The 'sipTrunkingCapability' Link Relation Type
draft-ietf-asap-siptrunkingcapability-link-00

Network Working Group                                         K. Inamdar
Internet-Draft                                              Unaffiliated
Intended status: Standards Track                            S. Narayanan
Expires: 3 April 2023                                            D. Engi
                                                            G. Salgueiro
                                                                   Cisco
                                                       30 September 2022

             The 'sipTrunkingCapability' Link Relation Type
             draft-ietf-asap-siptrunkingcapability-link-00

Abstract

   This specification defines the 'sipTrunkingCapability' link relation
   type that may be used for the retrieval of capabilities and
   configuration requirements from Internet Telephony Service Providers
   (ITSPs).  A Session Initiation Protocol (SIP) trunking capability set
   is defined to allow the transfer of technical requirements needed for
   seamless peering between SIP-based enterprise telephony networks and
   ITSPs where an exchange of parameters and configuration information
   is required.

Status of This Memo

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  The 'sipTrunkingCapability' Link Relation Type  . . . . . . .   3
   4.  Example Usage . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     8.2.  Informative Reference . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   RFC 8288 [RFC8288] defined a way of indicating relationships between
   resources on the Web. This document specifies the
   'sipTrunkingCapability' link relation type according to the rules of
   RFC 8288 [RFC8288].  Links with this relationship type can be used to
   exchange capability information between potential peer devices.  In
   the event that systems require additional parameters and
   configuration to negotiate communication, a well-known URI can be
   utilized to deliver information to potential peers including machine-
   readable instructions and parameters needed for peering.

   The 'sipTrunkingCapability' link relation type may be used on web
   resources hosted by Internet Telephony Service Providers (ITSPs) to
   provide a structured and detailed capability set document.  The
   capability set document encapsulates a set of characteristics of an
   ITSP, which when retrieved by enterprise telephony network devices
   allows for automated establishment of Session Initiation Protocol
   (SIP) trunking between the two telephony networks.

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 BCP 14 [RFC2119]
   [RFC8174] when, and only when, they appear in all capitals, as shown
   here.

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3.  The 'sipTrunkingCapability' Link Relation Type

   A capability set document is hosted via web resources by the ITSP.  A
   unique location of the document can be preconfigured and provided to
   each peer by the ITSP, or a centrally published resource can be used
   that dynamically generates the capability set document based on
   Uniform Resource Identifier(s) [RFC3986] determined by the peering
   device.  The document describes the configuration parameters required
   to successfully establish SIP trunking between an enterprise and
   service provider SIP telephony network.  The capability set document
   SHOULD be composed of structured and machine-readable parameters that
   could be easily converted into configuration data to meet the
   communication requirements of the service provider.  The need for an
   enterprise telephony network to obtain a capability set document from
   an Internet Telephony Service Provider (ITSP) is documented in
   Automatic Peering for SIP Trunks [I-D.ietf-asap-sip-auto-peer].

4.  Example Usage

   This section provides an example of possible use of the
   'sipTrunkingCapability' relation type.  The enterprise network device
   solicits the location of the capability document from the well-known
   URI hosted by the SIP service provider using the WebFinger protocol
   [RFC7033].

      GET /.well-known/webfinger?
         resource=acct%3Atrunkent1456%40example.com&
         rel=sipTrunkingCapability
         HTTP/1.1
      Host: ssp1.example.com

   The capability set location is returned to the source device
   referencing the URI that contains parameters for peering.

     HTTP/1.1 200 OK
     Access-Control-Allow-Origin: *
     Content-Type: application/jrd+json
     {
        "subject" : "acct:trunkent1456@example.com",
        "links" :
        [
           {
              "rel" : "sipTrunkingCapability",
              "href" :"https://capserver.ssp1.com/capserver/capdoc.json"
           }
        ]
     }

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   The ITSP may use an authentication framework such as OAuth 2.0
   [RFC6749] to determine the identity of the enterprise telephony
   network and provide the appropriate capability set document.

5.  IANA Considerations

   IANA is instructed to register the sipTrunkingCapability link
   relation under the "Link Relation Types" Registry, with a reference
   to this document, using the following template:

   Relation Name:  sipTrunkingCapability

   Description:  A capability document that defines parameters or
      configuration requirements for automated peering and communication
      channel negotiation of the Session Initiation Protocol (SIP).

   Reference:  RFCXXXX

      [[NOTE TO RFC EDITOR: Please change XXXX to the number assigned to
      this specification, and remove this paragraph on publication.]]

6.  Security Considerations

   The 'sipTrunkingCapability' relation type is not known to introduce
   any new security issues not already discussed in RFC 8288 [RFC8288]
   for generic use of web linking mechanisms.  However, it is
   recommended to exercise caution when publishing potentially sensitive
   capability information over unencrypted or unauthenticated channels.

7.  Acknowledgements

   This document resulted from the discussions in the ASAP working
   group, especially the detailed and thoughtful comments of Paul Jones,
   Marc Petit-Huguenin, Cullen Jennings, Jonathan Rosenberg, Jon
   Peterson and Chris Wendt.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

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   [RFC8288]  Nottingham, M., "Web Linking", RFC 8288,
              DOI 10.17487/RFC8288, October 2017,
              <https://www.rfc-editor.org/info/rfc8288>.

8.2.  Informative Reference

   [I-D.ietf-asap-sip-auto-peer]
              Inamdar, K., Narayanan, S., and C. Jennings, "Automatic
              Peering for SIP Trunks", October 2021,
              <https://datatracker.ietf.org/doc/html/draft-ietf-asap-
              sip-auto-peer>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,
              <https://www.rfc-editor.org/info/rfc6749>.

   [RFC7033]  Jones, P., Salgueiro, G., Jones, M., and J. Smarr,
              "WebFinger", RFC 7033, DOI 10.17487/RFC7033, September
              2013, <https://www.rfc-editor.org/info/rfc7033>.

Authors' Addresses

   Kaustubh Inamdar
   Unaffiliated
   Email: kaustubh.ietf@gmail.com

   Sreekanth Narayanan
   Cisco
   Email: sreenara@cisco.com

   Derek Engi
   Cisco
   Ann Arbor, MI
   US
   Phone: +1 919 392 7966
   Email: deengi@cisco.com

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   Gonzalo Salgueiro
   Cisco
   7200-12 Kit Creek Rd.
   Research Triangle Park, NC 27709
   US
   Phone: +1 919 392 3266
   Email: gsalguei@cisco.com

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