Internet Protocol (IP) Addresses
This Appendix establishes the policy for the management and use of Internet Protocol (IP) addresses within the United States Department of Agriculture (USDA).
This directive augments the USDA IP Addressing Plan and other internal and external regulations that establish general policies governing all telecommunications networks, systems, hosts, and routers using Internet Protocol addressing. IP addresses are a Departmental resource that must be managed to ensure that the Office of the Chief Information Officer (OCIO) achieves greater assignment and routing efficiencies.
These addresses assigned to USDA are divided into three categories; the three Class B network addresses used on the USDA Internet Access Network, an 8K (8192) Classless Interdomain Routing (CIDR) block, and the other Class B and Class C network addresses in use in the Department. In each of these categories, addresses were delegated to USDA from the InterNIC and represent official licenses to operate on the Internet. Because of this and the scarcity of the resource in general, care must be taken in the allocation, use and management of these addresses. Routing constraints and capabilities will be an important consideration to be managed during the implementation of an Enterprise Network (EN).
Although the next generation of IP (Ipv6 or Ipng) will provide for a much larger addressing space, its delay in implementation makes it imperative to continue to efficiently manage USDA's current IP address allocation. The importance of assigning these addresses efficiently is necessary to provide the types of Internet-based services which are continuing to be more important to USDA's constituents. The goal of achieving at least 25-50 percent assignment efficiency at the host level must be obtained. With the implementation of an EN the importance of assigning IP addresses efficiently within a geographically based topology is critical. Agencies must work with the OCIO to ensure that variable length addresses are used on Local Area Networks (LAN) to ensure that only the number of needed addresses is assigned to each LAN. The use of classless routing protocols such as Open Shortest Path First can support splitting of Class C network addresses between sites. Address distribution must be based on location of a network supporting limited agency autonomy without compromising the concept of a shared network.