3. Assignment Framework

An assignment is the delegation of authority over a block of IP addresses to an end enterprise. The end enterprise will use addresses from an assignment internally only; it will not sub- delegate those addresses. This section discusses some of the issues involved in assignments and the framework behind the assignment of addresses.

In order for the Internet to scale using existing technologies, use of regional registry services should be limited to the assignment of IP addresses for organizations meeting one or more of the following conditions:

      a)  the organization has no intention of connecting to
          the Internet-either now or in the future-but it still
          requires a globally unique IP address.  The organization
          should consider using reserved addresses from RFC1918.
          If it is determined this is not possible, they can be
          issued unique (if not Internet routable) IP addresses.

      b)  the organization is multi-homed with no favored connection.

      c)  the organization's actual requirement for IP space is
          very large, for example, the network prefix required to
          cover the request is of length /18 or shorter.

All other requestors should contact its ISP for address space or utilize the addresses reserved for non-connected networks described in RFC1918 until an Internet connection is established. Note that addresses issued directly from the IRs,(non-provider based), are the least likely to be routable across the Internet.

3.1. Common Registry Requirements

Because the number of available IP addresses on the Internet is limited, the utilization rate of address space will be a key factor in network number assignment. Therefore, in the best interest of the Internet as a whole, specific guidelines have been created to govern the assignment of addresses based on utilization rates.

Although topological issues may make exceptions necessary, the basic criteria that should be met to receive network numbers are listed below:

                25% immediate utilization rate
                50% utilization  rate within 1 year

The utilization rate above is to be used as a guideline, there may be be occasions when the 1 year rate does not fall exactly in this range. Organizations must exhibit a high confidence level in its 1 year utilization rate and supply documentation to justify the level of confidence.

Organizations will be assigned address space based on immediate utilization plus 1 year projected utilization. A prefix longer than /24 may be issued if deemed appropriate. Organizations with less than 128 hosts will not be issued an IP address directly from the IRs. Organizations may be issued a prefix longer than /24 if the organization can provide documentation from a registry recognized ISP indicating the ISP will accept the long prefix for injection into the global routing system.

Exceptions to the criteria will not be made based on insufficient equipment without additional detailed justification. Organizations should implement variable length subnet mask (VLSM) internally to maximize the effective utilization of address space. Address assignments will be made under the assumption that VLSM is or will be implemented.

IP addresses are valid as long as the criteria continues to be met. The IANA reserves the right to invalidate any IP assignments once it is determined the the requirement for the address space no longer exists. In the event of address invalidation, reasonable efforts will be made by the appropriate registry to inform the organization that the addresses have been returned to the free pool of IPv4 address space.

3.2. Network Engineering Plans

Before a registry makes an assignment, it must examine each address space request in terms of the requesting organization's networking plans. These plans should be documented, and the following information should be included:

      1.  subnetting plans, including subnet masks and number of
          hosts on each subnet for at least one year

      2.  a description of the network topology

      3.  a description of the network routing plans, including the
          routing protocols to be used as well as any limitations.

The subnetting plans should include:

      a)  a tabular listing of all subnets on the network

      b)  its associated subnet masks

      c)  the estimated number of hosts

      d)  a brief descriptive remark regarding the subnet.

If subnetting is not being used, an explanation why it cannot be implemented is required. Care must be taken to ensure that the host and subnet estimates correspond to realistic requirements and are not based on administrative convenience.

3.3. Previous Assignment History

To promote increased usage of address space, the registries will require an accounting of address space previously assigned to the enterprise, if any. In the context of address space allocation, an "enterprise" consists of all divisions and/or subsidiaries falling under a common parent organization. The previous assignment history should include all network numbers assigned to the organization, plus the network masks for those networks and the number of hosts on each (sub-)network. Sufficient corroborating evidence should be provided to allow the assigning registry to be confident that the network descriptions provided are accurate. Routing table efficiency will be taken into account by the regional registries and each request will be handled on a case by case basis.

3.4. Network Deployment Plans

In order to assign an appropriate amount of space in the required time frame, a registry may request deployment plans for a network. Deployment plans should include the number of hosts to be deployed per time period, expected network growth during that time period, and changes in the network topology that describe the growth.

3.5. Organization Information

A registry may request that an organization furnish a published description verifying that the organization is what it claims to be. This information can consist of brochures, documents of incorporation, or similar published material.

3.6. Expected Utilization Rate

As stated in the foregoing text, one of the key factors in determining how much address space is appropriate for an organization is the expected utilization rate of the network. The expected utilization rate is the number of hosts connected to the network divided by the total number of hosts possible on the network. In addition, the estimated number of hosts should be projected over a reasonable time frame, i.e., one in which the requesting enterprise has a high level of confidence. The minimal utilization rate is set by the IANA and may be changed at any time. New utilization rates may be enforced by the regional registries prior to updating the written policy.