Network Working Group G. Camarillo
Request for Comments: 3968 Ericsson
Updates: 3427 December 2004
BCP: 98
Category: Best Current Practice
The Internet Assigned Number Authority (IANA)
Header Field Parameter Registry for
the Session Initiation Protocol (SIP)
Status of This Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2004).
Abstract
This document creates an Internet Assigned Number Authority (IANA)
registry for the Session Initiation Protocol (SIP) header field
parameters and parameter values. It also lists the already existing
parameters and parameter values to be used as the initial entries for
this registry.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Use of the Registry . . . . . . . . . . . . . . . . . . . . . 2
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
4.1. Header Field Parameters Sub-Registry . . . . . . . . . . 3
4.2. Registration Policy for SIP Header Field Parameters. . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
7. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7
Full Copyright Statement . . . . . . . . . . . . . . . . . . . 8
Camarillo Best Current Practice [Page 1]
RFC 3968 SIP Parameter Registry December 2004
1. Introduction
RFC 3261 [3] allows new header field parameters and new parameter
values to be defined. However, RFC 3261 omitted an IANA registry for
them. This document creates such a registry.
RFC 3427 [4] documents the process to extend SIP. This document
updates RFC 3427 by specifying how to define and register new SIP
header field parameters and parameter values.
2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
described in BCP 14, RFC 2119 [1] and indicate requirement levels for
compliant implementations.
3. Use of the Registry
SIP header field parameters and parameter values MUST be documented
in an RFC in order to be registered by IANA. This documentation MUST
fully explain the syntax, intended usage, and semantics of the
parameter or parameter value. The intent of this requirement is to
assure interoperability between independent implementations, and to
prevent accidental namespace collisions between implementations of
dissimilar features.
Note that this registry, unlike other protocol registries, only
deals with parameters and parameter values defined in RFCs (i.e.,
it lacks a vendor-extension tree). RFC 3427 [4] documents
concerns with regards to new SIP extensions which may damage
security, greatly increase the complexity of the protocol, or
both. New parameters and parameter values need to be documented
in RFCs as a result of these concerns.
RFCs defining SIP header field parameters or parameter values MUST
register them with IANA as described below.
Registered SIP header field parameters and parameter values are to be
considered "reserved words". In order to preserve interoperability,
registered parameters and parameter values MUST be used in a manner
consistent with that described in their defining RFC.
Implementations MUST NOT utilize "private" or "locally defined" SIP
header field parameters or parameter values that conflict with
registered parameters.
Camarillo Best Current Practice [Page 2]
RFC 3968 SIP Parameter Registry December 2004
Note that although unregistered SIP header field parameters and
parameter values may be used in implementations, developers are
cautioned that usage of such parameters is risky. New SIP header
field parameters and parameter values may be registered at any
datatracker.ietf.org