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Network Working Group                                            E. GrayRequest for Comments: 4548                                 J. RutemillerUpdates:1888,4048                                             EricssonCategory: Standards Track                                     G. Swallow                                                     Cisco Systems, Inc.                                                                May 2006Internet Code Point (ICP) Assignments for NSAP AddressesStatus of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2006).Abstract   This document is intended to accomplish two highly inter-related   tasks: to establish an "initial" Internet Code Point (ICP) assignment   for each of IPv4 and IPv6 address encoding in Network Service Access   Point (NSAP) Addresses, and to recommend an IANA assignment policy   for currently unassigned ICP values.  In the first task, this   document is a partial replacement forRFC 1888 -- particularly forsection 6 of RFC 1888.  In the second task, this document   incorporates wording and specifications from ITU-T Recommendation   X.213 and further recommends that IANA use the "IETF consensus"   assignment policy in making future ICP assignments.Table of Contents1. Introduction ....................................................21.1. Conventions ................................................21.2. Acronyms and Terminology ...................................32. IANA Considerations .............................................33. Initial Allocations and Uses ....................................43.1. IPv4 Address Encoding in an NSAPA ..........................43.2. IPv6 Address Encoding in an NSAPA ..........................54. Security Considerations .........................................65. References ......................................................75.1. Normative References .......................................75.2. Informative References .....................................7Gray, et al.                Standards Track                     [Page 1]

RFC 4548         Internet Code Point (ICP) Assignments          May 20061.  IntroductionSection 6 of RFC 1888 [1888] previously provided for assignment of   the initial Internet Code Point (ICP) value '0' for encoding an IPv6   address in a Network Service Access (or Attachment) Point [NSAP]   address.RFC 1888 also defined multiple means for restricted   encoding of an NSAP address in an IPv6 address.   The meansRFC 1888 defined for encoding NSAP addresses in IPv6   address format was heavily annotated with warnings and limitations   that apply should this encoding be used.  Possibly as a result, these   encodings are not used and appear never to have been used in any IPv6   deployment.  In addition,section 6 contains minor errors.  As a   result of these various considerations,RFC 1888 [1888] has been   obsoleted and declared Historic byRFC 4048 [4048].   It is the belief of the authors of this document that the errors insection 6 of RFC 1888 resulted -- at least in part -- because the   ITU-T specification [X.213] that originally assigned Authority and   Format Identifier (AFI) '35' to IANA was not freely publicized, nor   was it incorporated or explained using the mechanism commonly used in   the IETF, i.e., an RFC.   It is therefore part of the purpose of this document to provide that   explanation.   In addition, because there are other documents that refer to the IPv6   ICP assignment inRFC 1888, it is necessary for the errors insection6 of RFC 1888 to be corrected, irrespective of the RFC's ultimate   status.   Finally, no previous RFC (includingRFC 1888) has ever formalized an   assignment of an IPv4 ICP.  This may have been in part because of a   lack of formal definition of an IANA assignment policy for ICP values   under the IANA-allocated AFI ('35').   This document replacessection 6 of RFC 1888 in defining the ICP for   IPv6 address encoding in an NSAP address, and it formalizes the ICP   assignment for IPv4 address encoding in an NSAP address.1.1.  Conventions   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described inRFC 2119 [2119].Gray, et al.                Standards Track                     [Page 2]

RFC 4548         Internet Code Point (ICP) Assignments          May 20061.2.  Acronyms and Terminology   AFI   - Authority and Format Identifier   BCD   - Binary Coded Decimal   DSP   - Domain Specific Part   IANA  - Internet Assigned Numbers Authority   ICP   - Internet Code Point   IDI   - Initial Domain Identifier   IDP   - Initial Domain Part   IETF  - Internet Engineering Task Force   ISO   - International Organization for Standardization   NSAP  - Network Service Access (or Attachment) Point (often NSAPA)   NSAPA - NSAP Address; 20-Octet Address Format   OSI   - Open Systems Interconnection   RFC   - Request For Comments   WIP   - Work In Progress2.  IANA Considerations   An ITU-T Recommendation [X.213] has allocated two AFIs designating   IANA as the assignment authority.  One of these two AFIs ('34') is   allocated for assignment of NSAPA in Decimal Numeric Format.  This   document does not address allocation for this AFI as it is not clear   what use (if any) can be made of this encoding format at this time.   The other AFI ('35') is to be used for binary encoding except as   noted below.   The NSAPA format consists of an Initial Domain Part (IDP) and Domain   Specific Part (DSP).  The IDP, in turn, consists of an Authority and   Format Identifier (AFI) and an Initial Domain Identifier (IDI).  The   AFI is defined to be a binary octet, and the IDI is defined to be a   four decimal digit number encoded in two octets using Binary Coded   Decimal format.  Each nibble of the IDI is used to represent a   decimal digit, using binary value '0000' through '1001'.   In assigning allocation authority for AFI '35' to IANA, the ITU-T   Recommendation [X.213] specifies that the two-octet IDI will be used   to hold an Internet Code Point (ICP) that, because of the decimal   encoding, MUST be in the decimal range from '0' to '9999'.   The ITU-T recommendation assumes the assignment of ICP '0' (zero) for   IPv6 address encoding in a Network Service Access Point Address   (NSAPA, or often NSAP).  In addition, ITU-T assumed that IANA would   assign an ICP for IPv4 address encoding in an NSAPA and X.213 assumed   that the ICP value for this purpose would be '1'.Gray, et al.                Standards Track                     [Page 3]

RFC 4548         Internet Code Point (ICP) Assignments          May 2006   In an NSAPA, the DSP is the remaining octets after the IDP.  For AFI   '35', this is 17 octets having a format as defined by IANA or as   defined by another party and published with IANA consent.   IANA, as the authority responsible for AFI '35', SHOULD NOT assign an   ICP unless there is a corresponding defined, and published, format at   the time of the code point assignment.   The IANA has assigned the following ICP values:       ICP Value   Address Encoding   Format Definition       ----------  -----------------  ----------------------------          '0'           IPv6RFC 4548, section 3.2          '1'           IPv4RFC 4548, section 3.1   Remaining decimal values '2' through '9999' MUST be assigned on an   IETF consensus basis [2434].3.  Initial Allocations and Uses   This document continues the ICP assignment and format definition as   previously defined inRFC 1888, and it formalizes the allocation of   ICP value '1' for IPv4 encoding and the format to be used.  The   sections below describe the specific IPv4 and IPv6 address encoding   formats.3.1.  IPv4 Address Encoding in an NSAPA   If it is required, for whatever reason, to embed an IPv4 address   inside a 20-octet NSAP address, then the following format MUST be   used.  Note: alignment is an artifact of existing NSAPA usage.   A specific possible use of this embedding is to express an IP address   within the ATM Forum address format.  Another possible use would be   to allow Connectionless Network Protocol (CLNP) packets that   encapsulate IPv4 packets to be routed in a CLNP network using the   IPv4 address architecture.  Several leading octets of the IPv4   address could be used as a CLNP routing prefix.   An NSAPA with an AFI value of '35' and an ICP value of '1' (one)   encodes a 4-octet IPv4 address in the first 4 octets of the DSP.  The   last 13 octets of the DSP are unspecified in this document.  To   maintain compatibility with both NSAP format and IPv4 addressing,   these octets MUST be present, but have no intrinsic significance for   IPv4.  The default values for the unspecified octets is zero.Gray, et al.                Standards Track                     [Page 4]

RFC 4548         Internet Code Point (ICP) Assignments          May 2006       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 0-3  |  AFI = 0x35   |   ICP = 0001                  | IPv4 (octet 0)|      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4-7  |             IPv4 (octets 1-3)                 |               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 8-11 |                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 12-15|                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 16-19|                                                               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   An NSAPA with the IANA AFI code and ICP set to '1' (one) is converted   to an IPv4 address by stripping off the first 3 and the last 13   octets.  If the NSAP-addressed contents are passed to a higher layer,   the last 13 octets SHOULD be presented to the higher layer as well.   If an NSAP address using this encoding is used for routing in an IPv4   routing architecture, only the 4-octet IPv4 address MAY be   considered.3.2.  IPv6 Address Encoding in an NSAPA   If it is required, for whatever reason, to embed an IPv6 address   inside a 20-octet NSAP address, then the following format MUST be   used.  Note: alignment is an artifact of existing NSAPA usage.   A specific possible use of this embedding is to express an IP address   within the ATM Forum address format.  Another possible use would be   to allow CLNP packets that encapsulate IPv6 packets to be routed in a   CLNP network using the IPv6 address architecture.  Several leading   octets of the IPv6 address could be used as a CLNP routing prefix.   An NSAPA with an AFI value of '35' and an ICP value of '0' (zero)   encodes a 16-octet IPv6 address in the first 16 octets of the DSP.   The last octet of the DSP is a selector.  To maintain compatibility   with both NSAP format and IPv6 addressing, this octet MUST be   present, but it has no intrinsic significance for IPv6.  Its default   value is zero, but other values may be used as specified for any   specific application.  For example, this octet may be used to specify   one of 255 possible port numbers.Gray, et al.                Standards Track                     [Page 5]

RFC 4548         Internet Code Point (ICP) Assignments          May 2006       0                   1                   2                   3       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 0-3  |  AFI = 0x35   |   ICP = 0000                  | IPv6 (octet 0)|      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4-7  |             IPv6 (octets 1-4)                                 |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 8-11 |             IPv6 (octets 5-8)                                 |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 12-15|             IPv6 (octets 9-12)                                |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 16-19|       IPv6 (octets 13-15)                     |               |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   An NSAPA with the IANA AFI code and ICP set to '0' (zero) is   converted to an IPv6 address by stripping off the first 3 octets and   the 20th octet.  If the NSAP-addressed contents are passed to a   higher layer, the last octet SHOULD be presented to the higher layer   as well.   If an NSAP address using this encoding is used for routing in an IPv6   routing architecture, only the 16-octet IPv6 address MAY be   considered.4.  Security Considerations   The NSAP encoding of IPv4 and IPv6 addresses is compatible with the   corresponding security mechanisms ofRFC 4301 [4301], hence this   document introduces no new security exposure in the Internet.Gray, et al.                Standards Track                     [Page 6]

RFC 4548         Internet Code Point (ICP) Assignments          May 20065.  References5.1.  Normative References   [4301]  Kent, S. and K. Seo, "Security Architecture for the Internet           Protocol",RFC 4301, December 2005.   [2119]  Bradner, S., "Key words for use in RFCs to Indicate           Requirement Levels",BCP 14,RFC 2119, March 1997.   [NSAP]  International Organization for Standardization, "Information           technology - Open Systems Interconnection - Network service           Definition", ISO/IEC 8348:2002, 2002.   [X.213] ITU-T Recommendation X.213, X-Series Recommendations, Data           Networks and Open Systems Communications, October, 2001.   [2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA           Considerations Section in RFCs",BCP 26,RFC 2434, October           1998.5.2.  Informative References   [1888]  Bound, J., Carpenter, B., Harrington, D., Houldsworth, J.,           and A. Lloyd, "OSI NSAPs and IPv6",RFC 1888, August 1996.   [4048]  Carpenter, B., "RFC 1888 Is Obsolete",RFC 4048, April 2005.Gray, et al.                Standards Track                     [Page 7]

RFC 4548         Internet Code Point (ICP) Assignments          May 2006Authors' Addresses   Eric Gray   Ericsson   900 Chelmsford Street   Lowell, MA, 01851   EMail: Eric.Gray@Marconi.com   John Rutemiller   Ericsson   3000 Marconi Drive   Warrendale, PA, 15086-7502   EMail: John.Rutemiller@Marconi.com   George Swallow   Cisco Systems, Inc.   1414 Massachusetts Avenue   Boxborough, MA, 01719   EMail: swallow@cisco.comGray, et al.                Standards Track                     [Page 8]

RFC 4548         Internet Code Point (ICP) Assignments          May 2006Full Copyright Statement   Copyright (C) The Internet Society (2006).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET   ENGINEERING TASK FORCE DISCLAIM 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.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is provided by the IETF   Administrative Support Activity (IASA).Gray, et al.                Standards Track                     [Page 9]