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Network Working Group                                               IANARequest for Comments: 3330                                September 2002Category: InformationalSpecial-Use IPv4 AddressesStatus of this Memo   This memo provides information for the Internet community.  It does   not specify an Internet standard of any kind.  Distribution of this   memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2002).  All Rights Reserved.Abstract   This document describes the global and other specialized IPv4 address   blocks that have been assigned by the Internet Assigned Numbers   Authority (IANA).  It does not address IPv4 address space assigned to   operators and users through the Regional Internet Registries.  It   also does not address allocations or assignments of IPv6 addresses or   autonomous system numbers.1. Introduction   Throughout its entire history, the Internet has employed a central   Internet Assigned Numbers Authority (IANA) responsible for the   allocation and assignment of various identifiers needed for the   operation of the Internet [RFC1174].  In the case of the IPv4 address   space, the IANA allocates parts of the address space to Regional   Internet Registries according to their established needs.  These   Regional Internet Registries are responsible for the assignment of   IPv4 addresses to operators and users of the Internet within their   regions.   Minor portions of the IPv4 address space have been allocated or   assigned directly by the IANA for global or other specialized   purposes.  These allocations and assignments have been documented in   a variety of RFCs and other documents.  This document is intended to   collect these scattered references.   On an ongoing basis, the IANA has been designated by the IETF to make   assignments in support of the Internet Standards Process [RFC2860].Section 4 of this document describes that assignment process.IANA                         Informational                      [Page 1]

RFC 3330               Special-Use IPv4 Addresses         September 20022. Global and Other Specialized Address Blocks   0.0.0.0/8 - Addresses in this block refer to source hosts on "this"   network.  Address 0.0.0.0/32 may be used as a source address for this   host on this network; other addresses within 0.0.0.0/8 may be used to   refer to specified hosts on this network [RFC1700, page 4].   10.0.0.0/8 - This block is set aside for use in private networks.   Its intended use is documented in [RFC1918].  Addresses within this   block should not appear on the public Internet.   14.0.0.0/8 - This block is set aside for assignments to the   international system of Public Data Networks [RFC1700, page 181]. The   registry of assignments within this block can be accessed from the   "Public Data Network Numbers" link on the web page athttp://www.iana.org/numbers.html.  Addresses within this block are   assigned to users and should be treated as such.   24.0.0.0/8 - This block was allocated in early 1996 for use in   provisioning IP service over cable television systems.  Although the   IANA initially was involved in making assignments to cable operators,   this responsibility was transferred to American Registry for Internet   Numbers (ARIN) in May 2001.  Addresses within this block are assigned   in the normal manner and should be treated as such.   39.0.0.0/8 - This block was used in the "Class A Subnet Experiment"   that commenced in May 1995, as documented in [RFC1797].  The   experiment has been completed and this block has been returned to the   pool of addresses reserved for future allocation or assignment.  This   block therefore no longer has a special use and is subject to   allocation to a Regional Internet Registry for assignment in the   normal manner.   127.0.0.0/8 - This block is assigned for use as the Internet host   loopback address.  A datagram sent by a higher level protocol to an   address anywhere within this block should loop back inside the host.   This is ordinarily implemented using only 127.0.0.1/32 for loopback,   but no addresses within this block should ever appear on any network   anywhere [RFC1700, page 5].   128.0.0.0/16 - This block, corresponding to the numerically lowest of   the former Class B addresses, was initially and is still reserved by   the IANA.  Given the present classless nature of the IP address   space, the basis for the reservation no longer applies and addresses   in this block are subject to future allocation to a Regional Internet   Registry for assignment in the normal manner.IANA                         Informational                      [Page 2]

RFC 3330               Special-Use IPv4 Addresses         September 2002   169.254.0.0/16 - This is the "link local" block.  It is allocated for   communication between hosts on a single link.  Hosts obtain these   addresses by auto-configuration, such as when a DHCP server may not   be found.   172.16.0.0/12 - This block is set aside for use in private networks.   Its intended use is documented in [RFC1918].  Addresses within this   block should not appear on the public Internet.   191.255.0.0/16 - This block, corresponding to the numerically highest   to the former Class B addresses, was initially and is still reserved   by the IANA.  Given the present classless nature of the IP address   space, the basis for the reservation no longer applies and addresses   in this block are subject to future allocation to a Regional Internet   Registry for assignment in the normal manner.   192.0.0.0/24 - This block, corresponding to the numerically lowest of   the former Class C addresses, was initially and is still reserved by   the IANA.  Given the present classless nature of the IP address   space, the basis for the reservation no longer applies and addresses   in this block are subject to future allocation to a Regional Internet   Registry for assignment in the normal manner.   192.0.2.0/24 - This block is assigned as "TEST-NET" for use in   documentation and example code.  It is often used in conjunction with   domain names example.com or example.net in vendor and protocol   documentation.  Addresses within this block should not appear on the   public Internet.   192.88.99.0/24 - This block is allocated for use as 6to4 relay   anycast addresses, according to [RFC3068].   192.168.0.0/16 - This block is set aside for use in private networks.   Its intended use is documented in [RFC1918].  Addresses within this   block should not appear on the public Internet.   198.18.0.0/15 - This block has been allocated for use in benchmark   tests of network interconnect devices.  Its use is documented in   [RFC2544].   223.255.255.0/24 - This block, corresponding to the numerically   highest of the former Class C addresses, was initially and is still   reserved by the IANA.  Given the present classless nature of the IP   address space, the basis for the reservation no longer applies and   addresses in this block are subject to future allocation to a   Regional Internet Registry for assignment in the normal manner.IANA                         Informational                      [Page 3]

RFC 3330               Special-Use IPv4 Addresses         September 2002   224.0.0.0/4 - This block, formerly known as the Class D address   space, is allocated for use in IPv4 multicast address assignments.   The IANA guidelines for assignments from this space are described in   [RFC3171].   240.0.0.0/4 - This block, formerly known as the Class E address   space, is reserved.  The "limited broadcast" destination address   255.255.255.255 should never be forwarded outside the (sub-)net of   the source.  The remainder of this space is reserved for future use.   [RFC1700, page 4]3. Summary Table   Address Block             Present Use                       Reference   ---------------------------------------------------------------------   0.0.0.0/8            "This" Network                 [RFC1700, page 4]   10.0.0.0/8           Private-Use Networks                   [RFC1918]   14.0.0.0/8           Public-Data Networks         [RFC1700, page 181]   24.0.0.0/8           Cable Television Networks                    --   39.0.0.0/8           Reserved but subject                           to allocation                       [RFC1797]   127.0.0.0/8          Loopback                       [RFC1700, page 5]   128.0.0.0/16         Reserved but subject                           to allocation                             --   169.254.0.0/16       Link Local                                   --   172.16.0.0/12        Private-Use Networks                   [RFC1918]   191.255.0.0/16       Reserved but subject                           to allocation                             --   192.0.0.0/24         Reserved but subject                           to allocation                             --   192.0.2.0/24         Test-Net   192.88.99.0/24       6to4 Relay Anycast                     [RFC3068]   192.168.0.0/16       Private-Use Networks                   [RFC1918]   198.18.0.0/15        Network Interconnect                           Device Benchmark Testing            [RFC2544]   223.255.255.0/24     Reserved but subject                           to allocation                             --   224.0.0.0/4          Multicast                              [RFC3171]   240.0.0.0/4          Reserved for Future Use        [RFC1700, page 4]4. Assignments of IPv4 Blocks for New Specialized Uses   The IANA has responsibility for making assignments of protocol   parameters used in the Internet according to the requirements of the   "Memorandum of Understanding Concerning the Technical Work of the   Internet Assigned Numbers Authority" [RFC2860].  Among other things,   [RFC2860] requires that protocol parameters be assigned according toIANA                         Informational                      [Page 4]

RFC 3330               Special-Use IPv4 Addresses         September 2002   the criteria and procedures specified in RFCs, including Proposed,   Draft, and full Internet Standards and Best Current Practice   documents, and any other RFC that calls for IANA assignment.   The domain name and IP address spaces involve policy issues (in   addition to technical issues) so that the requirements of [RFC2860]   do not apply generally to those spaces.  Nonetheless, the IANA is   responsible for ensuring assignments of IPv4 addresses as needed in   support of the Internet Standards Process.  When a portion of the   IPv4 address space is specifically required by an RFC, the technical   requirements (e.g., size, prefix length) for the portion should be   described [RFC2434].  Immediately before the RFC is published, the   IANA will, in consultation with the Regional Internet Registries,   make the necessary assignment and notify the RFC Editor of the   particulars for inclusion in the RFC as published.   As required by [RFC2860], the IANA will also make necessary   experimental assignments of IPv4 addresses, also in consultation with   the Regional Internet Registries.5. Security Considerations   The particular assigned values of special-use IPv4 addresses   cataloged in this document do not directly raise security issues.   However, the Internet does not inherently protect against abuse of   these addresses; if you expect (for instance) that all packets from   the 10.0.0.0/8 block originate within your subnet, all border routers   should filter such packets that originate from elsewhere.  Attacks   have been mounted that depend on the unexpected use of some of these   addresses.6. IANA Considerations   This document describes the IANA's past and current practices and   does not create any new requirements for assignments or allocations   by the IANA.7. References   [RFC1174] Cerf, V., "IAB Recommended Policy on Distributing Internet             Identifier Assignment and IAB Recommended Policy Change to             Internet 'Connected' Status",RFC 1174, August 1990.   [RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2,RFC1700, October 1994.   [RFC1797] IANA, "Class A Subnet Experiment",RFC 1797, April 1995.IANA                         Informational                      [Page 5]

RFC 3330               Special-Use IPv4 Addresses         September 2002   [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.             J., and E. Lear, "Address Allocation for Private             Internets",BCP 5,RFC 1918, February 1996.   [RFC2050] Hubbard, K., Kosters, M., Conrad, D., Karrenberg, D., and             J. Postel, "Internet Registry IP Allocation Guidelines",BCP 12,RFC 2050, November 1996.   [RFC2434] Narten, T., and H. Alvestrand, "Guidelines for Writing an             IANA Considerations Section in RFCs",BCP 26,RFC 2434,             October 1998.   [RFC2544] Bradner, S., and J. McQuaid, "Benchmarking Methodology for             Network Interconnect Devices",RFC 2544, March 1999.   [RFC2860] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of             Understanding Concerning the Technical Work of the Internet             Assigned Numbers Authority",RFC 2860, June 2000.   [RFC3068] Huitema, C., "An Anycast Prefix for 6to4 Relay Routers",RFC 3068, June 2001.   [RFC3171] Albanna, Z., Almeroth, K., Meyer, D., and M. Schipper,             "IANA Guidelines for IPv4 Multicast Address Assignments",BCP 51,RFC 3171, August 2001.   [RFC3232] Reynolds, J. Ed., "Assigned Numbers:RFC 1700 is Replaced             by an On-line Database",RFC 3232, January 2002.8. Acknowledgments   Many people have made comments on draft versions of this document.   The IANA would especially like to thank Scott Bradner, Randy Bush,   and Harald Alvestrand for their constructive feedback and comments.9. Author's Address   Internet Assigned Numbers Authority (IANA)   4676 Admiralty Way, Suite 330   Marina del Rey, CA 90292-6601   Phone: +1 310-823-9358   Fax:   +1 310-823-8649   EMail: iana@iana.orgIANA                         Informational                      [Page 6]

RFC 3330               Special-Use IPv4 Addresses         September 200210.  Full Copyright Statement   Copyright (C) The Internet Society (2002).  All Rights Reserved.   This document and translations of it may be copied and furnished to   others, and derivative works that comment on or otherwise explain it   or assist in its implementation may be prepared, copied, published   and distributed, in whole or in part, without restriction of any   kind, provided that the above copyright notice and this paragraph are   included on all such copies and derivative works.  However, this   document itself may not be modified in any way, such as by removing   the copyright notice or references to the Internet Society or other   Internet organizations, except as needed for the purpose of   developing Internet standards in which case the procedures for   copyrights defined in the Internet Standards process must be   followed, or as required to translate it into languages other than   English.   The limited permissions granted above are perpetual and will not be   revoked by the Internet Society or its successors or assigns.   This document and the information contained herein is provided on an   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.IANA                         Informational                      [Page 7]