Internet Engineering Task Force SIP WG
Internet Draft G. Camarillo
Ericsson
draft-ietf-sip-uri-parameter-reg-02.txt
June 16, 2004
Expires: December 2004
The Internet Assigned Number Authority (IANA) Universal
Resource Identifier (URI) Parameter Registry for the Session
Initiation Protocol (SIP)
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Abstract
This document creates an IANA registry for SIP and SIPS URI
parameters, and their values. It also lists the already existing
parameters to be used as initial values for that registry.
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Table of Contents
1 Introduction ........................................ 3
2 Terminology ......................................... 3
3 Use of the Registry ................................. 3
4 IANA Considerations ................................. 4
4.1 SIP and SIPS URI Parameters Sub-Registry ............ 4
4.2 Registration Policy for SIP and SIPS URI Parameters . 5
5 Security Considerations ............................. 5
6 Acknowledgements .................................... 5
7 Authors' Addresses .................................. 5
8 Normative References ................................ 6
9 Informative References .............................. 6
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1 Introduction
RFC3261 [1] allows new SIP URI and SIPS URI parameters, and new
parameter values to be defined. However, RFC3261 omitted an IANA
registry for them. This document creates such a registry.
RFC 3427 [2] documents the process to extend SIP. This document
updates RFC 3427 by specifying how to define and register new SIP and
SIP URI parameters and their values.
2 Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [3] and
indicate requirement levels for compliant SIP implementations.
3 Use of the Registry
SIP and SIPS URI parameters and values for these parameters MUST be
documented in a standards-track RFC in order to be registered by
IANA. This documentation MUST fully explain the syntax, intended
usage, and semantics of the parameter. The intent of this requirement
is to assure inetroperability 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 [2]
documents concerns with regards to new SIP extensions which
may be damaging towards 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 URI, SIPS URI parameters, or parameter values MUST
register them with IANA as described below.
Registered SIP and SIPS URI parameters and their values are to be
considered "reserved words". In order to preserve interoperability,
registered parameters MUST be used in a manner consistent with that
described in their defining RFC. Implementations MUST NOT utilize
"private" or "locally defined" URI parameters that conflict with
registered parameters.
Note that although unregistered SIP and SIPS URI parameters
may be used in implementations, developers are cautioned
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that usage of such parameters is risky. New SIP and SIPS
URI parameters and new values for them may be registered at
any time, and there is no assurance that these new
registered URI parameters will not conflict with
unregistered parameters currently in use.
Some SIP and SIPS URI parameters only accept a set of predefined
parameter values. For example, a parameter indicating the transport
protocol in use may only accept as valid values the predefined tokens
TCP, UDP, and SCTP. Registering all parameter values for all SIP and
SIPS URI parameters of this type would require a large number of
subregistries. Instead, we have chosen to register URI parameter
values by reference. That is, the entry in the URI parameter registry
for a given URI parameter contains references to the RFCs defining
new values of the parameter. References to RFCs defining parameter
values appear in brackets in the registry.
So, the SIP and SIPS URI parameter registry contains a column that
indicates whether or not each parameter only accepts a set of
predefined values. Implementers of parameters with a "yes" in that
column need to find all the valid parameter values in the RFCs
provided as references.
4 IANA Considerations
Section 27 of RFC 3261 [1] creates an IANA registry for method names,
header field names, warning codes, status codes, and option tags.
This specification instructs the IANA to create a new sub-registry
under http://www.iana.org/assignments/sip-parameters:
o SIP/SIPS URI Parameters
4.1 SIP and SIPS URI Parameters Sub-Registry
New SIP and SIPS URI parameters and new parameter values are
registered by the IANA. When registering a new SIP or SIPS parameter
or a new value for a parameter, the following information MUST be
provided.
o Name of the parameter.
o Whether the parameter only accepts a set of predefined values.
o Reference to the RFC defining the parameter and to any RFC
that defines new values for the parameter. References to RFCs
defining parameter values appear in brackets in the registry.
Table 1 contains the initial values for this sub-registry.
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Parameter Name Predefined Values Reference
____________________________________________
comp Yes RFC 3486
lr No RFC 3261
maddr No RFC 3261
method Yes RFC 3261
transport Yes RFC 3261
ttl No RFC 3261
user Yes RFC 3261
Table 1: IANA SIP and SIPS URI parameter sub-registry
Note that any given parameter name is registered both as a SIP and as
a SIPS URI parameter. Still, some parameters may not apply to one of
the schemes. We have chosen to register any parameter as both SIP and
SIPS URI parameter anyway to avoid having two parameters with the
same name, one applicable to SIP URIs and one to SIPS URIs, but with
different semantics. Implementors are urged to read the parameter
specifications for a detailed description of the semantics of any
parameter.
4.2 Registration Policy for SIP and SIPS URI Parameters
As per the terminology in RFC 2434 [4], the registration policy for
SIP and SIPS URI parameters shall be "Specification Required".
For the purposes of this registry, the parameter for which IANA
registration is requested MUST be defined by a standards-track RFC.
5 Security Considerations
There are no security considerations associated to this document.
6 Acknowledgements
Jonathan Rosenberg, Henning Schulzrinne, Rohan Mahy, Dean Willis, and
Allison Mankin provided useful comments.
7 Authors' Addresses
Gonzalo Camarillo
Ericsson
Advanced Signalling Research Lab.
FIN-02420 Jorvas
Finland
electronic mail: Gonzalo.Camarillo@ericsson.com
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8 Normative References
[1] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. R. Johnston, J.
Peterson, R. Sparks, M. Handley, and E. Schooler, "SIP: session
initiation protocol," RFC 3261, Internet Engineering Task Force, June
2002.
[2] A. Mankin, S. Bradner, R. Mahy, D. Willis, J. Ott, and B. Rosen,
"Change process for the session initiation protocol (SIP)," RFC 3427,
Internet Engineering Task Force, Dec. 2002.
[3] S. Bradner, "Key words for use in RFCs to indicate requirement
levels," RFC 2119, Internet Engineering Task Force, Mar. 1997.
[4] T. Narten and H. Alvestrand, "Guidelines for writing an IANA
considerations section in RFCs," RFC 2434, Internet Engineering Task
Force, Oct. 1998.
9 Informative References
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