The 'sip-trunking-capability' Link Relation Type
draft-ietf-asap-siptrunkingcapability-link-04

Network Working Group                                         K. Inamdar
Internet-Draft                                              Unaffiliated
Intended status: Informational                              S. Narayanan
Expires: 29 October 2023                                         D. Engi
                                                            G. Salgueiro
                                                                   Cisco
                                                           27 April 2023

            The 'sip-trunking-capability' Link Relation Type
             draft-ietf-asap-siptrunkingcapability-link-04

Abstract

   This informational document defines the 'sip-trunking-capability'
   link relation type that may be used by an enterprise telephony
   Session Initiation Protocol (SIP) network to retrieve a SIP trunking
   capability set document, which contains the capabilities and
   configuration requirements of an Internet Telephony Service Provider
   (ITSP).  These technical requirements allow for seamless peering
   between SIP-based enterprise telephony networks and the ITSP.

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   This Internet-Draft will expire on 29 October 2023.

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   and restrictions with respect to this document.  Code Components
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  The 'sip-trunking-capability' Link Relation Type  . . . . . .   2
   3.  Example Usage . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   RFC 8288 [RFC8288] defines a way of indicating relationships between
   resources on the Web. This document specifies the 'sip-trunking-
   capability' link relation type according to the rules of RFC 8288.
   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 'sip-trunking-capability' link relation type may be used on web
   resources hosted by ITSPs to provide a structured and detailed
   capability set document.  The capability set document
   [I-D.ietf-asap-sip-auto-peer] encapsulates a set of characteristics
   of an ITSP, which when retrieved by enterprise telephony network
   devices allows for automated establishment of SIP [RFC3261] trunking
   between the two telephony networks.

2.  The 'sip-trunking-capability' 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 capability set document describes the configuration
   parameters required to successfully establish SIP trunking between an
   enterprise and an ITSP network.  The capability set document is

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   composed of structured and machine-readable parameters that can be
   converted into configuration data to meet the communication
   requirements of the ITSP.  The need for an enterprise telephony
   network to obtain a capability set document from an ITSP is
   documented in Automatic Peering for SIP Trunks
   [I-D.ietf-asap-sip-auto-peer].

3.  Example Usage

   This section provides an example of possible use of the 'sip-
   trunking-capability' relation type.  The enterprise network device
   solicits the location of the capability set document from the well-
   known URI hosted by the ITSP using the WebFinger protocol [RFC7033].
   The following examples include line-breaks and indentation for
   clarity.

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

   The capability set document location is returned to the network
   device in the "href" attribute.

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

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

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4.  IANA Considerations

   IANA has registered the 'sip-trunking-capability' link relation under
   the "Link Relation Types" registry, with a reference to this
   document, using the following template:

   Relation Name:  sip-trunking-capability

   Description:  Refers to a capability set 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.]]

5.  Security Considerations

   The 'sip-trunking-capability' relation type is not known to introduce
   any new security issues not already discussed in RFC 8288 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.  Additional
   security recommendations are outlined in the capability set document
   definition.  See [I-D.ietf-asap-sip-auto-peer], Part Security
   Considerations.

6.  Acknowledgements

   This document resulted from the discussions in the ASAP working
   group, especially the detailed and thoughtful comments of Paul Jones,
   Marc Petit-Huguenin, Mark Nottingham, Cullen Jennings, Jonathan
   Rosenberg, Jon Peterson, Chris Wendt, Jean Mahoney, and Murray
   Kucherawy.  Additional thanks to Joe Clarke, Tim Bray, Christopher
   Wood, Dan Romascanu, David Dong, Eric Vyncke, Robert Wilton, and Lars
   Eggert for their reviews and feedback.

7.  References

7.1.  Normative References

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

7.2.  Informative References

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   [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>.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              DOI 10.17487/RFC3261, June 2002,
              <https://www.rfc-editor.org/info/rfc3261>.

   [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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