PI Assignment Size
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.
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. 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 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).