1. Introduction

The addressing constraints described in this document are largely the result of the interaction of existing router technology, address assignment, and architectural history. After extensive review and discussion, the authors of this document, the IETF working group that reviewed it and the IESG have concluded that there are no other currently deployable technologies available to overcome these limitations. In the event that routing or router technology develops to the point that adequate routing aggregation can be achieved by other means or that routers can deal with larger routing and more dynamic tables, it may be appropriate to review these constraints.

Internet address space is distributed according to the following three goals:

1. Conservation: Fair distribution of globally unique Internet address space according to the operational needs of the end-users and Internet Service Providers operating networks using this address space. Prevention of stockpiling in order to maximize the lifetime of the Internet address space.
2. Routability: Distribution of globally unique Internet addresses in a hierarchical manner, permitting the routing scalability of the addresses. This scalability is necessary to ensure proper operation of Internet routing, although it must be stressed that routability is in no way guaranteed with the allocation or assignment of IPv4 addresses.
3. Registration: Provision of a public registry documenting address space allocation and assignment. This is necessary to ensure uniqueness and to provide information for Internet trouble shooting at all levels.

It is in the interest of the Internet community as a whole that the above goals be pursued. However it should be noted that "Conservation" and "Routability" are often conflicting goals. All the above goals may sometimes be in conflict with the interests of individual end-users or Internet service providers. Careful analysis and judgement is necessary in each individual case to find an appropriate compromise.

The Internet Registry system

In order to achieve the above goals the Internet Registry (IR) hierarchy was established.

The Internet Registry hierarchy consists of the following levels of hierarchy as seen from the top down: IANA, Regional IRs, Local IRs.

IANA

The Internet Assigned Numbers Authority has authority over all number spaces used in the Internet. This includes Internet Address Space. IANA allocates parts of the Internet address space to regional IRs according to its established needs.

Regional IRs

Regional IRs operate in large geopolitical regions such as continents. Currently there are three regional IRs established; InterNIC serving North America, RIPE NCC serving Europe, and AP- NIC serving the Asian Pacific region. Since this does not cover all areas, regional IRs also serve areas around its core service areas. It is expected that the number of regional IRs will remain relatively small. Service areas will be of continental dimensions.

Regional IRs are established under the authority of the IANA. This requires consensus within the Internet community of the region. A consensus of Internet Service Providers in that region may be necessary to fulfill that role.

The specific duties of the regional IRs include coordination and representation of all local IRs in its respective regions.

Local IRs

Local IRs are established under the authority of the regional IR and IANA. These local registries have the same role and responsibility as the regional registries within its designated geographical areas. These areas are usually of national dimensions.