time when the threshold of the last /8 is reached and existing LIRs matching the criteria each apply for a /22. In the second stage, we could see the extra growth happen more gradually while new entrants join the RIPE NCC and apply for their /22 of IPv4.

C. Impact of Policy on RIPE NCC Operations/Services

Registration Services:
Current policies and procedures allow one organisation to set up and operate multiple LIRs, each with their own allocations. There are many organisations that do this. It is possible that some organisations will open multiple LIRs to obtain more than one /22. There is currently no basis for denying any organisation this right.

The policy proposal requires that the RIPE NCC is vigilant regarding those organisations that set up multiple LIRs in order to circumvent the "one IPv4 allocation per LIR" restriction. Although the authors accept that it is hard to ensure complete compliance, a level of compliance is required. At the moment the RIPE NCC has no mechanisms to control the number of LIRs per organisation. To comply with the proposed policy, such control mechanisms must be developed.

D. Legal Impact of Policy

This policy proposal has many similarities with the withdrawn policy proposals 2008-06 (Use of final /8 Link: /membership/policies/proposals/2008-06/ ) and 2009-04 (IPv4 Allocation and Assignment to Facilitate IPv6 Deployment Link: /membership/policies/proposals/2009-04/ ) and 2009-04

The RIPE NCC has studied the legal implications of these previous proposals. The conclusions of this study have been published on the Address Policy Working Group mailing list: Link: Link:

and have been presented during the RIPE 59 Meeting:

On the basis of this study, the RIPE NCC does not anticipate that the implementation of this proposed policy would cause any significant legal implications.