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Network Working Group                                          E. GerichRequest for Comments: 1814                            Merit Network Inc.Category: Informational                                        June 1995Unique Addresses are GoodStatus of this Memo   This memo provides information for the Internet community.  This memo   does not specify an Internet standard of any kind.  Distribution of   this memo is unlimited.Abstract   The IAB suggests that whileRFC 1597 establishes reserved IP address   space for the use of private networks which are isolated and will   remain isolated from the Internet, any enterprise which anticipates   external connectivity to the Internet should apply for a globally   unique address from an Internet registry or service provider.Introduction   With the advent ofRFC 1466 andRFC 1597 the criteria for the   allocation of unique IP numbers and the reservation of unique IP   numbers have been defined. The IAB and the IANA wish to offer   guidance to the Internet registries as to the application of these   two documents.  The author submits this document as an informational   RFC on behalf of the Internet Architecture Board and the IANA.Guidance to Internet RegistriesRFC 1466 lists the criteria to which Internet registries should   conform.  One of the criteria is that the Internet registry is   committed to allocate IP numbers according to the guidelines   established by the IANA and the IR. Those guidelines (for Classes A,   B, and C addresses) are documented inRFC 1466.   Internet Registries have agreed to comply with the guidelines   established byRFC 1466 and therefore, if an organization meets the   size requirement for the requested address(es) and submits an   engineering plan, the organization has fulfilled the necessary   requirements.  The Internet Registry will make the allocation based   on the established criteria.Gerich                       Informational                      [Page 1]

RFC 1814               Unique Addresses are Good               June 1995   The preconditions defined inRFC 1466 are limited to number of hosts   and subnets as well as an engineering plan.  The existence of private   address space (RFC 1597) shall not prevent an enterprise from   obtaining public address space according to the allocation criteria   (currently,RFC 1466).   An enterprise may be required by a Internet registry to submit an   engineering plan documenting a realistic deployment schedule and   reasonable attention to conservation of address space to support the   size of the enterprise's request for globally unique IP addresses.   It is perfectly appropriate for an Internet registry to inform an   organization of the provisions ofRFC 1597.  Any organization   considering the use of private network numbers should carefully   consider the potential advantages and possible problems as discussed   in RFCs 1597 and 1627.RFC 1597 establishes reserved IP address space for the use of private   networks which are isolated and will remain isolated from the   Internet. ThusRFC 1597 documents a way that private enterprises may   assure that their networks will remain segregated from the Internet.   The addresses designated inRFC 1597 should not be routed by the   Internet.   Any enterprise with a significantly large number of hosts which might   require external connectivity to the Internet at the IP layer should   apply for a block of globally unique addresses from an Internet   registry.  Enterprises with a small to medium number of hosts that   require external connectivity to the Internet at the IP layer should   expect to use globally unique addresses for these hosts, assigned to   them by their current Internet service provider from its own assigned   addresses, if it has such addresses to distribute.   If an enterprise with a small to medium number of hosts desires   unique IP addresses, and is unable to obtain them under reasonable   conditions from a service provider, or has no service provider, the   Internet registries are recommended to assign such addresses without   conditions with respect to service provider selection.  The   registries should make clear to the enterprise that when the   enterprise decides to connect to the Internet, the assigned addresses   are no guarantee of Internet-wide IP connectivity. In fact, some   service providers may require renumbering as a condition of   connectivity.   Any organization which anticipates having external connectivity is   encouraged to apply for a globally unique IP address.  Globally   unique addresses are necessary to differentiate between destinations   on the Internet.  One must understand, however, that the globallyGerich                       Informational                      [Page 2]

RFC 1814               Unique Addresses are Good               June 1995   unique address by itself does not necessarily guarantee global   connectivity.  Individual network service providers may place   restrictions on what addresses they will or will not route based on   operational limitations.References   [1] Gerich, E., "Guidelines for Management of IP Address Space",RFC1466, Merit Network Inc., May 1993.   [2] Rekhter, Y., Moskowitz, B., Karrenberg, D., and G. de Groot,       "Address Allocation for Private Internets",RFC 1597, T.J. Watson       Research Center, IBM Corp., Chrysler Corp., RIPE NCC, RIPE NCC,       March 1994.Security Considerations   Security issues are not discussed in this memo.Author's Address   Elise Gerich   Merit Network Inc.   4251 Plymouth Road   Ann Arbor, MI 48105   Phone: +1 313 764 9430   Fax: +1 313 747 3745   EMail: epg@merit.eduGerich                       Informational                      [Page 3]