Network Working Group                                         K. Inamdar
Internet-Draft                                              Unaffiliated
Intended status: Standards Track                            S. Narayanan
Expires: 28 September 2022                                       D. Engi
                                                            G. Salgueiro
                                                                   Cisco
                                                              March 2022


             The 'sipTrunkingCapability' Link Relation Type
                draft-engi-siptrunkingcapability-link-00

Abstract

   This specification defines the 'sipTrunkingCapabilities' 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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   This Internet-Draft will expire on 2 September 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   license-info) in effect on the date of publication of this document.



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   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
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   provided without warranty as described in the Revised BSD License.

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 RFC 2119 [RFC2119].






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3.  The 'sipTrunkingCapability' Link Relation Type

   A capability set document is hosted via web resources by the ITSP.
   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 comprised of structured and machine-readable parameters that could
   be easily converted into configuration data to meet the communication
   requirements of the service provider.

4.  Example Usage

   This section provides an example of possible use of the
   'sipTrunkingCapability' relation type.  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].  The
   'sipTrunkingCapability' link relation type allows an enterprise
   telephony network to specifically request the capability set document
   from a web server hosted in the ITSP network.

   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=http%3A%2F%2Fssp1.example.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" : "http://ssp1.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 Oauth2 to
   determine the identity of the enterprise telephony network and
   provide the appropriate capability set document.

5.  IANA Considerations

   IANA has registered 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 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>.

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




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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-04>.

   [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


   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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