Network Working Group                                          E. Gerich
Request for Comments: 1814                            Merit Network Inc.
Category: Informational                                        June 1995

                       Unique Addresses are Good

Status 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.


   The IAB suggests that while RFC 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.


   With the advent of RFC 1466 and RFC 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 Registries

   RFC 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 in RFC 1466.

   Internet Registries have agreed to comply with the guidelines
   established by RFC 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.

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RFC 1814               Unique Addresses are Good               June 1995

   The preconditions defined in RFC 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 of RFC 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. Thus RFC 1597 documents a way that private enterprises may
   assure that their networks will remain segregated from the Internet.
   The addresses designated in RFC 1597 should not be routed by the

   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

   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 globally

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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.


   [1] Gerich, E., "Guidelines for Management of IP Address Space", RFC
       1466, 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

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