The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation Discovery System (DDDS) Application for Infrastructure ENUM
draft-ietf-enum-infrastructure-07

ENUM Working Group                                         J. Livingood 
Internet-Draft                             Comcast Cable Communications 
Expires: May 16, 2008                                         P. Pfautz 
Intended Status: Proposed Standard                                 AT&T 
                                                             R. Stastny 
                                                                  Oefeg 
                                                      November 13, 2007 
    
    
              The E.164 to Uniform Resource Identifiers (URI) 
           Dynamic Delegation Discovery System (DDDS) Application for 
                            Infrastructure ENUM 
                     draft-ietf-enum-infrastructure-07 
    
    
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   Copyright (C) The IETF Trust (2007). 
    
    
Abstract 
    
   This document defines the use case for Infrastructure ENUM and 
   proposes its implementation as a parallel namespace to "e164.arpa" as 
   defined in RFC3761, as the long-term solution to the problem of 

 
 
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   allowing carriers to provision DNS records for telephone numbers 
   independently of those provisioned by end users (number assignees). 
    
 
Table of Contents 
    
   1. Terminology....................................................2 
   2. Introduction...................................................2 
   3. Zone Apex for Infrastructure ENUM..............................3 
   4. IANA Considerations............................................3 
   5. Security and Privacy Considerations............................3 
   6. Acknowledgements...............................................4 
   7. References.....................................................4 
      7.1 Normative References.......................................4 
      7.2 Informative References.....................................4 
   Authors' Addresses................................................4 
   Intellectual Property and Copyright Statements....................5 
    
    
1. 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, RFC-2119 [5]. 
    
2. Introduction 
    
   ENUM (E.164 Number Mapping, RFC 3761 [1]) is a system that transforms 
   E.164 numbers [2] into domain names and then uses the DNS (Domain 
   Name Service) [3] to discover NAPTR records that specify what 
   services are available for a specific domain name. 
 
   ENUM as originally defined was based on the end-user opt-in 
   principle.  While this has great potential to foster new services and 
   end-user choice in the long-term, the current requirements for IP-
   based interconnection of Voice over IP (VoIP) domains require the 
   provisioning of large numbers of allocated or served (hosted) numbers 
   of a participating service provider, without the need for individual 
   users to opt-in or not and so that service providers can provision 
   their own ENUM information that is separate, distinct, and likely to 
   be different from what and end-user may provision.  This is 
   particularly important if Infrastructure ENUM is used for number 
   portability applications, for example, which an end-user would be 
   unlikely to be interested in provisioning but which a service 
   provider would likely find essential.   
    
   In addition, while it is possible that service providers could 
   mandate that their users opt-in into e164.arpa through end-user 

 
 
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   contract terms and conditions, there are substantial downsides to 
   such an approach.  Thus, for all these reasons and many others, ENUM 
   for end-user provisioning is ill-suited for use by service providers 
   for the interconnection of VoIP domains. 
    
   As VoIP evolves and becomes pervasive, E.164-addressed telephone 
   calls need not necessarily traverse the Public Switched Telephone 
   Network (PSTN).  Therefore, VoIP service providers have an interest 
   in using ENUM, on a so-called "Infrastructure" basis, to keep VoIP 
   traffic on IP networks on an end-to-end basis, both within and 
   between service provider domains. This requires of means of 
   identifying a VoIP point of interconnection to which calls addressed 
   to a given E.164 number may be delivered and Infrastructure ENUM 
   provides this means.  Calls that can originate and terminate on IP 
   networks, and do not have to traverse the PSTN, will require fewer or 
   no points of transcoding, and can also involve additional IP network 
   services that are not possible on the PSTN, among other benefits.   
    
   Requirements for Infrastructure ENUM are provided in[4].   
 
3. Zone Apex for Infrastructure ENUM 
 
   This document proposes that Infrastructure ENUM be implemented by 
   means of a parallel namespace to e164.arpa dedicated to 
   Infrastructure ENUM, in a domain which is to be determined. Use of a 
   parallel namespace allows carriers and end users to control their 
   ENUM registrations for a number independently without forcing one to 
   work through the other. 
   
   Infrastructure ENUM Tier 2 resource records in the Infrastructure 
   ENUM tree would be controlled by the service provider that is 
   providing services to a given E.164 number, generally referred to in 
   various nations as the "carrier of record" (see [4]).  The definition 
   of a carrier of record for a given E.164 number is a national matter 
   or is defined by the entity controlling the numbering space.  
    
   See also Section 3, Requirements, in [4]. 
    
4. IANA Considerations 
 
   This document contains no requested IANA actions.   
    
   IANA has created a registry for Enumservices as originally specified 
   in RFC 2916 and revised in RFC 3761.  Enumservices registered with 
   IANA are valid for Infrastructure ENUM as well as end-user ENUM.   
    
5. Security and Privacy Considerations 
    

 
 
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   This document proposes a new zone apex for ENUM to meet the 
   requirements of Infrastructure ENUM.  The over-the-network protocol 
   of ENUM is unchanged by the addition of an apex, and as such, the 
   Security considerations of RFC3761 [1] still apply. Specific 
   considerations related to the security of an Infrastructure ENUM apex 
   are given in more detail in Section 4, Security Considerations, in 
   [4]. 
    
   Infrastructure ENUM registrations proposed by this draft 
   should resolve to service provider points of interconnection rather 
   than end user equipment. Service providers need to take appropriate 
   measures to protect their end user customers from unwanted 
   communications as with other types of interconnections.   
    
    
6. Acknowledgements 
    
   The authors wish to thank Lawrence Conroy, Patrik Faltstrom, Michael 
   Haberler, Otmar Lendl, Steve Lind, Alexander Mayrhofer, Jim Reid, and 
   Richard Shockey for their helpful discussion of this draft and the 
   concept of Infrastructure ENUM. 
    
7. References 
    
7.1 Normative References  
    
   [1] Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource 
   Identifiers (URI) Dynamic Delegation Discovery System (DDDS) 
   Application (ENUM)", RFC 3761, April 2004. 
    
   [2] ITU-T, "The International Public Telecommunication Number Plan", 
   Recommendation E.164, February 2005. 
    
   [3] Mockapetris, P., "DOMAIN NAMES - CONCEPTS AND FACILITIES", RFC 
   1034, November 1987. 
    
   [4] Lind, S., Pfautz, P., "Infrastructure ENUM Requirements", draft-
   ietf-enum-infrastructure-enum-reqs-04, May 2007. 
    
   [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement 
   Levels", RFC 2119, March 1997. 
 
7.2 Informative References  
    
   None 
    
Authors' Addresses 
    
   Jason Livingood 
 
 
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   Comcast Cable Communications 
   1500 Market Street 
   Philadelphia, PA 19102 
   USA 
    
   Phone: +1-215-981-7813 
   Email: jason_livingood@cable.comcast.com 
    
    
   Penn Pfautz 
   AT&T 
  200 S. Laurel Ave 
  Middletown, NJ  07748 
  USA 
   
  Phone: +1-732-420-4962 
  Email: ppfautz@att.com 
    
    
   Richard Stastny 
   Oefeg 
   Postbox 147 
   1103 Vienna 
   Austria 
    
   Phone: +43-664-420-4100 
   Email: Richard.stastny@oefeg.at 
    
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