Internet Assigned Numbers Authority (IANA) Registration of Instant Messaging and Presence DNS SRV RRs for the Session Initiation Protocol (SIP)
draft-loreto-simple-im-srv-label-03

SIMPLE Working Group                                           S. Loreto
Internet-Draft                                                  Ericsson
Intended status: Standards Track                            Jan 15, 2009
Expires: July 19, 2009

   Internet Assigned Numbers Authority (IANA) Registration of Instant
 Messaging and Presence DNS SRV RRs for the Session Initiation Protocol
                                 (SIP)
                  draft-loreto-simple-im-srv-label-03

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Abstract

   This document registers with IANA two new DNS SRV Protocol Labels for
   resolving Instant Messaging and Presence services with SIP.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  DNS SRV usage of SIP with 'im' and 'pres' URIs  . . . . . . . . 3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
     5.1.  Instant Messaging SRV Protocol Label Registration . . . . . 4
     5.2.  Presence SRV Protocol Label Registration  . . . . . . . . . 5
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 6

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1.  Introduction

   The Service Record (SRV) [RFC2782] identifies the host(s) that will
   support particular services.  The DNS is queried for SRV RR in the
   general form:

   _Service._Proto.Name

   Service:  the symbolic name of the desired service.
   Proto:  the protocol of the desired service
   Name:  the domain name for which this record is valid.

   Address Resolution for Instant Messaging and Presence [RFC3861]
   provides guidance for locating the services associated with URIs that
   employ two Uniform Resource Identifier (URI) [RFC3986]: 'im' for
   INSTANT INBOXes [RFC3860] and 'pres' for PRESENTITIES [RFC3859].

   In order to ensure that the association between "_im" and "_pres" and
   their respective underlying services are deterministic, the IANA has
   created two independent registries: the Instant Messaging SRV
   Protocol Label registry and the Presence SRV Protocol Label registry.

   This document defines and registers the "_sip" protocol label in both
   registries so that computer programs can resolve 'im:' and 'pres:'
   URIs down to SIP addresses.

   Moreover this document explains how the SIP usage for Presence and
   Instant Messaging protocol uses SRV.

2.  Terminology

   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 [RFC2119].

3.  DNS SRV usage of SIP with 'im' and 'pres' URIs

   Altough there are standard procedures for resolving im and pres URI
   (section 3 of [RFC3861]), the labels for SIP are not registered.

   Section 5 of [RFC3428] states that if a UA is presented with an IM
   URI (e.g."im:fred@example.com") as the address for an instant
   message, it SHOULD resolve it to a SIP URI, and place the resulting
   URI in the Request-URI of the MESSAGE request before sending".

   Following the procedures defined in [RFC3861], in order to resolve

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   the IM URI the UA performs a SRV lookup for:

   _im._sip.example.com

   Assuming that the example.com domain offers a SIP service for instant
   messaging at simple.example.com, this will result in a resolution of
   _im._sip.example.com. to simple.example.com.  Thus the instant
   messaging URI im:fred@example.com would resolve to a SIP URI of
   sip:fred@simple.example.com.

   Section 5 of [RFC3856] states that procedures defined in [RFC3861]
   are also used to resolve the protocol-independent PRES URI for a
   presentity (e.g. "pres:fred@example.com") into a SIP URI.

   Following the procedures defined in [RFC3861], in order to resolve
   the PRES URI the UA performs a SRV lookup for:

   _pres._sip.example.com

   Assuming that the example.com domain offers a SIP presence service at
   simple.example.com, this will result in a resolution of
   _pres._sip.example.com. to simple.example.com.  Thus the protocol
   independent PRES URI pres:fred@example.com would resolve to a SIP URI
   of sip:fred@simple.example.com.

4.  Security Considerations

   This document merely serves for the registration of DNS SRV labels in
   the appropriate IANA registry.  The document does not specify a
   protocol, therefore, there are no security issues associated with it.

5.  IANA Considerations

   This specification registers a new SRV Protocol Label in each of the
   Instant Messaging SRV Protocol Label registry and the Presence SRV
   Protocol Label registry, respectively.

5.1.  Instant Messaging SRV Protocol Label Registration

   Address Resolution for Instant Messaging and Presence[RFC3861]
   defines an Instant Messaging SRV Protocol Label registry for
   protocols that can provide services that conform to the "_im" SRV
   Service label.  Because SIP is one such protocol, IANA registers the
   "_sip" protocol label in the "Instant Messaging SRV Protocol Label
   Registry", as follows:

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   Protocol label:  _sip
   Specification:  RFCXXXX
   Description:  Instant messaging protocol label for the SIP usage for
      Presence and Instant Messaging protocol as defined by [RFC3428].
   Registrant Contact:  Salvatore Loreto <salvatore.loreto@ericsson.com>

5.2.  Presence SRV Protocol Label Registration

   Address Resolution for Instant Messaging and Presence [RFC3861]
   defines a Presence SRV Protocol Label registry for protocols that can
   provide services that conform to the "_pres" SRV Service label.
   Because SIP usage for Presence and Instant Messaging is one such
   protocol, the IANA registers the "_sip" protocol label in the
   "Presence SRV Protocol Label Registry", as follows:

   Protocol label:  _sip
   Specification:  RFCXXXX
   Description:  Presence protocol label for the SIP usage for Presence
      and Instant Messaging protocol as defined by [RFC3856].
   Registrant Contact:  Salvatore Loreto <salvatore.loreto@ericsson.com>

   Note to RFC editor: Please replace RFCXXXX with the RFC number
   assigned to this document.

6.  Acknowledgments

   The need for this registration was discussed with Jon Peterson and
   Peter Saint-Andre.

   Miguel Garcia reviewed this document on behalf of the Real-time
   Applications and Infrastructure (RAI) Area Review Team (ART).

7.  Normative References

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

   [RFC2782]  Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
              specifying the location of services (DNS SRV)", RFC 2782,
              February 2000.

   [RFC3428]  Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C.,
              and D. Gurle, "Session Initiation Protocol (SIP) Extension
              for Instant Messaging", RFC 3428, December 2002.

   [RFC3856]  Rosenberg, J., "A Presence Event Package for the Session

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              Initiation Protocol (SIP)", RFC 3856, August 2004.

   [RFC3859]  Peterson, J., "Common Profile for Presence (CPP)",
              RFC 3859, August 2004.

   [RFC3860]  Peterson, J., "Common Profile for Instant Messaging
              (CPIM)", RFC 3860, August 2004.

   [RFC3861]  Peterson, J., "Address Resolution for Instant Messaging
              and Presence", RFC 3861, August 2004.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

Author's Address

   Salvatore Loreto
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   Email: Salvatore.Loreto@ericsson.com

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