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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.

Abstract

 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.

Introduction

 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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 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
 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 globally

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 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", 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
 EMail: epg@merit.edu

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