Network Working Group Eric Gray
Internet Draft John Rutemiller
Category: Standards Track Marconi Corporation, plc.
Expiration Date: March 2006 George Swallow
Cisco Systems, Inc.
September 2005
Internet Code Point Assignments for NSAP Addresses
draft-gray-rfc1888bis-02
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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 for RFC 1888 - particularly for section 6 of
RFC 1888. In the second task, this document incorporates wording and
specifications from ITU recommendation X.213 and further recommends
that IANA use the "IETF consensus" assignment policy in making future
ICP assignments.
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TABLE OF CONTENTS
1. Introduction .................................................. 2
1.1. Conventions ................................................. 3
1.2. Acronyms and Terminology .................................... 3
2. IANA Considerations ........................................... 3
3. Initial Allocations and Uses .................................. 4
3.1. IPv4 Address Encoding in an NSAPA ........................... 4
3.2. IPv6 Address Encoding in an NSAPA ........................... 5
4. Security Considerations ....................................... 6
5. References .................................................... 6
5.1 Normative References ......................................... 6
5.2 Informative References ....................................... 6
6. Author Information ............................................ 7
7. Copyright Notice .............................................. 7
8. Intellectual Property Notice .................................. 8
9. Acknowledgement ............................................... 8
1. Introduction
Section 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 means RFC 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 by RFC 4048 [4048].
It is the belief of the authors of this document that the errors in
section 6 of RFC 1888 were - at least in part - the result of the
fact that the ITU specification [X.213] that originally assigned
Authority and Format Indentifier (AFI) 35 to IANA was not freely
publicized, nor was it incorporated or explained using the mechanism
commonly used in the IETF - i.e. - via 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 in RFC 1888, it is necessary for the errors in section
6 of RFC 1888 to be corrected - irrespective of the RFC's ultimate
status.
Finally, no previous RFC - including RFC 1888 - has ever formalized
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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 replaces section 6 of RFC 1888 in defining the ICP for
IPv6 address encoding in an NSAP address - and - 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 in RFC 2119 [2119].
1.2. Acronyms and Terminology
AFI - Authority and Format Identifier
BCD - Binary Coded Decimal
DSP - Domain Specific Part
IANA - Internet Assigned Number Authority
ICP - Internet Code Point
IDI - Initial Domain Identifier
IDP - Initial Domain Part
IETF - Internet Engineering Task Force
ISO - International Standardization Organization
NSAP - Network Service Access (or Attachment) Point (often NSAPA)
NSAPA - NSAP Address; 20 Octet Address Format
OSI - Open Systems Interconnect
RFC - Request For Comments
WIP - Work In Progress
2. IANA Considerations
An ITU Recommendation [X.213] has allocated two AFI designating IANA
as the assignment authority. One of these two AFI ('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 - if any
- use 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 four
decimal 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, ITU-T
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[X.213] recommendation specifies that the two octet IDI will be used
to hold an Internet Code Point (ICP) which - because of the decimal
encoding - MUST be in the decimal range from '0' to '9999'.
The ITU recommendation assumes the assignment of ICP '0' (zero) for
IPv6 address encoding in an 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
assumes that the ICP value for this purpose would be '1'.
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 the Authority and Format
Identifier (AFI) '35' - SHOULD NOT assign an ICP unless there is
a corresponding defined, and published, format at the time of the
code point assignment.
As of the time this document is published as an RFC - with consent
of IANA - the following ICP values are assigned:
ICP Value Address Encoding Format Definition
---------- ----------------- ----------------------------
'0' IPv6 <this document>, section 3.2
'1' IPv4 <this document>, 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 in RFC 1888, and 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.
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 IPv4 packets to be routed in a
CLNP network using the IPv4 address architecture. Several leading
bytes of the IPv4 address could be used as a CLNP routing prefix.
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An NSAPA with an AFI value of '35' and an ICP value of '1' (one)
encodes a 4 byte 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.
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 (byte 0)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4-7 | IPv4 (bytes 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 byte 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.
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
bytes 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 byte 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.
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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 (byte 0)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4-7 | IPv6 (bytes 1-4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8-11 | IPv6 (bytes 5-8) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12-15| IPv6 (bytes 9-12) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
16-19| IPv6 (bytes 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 three and the
twentieth octets. 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 byte IPv6 address MAY be
considered.
4. Security Considerations
The NSAP encoding of IPv4 and IPv6 addresses is compatible with the
corresponding security mechanisms of RFC 2401 [2401], hence this
document introduces no new security exposure in the Internet.
5. References
5.1 Normative References
[BCP78] BCP 78/RFC 3667, "IETF Rights in Contributions", Scott
Bradner, February 2004.
[BCP79] BCP 79/RFC 3979, "Intellectual Property Rights in IETF
Technology, Scott Bradner, March 2005.
[2401] RFC 2401, "Security Architecture for the Internet Protocol",
Stephen Kent and Ran Atkinson, November 1998.
[2119] RFC 2119 / BCP 14, "Key words for use in RFCs to Indicate
Requirement Levels", Scott Bradner, March 1997.
[NSAP] International Standardization Organization, "Information
technology - Open Systems Interconnection - Network service
Definition", ISO/IEC 8348:2002, 2002.
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[X.213] ITU-T Recommendation X.213, X-Series Recommendations, Data
Networks and Open Systems Communications, October, 2001.
[2434] RFC 2434, "Guidelines for Writing an IANA Considerations
Section in RFCs", Thomas Narten and Harald Alvestrand,
October 1998.
5.2 Informative References
[1888] RFC 1888, "OSI NSAPs and IPv6", J. Bound, et al, August 1996.
[4048] RFC 4048, "RFC 1888 is Obsolete", Brian Carpenter, April 2005.
6. Author Information
Eric Gray
Marconi Corporation, plc.
900 Chelmsford Street
Lowell, MA, 01851
E-Mail: Eric.Gray@Marconi.com
John Rutemiller
Marconi Corporation, plc.
3000 Marconi Drive
Warrendale, PA, 15086-7502
E-Mail: John.Rutemiller@Marconi.com
George Swallow
Cisco Systems, Inc.
1414 Massachusetts Avenue
Boxborough, MA, 01719
E-Mail: swallow@cisco.com
7. Copyright Notice
Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 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.
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8. Intellectual Property Notice
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 in BCP 78 and BCP 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 at
http://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.
9. Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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Datatracker
draft-gray-rfc1888bis-02
This is an older version of an Internet-Draft that was ultimately published as RFC 4548.
