PI Assignment Size

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This proposal allows for End Users who request a Provider Independent IPv4 address assignment to be assigned limited additional address space to make the assignment size a multiple of /24. The End User must demonstrate the intent to multihome the assignment.

The scope of this proposal is twofold:

1. to allow some flexibility in terms of PI assignment so that there is less incentive for End Users to exaggerate or falsify information on their application forms, and

2. to provide a mechanism to prevent this policy proposal from being abused by End Users who wish to apply for arbitrarily large amounts of PI address space.

Policy Text

b. New policy text

[The following text is to appear in the RIPE policy document ripe-527, “IPv4 Address Allocation and Assignment Policies for the RIPE NCC Service Region Link: /publications/docs/ripe-527/ ”, if the proposal reaches consensus]

6.10 Provider Independent IPv4 Assignments for Multihoming

The RIPE NCC will assign additional contiguous IPv4 addresses to an End User in order to make the assignment size a multiple of a /24 if an End User demonstrates:

-the need for Provider Independent (PI) IPv4 address space; and

-the intent to announce this address space for the purpose of multihoming to two or more Autonomous Systems which the End User does not own or control.

Cumulatively, no more than 255 additional IPv4 addresses may be assigned to any particular End User for the purposes outlined above.

Rationale

a. Arguments supporting the proposal

It is generally understood that the minimum prefix size which is generally routable on the Internet is a /24. The first paragraph acknowledges this and ensures that if the End User needs address space, they will not be assigned prefixes which are effectively useless from a routing point of view.

Removal of discrimination: prefixes of /25 and longer are routinely filtered by many network service providers

~~This proposal suggests to have the minimum assignment size for PI assignments to be a /24 when routing is a major issue for a multihoming End User.~~

~~a. Arguments Supporting the Proposal~~

~~PI prefixes longer than a /24 are not very likely to be routed~~ on the Internet. As many End Users who apply for PI assignments do so for the purposes of small-scale multi-homing, in practice the current assignment policies discriminate against these End Users.

Good stewardship: there is significant evidence that End User applications significantly exaggerate their IP addressing requirements when applying for PI assignments in order to make their application qualify for a small PI assignments. By removing the incentive for End Users to exaggerate on PI assignment application forms where that address space is required for multihoming, ~~Current policy requires justification of the amount of address space and the assignment size depends on the number of IP addresses needed by the End User. For example,~~ the RIPE NCC can perform better stewardship of IP number resources.

Precedent exists: /24-aligned PI assignment requests are accepted by other RIRs. This demonstrates that acceptance of this policy will not create any new or undesirable precedents for global IP address assignment policies.

Negligible effect: There is no evidence to suggest that implementation of this policy will have an appreciable effect on the IPv4 depletion rate, as the current policy requirements are routinely ignored due to exaggerated utilisation claims.

Discussion

The last suggested paragraph of 6.10 qualifies the first paragraph in the following ways:

1. It allows multihomed End Users with a requirement for one or more IPv4 PI addresses to qualify for a /24.

2. It allows multihomed End Users who can demonstrate a need for marginally more than a /24 to apply for two /24s, or in general to assign one more /24 to an End User who can justify at least a single /24 on the basis of the current policies.

3. It stops abuse by ensuring that an End User cannot repeatedly go back to the RIPE NCC to ask for more /24s on the same basis.

The wording used to describe a multihomed End User is inspired by the equivalent policy wording in ARIN, and was chosen to ensure that the global policy divergence is minimised if this policy is passed.

The current IPv4 PI assignment policies implemented by the RIPE NCC are based on the principal of justification by quantity of addresses. While this approach works reasonably well when the End User has a requirement for larger numbers of IPv4 address, it discriminates against organisations who use small quantities of PI addresses, typically for multihoming this address space on the Internet.

The RIPE NCC has previously published PI assignment figures which provide strong circumstantial evidence that many End Users exaggerate the quantities of addresses required on their PI application forms in order to adhere to the current policy guidelines. This is harmful to the RIPE NCC because it means that the organisation is not receiving accurate information on actual address space usage, but rather information based on what is likely to quality for a successful address application.

b. Arguments opposing the proposal

Timescales: it could be argued that on the basis that RIR IPv4 address depletion is likely to occur within less than a year, this policy is too late for there to be any point in implementing it.

Routing policy vs. addressing policy: it has been argued that this policy makes addressing policy contingent on Internet routing policies, and that the two should remain separate.

assign a separate /24 and a /25 of PI address space to an End user when they require only 384 IP addresses. The combination fits with the need of the End User. However, it is very likely that the /25 will be filtered out on the Internet. So the /25 prefix is of no use to the End User and causes address space to be wasted. If the End User is assigned a /23 (two /24s) as suggested in this proposal, the End User will have fewer problems in terms of filtering. The extra address space assigned will be a /25 and can be used in the future depending on the End User’s growth. This extra /25 is also the same amount of address space that cannot be used (but assigned) in the first case.

The proposal also suggests to add an assignment criteria to make sure the PI space is assigned to those networks that really need it. Multihoming seems to be the major motivation for the End User organisations in their preference to receive PI address space instead of PA.

~~b. Arguments Opposing the Proposal~~

~~One can argue that the proposal has the potential for unnecessary address space to be assigned (although not more than a /24 per assignment).~~

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 directs the RIPE NCC to assign IPv4 PI space in multiples of a /24 when the end-user demonstrates the intent to multi-home the address space to at least two autonomous systems that the end-user does not control.

This may result in more address space being assigned than would otherwise be justified. Therefore the RIPE NCC shall ensure that the total amount of "extra" space held by the end-user will not exceed 255 IPs, even if the end-user receives multiple IPv4 PI assignments over the years.

B. Impact of Policy on Registry and Addressing System

Address/Internet Number Resource Consumption: