Internet Engineering Task Force (IETF) D. Romascanu

Internet Engineering Task Force (IETF) D. Romascanu
Request for Comments: 5719 Avaya
Updates: 3588 H. Tschofenig
Category: Standards Track Nokia Siemens Networks
ISSN: 2070-1721 January 2010

Updated IANA Considerations for Diameter Command Code Allocations

Abstract

The Diameter base specification, described in RFC 3588, provides a
number of ways to extend Diameter, with new Diameter commands (i.e.,
messages used by Diameter applications) and applications as the most
extensive enhancements. RFC 3588 illustrates the conditions that
lead to the need to define a new Diameter application or a new
command code. Depending on the scope of the Diameter extension, IETF
actions are necessary. Although defining new Diameter applications
does not require IETF consensus, defining new Diameter commands
requires IETF consensus per RFC 3588. This has led to questionable
design decisions by other Standards Development Organizations, which
chose to define new applications on existing commands -- rather than
asking for assignment of new command codes -- for the pure purpose of
avoiding bringing their specifications to the IETF. In some cases,
interoperability problems were an effect of the poor design caused by
overloading existing commands.

This document aligns the extensibility rules of the Diameter
application with the Diameter commands, offering ways to delegate
work on Diameter to other SDOs to extend Diameter in a way that does
not lead to poor design choices.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc5719.

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RFC 5719 Diameter Command Code Allocation Policy January 2010

Copyright Notice

Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . . 3
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . . 4
6.2. Informative References . . . . . . . . . . . . . . . . . . 5

1. Introduction

The Diameter Base specification, described in [RFC3588], provides a
number of ways to extend Diameter, with new Diameter commands (i.e.,
messages used by Diameter applications) and applications as the most
extensive enhancements. [RFC3588] illustrates the conditions that
require the definition of a new Diameter application or a new
command. Depending on the scope of the Diameter extension, IETF
actions are necessary. Although defining new Diameter applications
does not require IETF consensus, defining new Diameter commands
requires IETF consensus per RFC 3588. This has led to questionable
design decisions by other Standards Development Organizations (SDOs),
which chose to define new applications on existing commands -- rather
than asking for assignment of new command codes -- for the pure
purpose of avoiding bringing their specifications to the IETF. In
some cases, interoperability problems were an effect of poor the
design caused by overloading existing commands.

This document aligns the extensibility rules for Diameter command
codes with those defined for Diameter application identifiers and
offers a consistent way to delegate work on Diameter to other SDOs to
extend Diameter in a way that does not lead to poor design choices.

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RFC 5719 Diameter Command Code Allocation Policy January 2010

This is achieved by splitting the command code space into ranges and
providing different allocation policies to them: the first range is
reserved for RADIUS backward compatibility, allocation of a command
code in the second number range requires IETF review, the third range
is utilized by vendor-specific command codes, and finally the last
range is for experimental commands. Section 4 provides more details
about the command code number ranges, and the different allocation
policies are described in [RFC5226].

A revision of RFC 3588 is currently in development in the IETF DIME
WG [RFC3588bis]; when approved, it will obsolete RFC 3588 as well as
this document. A goal of this document is to provide in advance the
change in the command codes allocation policy, so that
interoperability problems like the ones described above are avoided
as soon as possible.

2. Conventions Used in This Document

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 [RFC2119].

3. Security Considerations

This document modifies the IANA allocation of Diameter command codes
in relationship to RFC 3588. This process change itself does not
raise security concerns, but the command code space is split into a
standard command code space and a vendor-specific command code space,
the latter being allocated on a First Come, First Served basis by
IANA at the request of vendors or other standards organizations.
Whenever work gets delegated to organizations outside the IETF, there
is always the chance that security reviews will be conducted in
different manner and that the criteria and style of those reviews
will be different than the reviews performed in the IETF. The
members of the DIME working group are aware of the risks involved in
using different security and quality review processes and of the
desire to offload work (e.g., to reduce the workload in the IETF) to
other organizations. Other organizations are therefore made
responsible for the quality of the specifications they produce.

4. IANA Considerations

This section describes changes to the IANA Considerations sections
outlined in RFC 3588 regarding the allocation of command codes by
IANA.

The command code namespace is used to identify Diameter commands.
The values 0 - 255 (0x00 - 0xff) are reserved for RADIUS backward

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RFC 5719 Diameter Command Code Allocation Policy January 2010

compatibility and are defined as "RADIUS Packet Type Codes" in
[RADTYPE]. Values 256 - 8,388,607 (0x100 - 0x7fffff) are for
permanent, standard commands allocated by IETF Review [RFC5226].
[RFC3588] defines the command codes 257, 258, 271, 274, 275, 280, and
282; see Section 3.1 in [RFC3588] for the assignment of the namespace
in that specification.

The values 8,388,608 - 16,777,213 (0x800000 - 0xfffffd) are reserved
for vendor-specific command codes, to be allocated on a First Come,
First Served basis by IANA [RFC5226]. The request to IANA for a
vendor-specific command code SHOULD include a reference to a publicly
available specification that documents the command in sufficient
detail to aid in interoperability between independent
implementations. If the specification cannot be made publicly
available, the request for a vendor-specific command code MUST
include the contact information of persons and/or entities
responsible for authoring and maintaining the command.

The values 16,777,214 and 16,777,215 (hexadecimal values 0xfffffe -
0xffffff) are reserved for experimental commands. As these codes are
only for experimental and testing purposes, no guarantee is made for
interoperability between Diameter peers using experimental commands,
as outlined in [RFC3692].

5. Acknowledgements

The content of this document is the result of the work in the IETF
Diameter Maintenance and Extensions (DIME) working group. We would
therefore like to thank all the working group members who were
involved in that discussion. While it appears to be a fairly small
change in the allocation policy, the effect on implementations is
rather dramatic.

We would like to thank Mark Jones for his review comments.

6. References

6.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and
J. Arkko, "Diameter Base Protocol", RFC 3588,
September 2003.

[RFC3692] Narten, T., "Assigning Experimental and Testing Numbers
Considered Useful", BCP 82, RFC 3692, January 2004.

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RFC 5719 Diameter Command Code Allocation Policy January 2010

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing
an IANA Considerations Section in RFCs", BCP 26,
RFC 5226, May 2008.

6.2. Informative References

[RADTYPE] IANA, "Radius Types", <http://www.iana.org>.

[RFC3588bis] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
"Diameter Base Protocol", Work in Progress,
September 2009.

Authors' Addresses

Dan Romascanu
Avaya
Industrial Park Atidim, Bldg#3
Tel Aviv 61581
Israel

Phone: +972-3-645-8414
EMail: [email protected]

Hannes Tschofenig
Nokia Siemens Networks
Linnoitustie 6
Espoo 02600
Finland

Phone: +358 (50) 4871445
EMail: [email protected]
URI: http://www.tschofenig.priv.at

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