ENUM Working Group R. Shockey Internet-Draft NeuStar Intended status: Standards Track T. Creighton Expires: January 8, 2009 Comcast Cable Communications July 7, 2008 IANA Registration for an Enumservice Trunkgroup draft-ietf-enum-trunkgroup-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 8, 2009. Abstract This document registers the Enumservice 'trunk' and subtypes 'sip' and 'tel' using the URI schemes 'sip:' and 'tel:' as per the IANA registration process defined in the ENUM specification RFC 3761 [RFC7761]. RFC 4904 [RFC4904] defines a technique for the conveyance of carrying trunking information in SIP [RFC3261] and or TEL [RFC3966] URI's. This Enumservice provides a mechanism for ENUM databases residing in service provider networks a mechanism to query for that data. Shockey & Creighton Expires January 8, 2009 [Page 1] Internet-Draft Abbreviated Title July 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Definition of Trunking Data . . . . . . . . . . . . . . . . . 4 4. Distribution of Trunkgroup Data . . . . . . . . . . . . . . . 4 5. Enumservice 'trunk' Response Examples . . . . . . . . . . . . 4 5.1. Trunk group in a global number, with a number prefix trunk-context: . . . . . . . . . . . . . . . . . . . . . . 4 6. Implementation Considerations . . . . . . . . . . . . . . . . 5 7. Privacy Considerations . . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 9.1. IANA Enumservice Registration for "trunk" . . . . . . . . 6 9.2. ENUM Service Registration for PSTN with Subtype "sip" . . 6 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 11.1. Normative References . . . . . . . . . . . . . . . . . . . 7 11.2. Informative References . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 10 Shockey & Creighton Expires January 8, 2009 [Page 2] Internet-Draft Abbreviated Title July 2008 1. Introduction ENUM (E.164 Number Mapping), RFC 3761 is a system that transforms E.164 numbers (The International Public Telecommunication Number Plan, ITU-T Recommendation E.164) [Recommendation E.164] into domain names and then uses the Domain Name System (DNS), RFC 1034 [RFC1034] and Naming Authority Pointer Records (NAPTR) records in the Dynamic Delegation Discovery System (DDDS) RFC 3403 [RFC3403] to query the services that are available for a specific domain name. This document registers an Enumservice 'trunk' according to the guidelines given in RFC 3761, to be used for provisioning a NAPTR [RFC3403] resource record to indicate a type of connection associated with an end point and/or telephone number. The registration is defined within the DDDS (Dynamic Delegation Discovery System [RFC3401][RFC3402][RFC3403][RFC3404][RFC3405]) hierarchy, for use with the "E2U" DDDS Application defined in RFC 3761. The service parameters defined in RFC 3761 dictate that a 'type' and one or more 'subtype' should be specified. Within this set of specifications the convention is assumed that the 'type' (being the more generic term) defines the service and at least one of the 'subtype' may indicate the URI scheme. In this document, one type is specified, 'trunk' and two subtypes 'sip' and 'tel' corresponding to the URI scheme specified. RFC 4904 defines the general problem statement as to why sip/tel URI's need to covey trunkgroup parameters. This Enumservice solves the problem of how SIP proxies or other intermediate session routing elements can query for and utilize trunkgroup data. The design of this Enumservice was influenced by several factors: RFC 3761 has become the de facto query-response protocol of for a variety of data types associated with E.164 numbering, addressing and routing. RFC 3761 is already being used by service providers to query for data that has significant privacy or security issues associated with it. RFC 4769 [RFC4769], for instance, describes an Enumservice that associates an E.164 number with a PSTN Local Routing Number. This Enumservice extends that functionality to another form of PSTN routing data. Communications service providers are concerned with the impact of call setup up times on the overall user experience. There is a strong desire to maintain a single query-response mechanism for data Shockey & Creighton Expires January 8, 2009 [Page 3] Internet-Draft Abbreviated Title July 2008 involving E.164 phone numbers and not complicate call processing applications with multiple protocol mechanisms. Were the query for trunkgroup data to require a secondary protocol mechanism such as LDAP or IRIS to retrieve the data, it could significantly impact call setup times. 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. Definition of Trunking Data Trunking data is defined in RFC 4904 as specific circuits in the PSTN that represent a communications paths connecting two switching systems that are used in the establishment of a end to end connection. 4. Distribution of Trunkgroup Data The distribution of trunkgroup data is generally restricted to internal network operations. The NAPTR records described herein SHOULD not be part of the e164.arpa DNS tree. Distribution of this NAPTR data would be either within a service provider's internal network, or on a private basis between one or more parties using a variety of security mechanisms to prohibit general public access. 5. Enumservice 'trunk' Response Examples This section documents several examples of how this protocol is used for illustrative purposes only. From examples given in RFC 4904: 5.1. Trunk group in a global number, with a number prefix trunk- context: tel:+16305550100;tgrp=TG-1;trunk-context=+1-630 Transforming this tel URI to a sip URI yields: sip:+16305550100;tgrp=TG-1;trunk-context=+1-630@ isp.example.net;user=phone Shockey & Creighton Expires January 8, 2009 [Page 4] Internet-Draft Abbreviated Title July 2008 In an ENUM query-response mechanism this data would be presented as follows. $ORIGIN 0.0.1.0.5.5.5.0.3.6.1.enum4.network.net NAPTR 10 100 "u" "E2U+trunk:tel" "!^.*$!tel:+16305550100;tgrp=TG-1;trunk-context=+1-630!". NAPTR 10 50 "u" "E2U+trunk:sip" "!^.*$!sip:+16305550100;tgrp=TG- 1;trunk-context=+1-630@isp.example.net;user=phone!". 6. Implementation Considerations There may be one or more trunkgroups associated with a particular E.164 number since there may be multiple terminations strategies associated with an end-to-end connection. Since an ENUM query for trunkgroup data may return multiple responses, it is important that there be unambiguous information on which group to use or the order to which sessions should be attempted. Implementations of this Enumservice MUST be able to distinguish between the order and preference fields in the NAPTR records. It is recommended that implementers should fix the Order field to a single value (such as 100) and use the preference field to rank order the selections. 7. Privacy Considerations It is assumed that carriers, service providers, or other organizations that originate trunkgroup data will not publish such information in a globally visible DNS tree, such as e164.arpa. This data is strictly for internal service provider use only in highly internally cached ENUM databases, which is only able to be queried by trusted elements of their network, such as soft switches and SIP proxy servers. 8. Security Considerations The trunkgroup Enumservice defined in this document is assumed to be used in an environment where elements are trusted and where attackers are not supposed to have access to the protocol messages between those elements. Traffic protection between network elements is sometimes achieved by using IPSec and sometimes by physically protecting the underlying network. In any case, it is presumed the Shockey & Creighton Expires January 8, 2009 [Page 5] Internet-Draft Abbreviated Title July 2008 environment where the enum trunkgroup request-response mechanism will be used can ensure the integrity and accuracy of the data. 9. IANA Considerations This document registers the 'trunk' Enumservice using the type 'trunk' and the subtypes 'sip' and 'tel' in the Enumservice registry described in the IANA considerations in RFC 3761. 9.1. IANA Enumservice Registration for "trunk" Enumservice Name: "trunk" Enumservice Type: "trunk" Enumservice Subtype: "tel" URI Scheme: 'tel:' Functional Specification: This Enumservices indicate trunkgroup data, as defined in RFC 4904 necessary for a SIP proxy to make routing decisions. Security Considerations: See Section 8. Intended Usage: COMMON Authors: Richard Shockey (richard.shockey@neustar.biz) Tom Creighton (tom_creighton@cable.comcast.com) 9.2. ENUM Service Registration for PSTN with Subtype "sip" Enumservice Name: "pstn" Enumservice Type: "pstn" Enumservice Subtype: "sip" URI Scheme: 'sip:' Functional Specification: These Enumservices indicate that the remote resource identified can be addressed by the associated URI scheme in order to initiate a Shockey & Creighton Expires January 8, 2009 [Page 6] Internet-Draft Abbreviated Title July 2008 telecommunication session, which may include two-way voice or other communications, to the PSTN. Security Considerations: See Section 7. Intended Usage: COMMON Authors: Richard Shockey (richard.shockey@neustar.biz) Tom Creighton (tom_creighton@cable.comcast.com) Interoperability considerations. The URI is designed to be used specifically in conjunction with systems that utilize private the RFC 3761 [ENUM] databases. 10. Acknowledgements 11. References 11.1. Normative References [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC3401] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part One: The Comprehensive DDDS", RFC 3401, October 2002. [RFC3402] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Two: The Algorithm", RFC 3402, October 2002. [RFC3403] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Three: The Domain Name System (DNS) Database", Shockey & Creighton Expires January 8, 2009 [Page 7] Internet-Draft Abbreviated Title July 2008 RFC 3403, October 2002. [RFC3404] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Four: The Uniform Resource Identifiers (URI)", RFC 3404, October 2002. [RFC3405] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Five: URI.ARPA Assignment Procedures", BCP 65, RFC 3405, October 2002. [RFC3761] Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation Discovery System (DDDS) Application (ENUM)", RFC 3761, April 2004. [RFC3966] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966, December 2004. [RFC4769] Livingood, J. and R. Shockey, "IANA Registration for an Enumservice Containing Public Switched Telephone Network (PSTN) Signaling Information", RFC 4769, November 2006. [RFC4904] Gurbani, V. and C. Jennings, "Representing Trunk Groups in tel/sip Uniform Resource Identifiers (URIs)", RFC 4904, June 2007. [Recommendation E.164] ITU-T, "The International Public Telecommunication Number Plan", May 1997. 11.2. Informative References [RFC3833] Atkins, D. and R. Austein, "Threat Analysis of the Domain Name System (DNS)", RFC 3833, August 2004. [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Protocol Modifications for the DNS Security Extensions", RFC 4035, March 2005. Shockey & Creighton Expires January 8, 2009 [Page 8] Internet-Draft Abbreviated Title July 2008 Authors' Addresses Richard Shockey NeuStar 46000 Center Oak Plaza Sterling, VA 20166 USA Phone: +1-571-434-5651 Email: richard.shockey@neustar.biz Tom Creighton Comcast Cable Communications One Comcast Center Philadelphia, PA 19103 USA Phone: +1-215-286-8617 Email: tom_creighton@cable.comcast.com Shockey & Creighton Expires January 8, 2009 [Page 9] Internet-Draft Abbreviated Title July 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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