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RFC 3401 - Dynamic Delegation Discovery System (DDDS) Part One:

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Network Working Group                                        M. Mealling
Request for Comments: 3401                                      VeriSign
Updates: 2276                                               October 2002
Obsoletes: 2915, 2168
Category: Informational

              Dynamic Delegation Discovery System (DDDS)
                    Part One: The Comprehensive DDDS

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.


   This document specifies the exact documents that make up the complete
   Dynamic Delegation Discovery System (DDDS).  DDDS is an abstract
   algorithm for applying dynamically retrieved string transformation
   rules to an application-unique string.

   This document along with RFC 3402, RFC 3403 and RFC 3404 obsolete RFC
   2168 and RFC 2915, as well as updates RFC 2276.

1. Intended Audience

   This document and the documents that it references are intended for
   anyone attempting to implement or understand the generic DDDS
   algorithm, URI Resolution, ENUM telephone number to URI resolution,
   and the NAPTR DNS resource record.  The reader is warned that reading
   one of the documents in this series without reading the others will
   probably lead to misunderstandings and interoperability problems.

2. Introduction

   The Dynamic Delegation Discovery System is used to implement lazy
   binding of strings to data, in order to support dynamically
   configured delegation systems.  The DDDS functions by mapping some
   unique string to data stored within a DDDS Database by iteratively
   applying string transformation rules until a terminal condition is
   reached.  This document defines the entire DDDS by listing the
   documents that make up the complete specification at this time.

   This document along with RFC 3402, RFC 3403 and RFC 3404 obsoletes
   RFC 2168 [8] and RFC 2915 [6], as well as updates RFC 2276 [5].  This
   document will be updated and or obsoleted when changes are made to
   the DDDS specifications.  Thus the reader is strongly encouraged to
   check the IETF RFC repository for any documents that obsoletes or
   updates this one.

3. The Algorithm

   The DDDS algorithm is defined by RFC 3402 [1].  That document defines
   the following DDDS concepts:

   o  The basic DDDS vocabulary.

   o  The algorithm.

   o  The requirements on applications using the algorithm.

   o  The requirements on databases that store DDDS rules.

   RFC 3402 is the actual DDDS Algorithm specification.  But the
   specification by itself is useless without some additional document
   that defines how and why the algorithm is used.  These documents are
   called Applications and do not actually make up part of the DDDS core
   specification.  Applications require databases in which to store
   their Rules.  These databases are called DDDS Databases and are
   usually specified in separate documents.  But again, these Database
   specifications are not included in the DDDS core specification

4. DDDS Applications

   No implementation can begin without an Application specification, as
   this is what provides the concrete instantiation details for the DDDS
   Algorithm.  Without them the DDDS is nothing more than a general
   algorithm.  Application documents define the following:

   o  the Application Unique String (the thing the delegation rules act

   o  the First Well Known Rule (the Rule that says where the process

   o  the list of valid Databases (you can't just use any Database).

   o  the final expected output.

   Some sample Applications are documented in:

   o  "E.164 number and DNS" (RFC 2916) [7].  This Application uses the
      DDDS to map a telephone number to service endpoints such as SIP or

   o  "Dynamic Delegation Discovery System (DDDS) Part Four: The Uniform
      Resource Identifiers (URI) Resolution Application" (RFC 3404) [3].
      This Application uses the DDDS to resolve any URI to a set of
      endpoints or 'resolvers' that can give additional information
      about the URI independent of its particular URI scheme.

5. Currently Standardized Databases

   Any DDDS Application must use some type of DDDS Database.  Database
   documents define the following:

   o  the general spec for how the Database works.

   o  formats for Keys.

   o  formats for Rules.

   o  Key lookup process.

   o  rule insertion procedures.

   o  collision avoidance measures.

   A Database cannot be used on its own; there must be at least one
   Application that uses it.  Multiple Databases and Applications are
   defined, and some Databases will support multiple Applications.
   However, not every Application uses each Database, and vice versa.
   Thus, compliance is defined by the combination of a Database and
   Application specification.

   One sample Database specification is documented in:

   o  "Dynamic Delegation Discovery System (DDDS) Part Three: The Domain
      Name System (DNS) Database" (RFC 3402) [1].  (This document is the
      official specification for the NAPTR DNS Resource Record.)

6. Security Considerations

   Any known security issues that arise from the use of algorithms and
   databases must be specified in the respective specifications.  They
   must be completely and fully described.  It is not required that the
   database and algorithms be secure or that it be free from risks, but

   that the known risks be identified.  Publication of a new database
   type or algorithm does require a security review, and the security
   considerations section should be subject to continuing evaluation.
   Additional security considerations should be addressed by publishing
   revised versions of the database and algorithm specifications.

7. IANA Considerations

   While this document itself does not create any new requirements for
   the IANA, the documents in this series create many varied
   requirements.  The IANA Considerations sections in those documents
   should be reviewed by the IANA to determine the complete set of new
   registries and requirements.  Any new algorithms, databases or
   applications should take great care in what they require the IANA to
   do in the future.


   [1] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
       Two: The Algorithm", RFC 3402, October 2002.

   [2] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
       Three: The Doman Name System (DNS) Database", RFC 3403, October

   [3] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
       Four: The Uniform Resource Identifiers (URI) Resolution
       Application", RFC 3404, October 2002.

   [4] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
       Five: URI.ARPA Assignment Procedures", RFC 3405, October 2002.

   [5] Sollins, K., "Architectural Principles of Uniform Resource Name
       Resolution", RFC 2276, January 1998.

   [6] Mealling, M. and R. Daniel, "The Naming Authority Pointer (NAPTR)
       DNS Resource Record", RFC 2915, August 2000.

   [7] Faltstrom, P., "E.164 number and DNS", RFC 2916, September 2000.

   [8] Daniel, R. and M. Mealling, "Resolution of Uniform Resource
       Identifiers using the Domain Name System", RFC 2168, June 1997.

Author's Address

   Michael Mealling
   21345 Ridgetop Circle
   Sterling, VA  20166

   EMail: michael@neonym.net
   URI:   http://www.verisignlabs.com

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