path: root/doc/rfc/rfc7877.txt

Internet Engineering Task Force (IETF)                     K. Cartwright
Request for Comments: 7877                                     V. Bhatia
Category: Standards Track                                            TNS
ISSN: 2070-1721                                                   S. Ali
                                                                 NeuStar
                                                             D. Schwartz
                                                                XConnect
                                                             August 2016


             Session Peering Provisioning Framework (SPPF)

Abstract

   This document specifies the data model and the overall structure for
   a framework to provision Session Establishment Data (SED) into
   Session Data Registries and SIP Service Provider (SSP) data stores.
   The framework is called the "Session Peering Provisioning Framework"
   (SPPF).  The provisioned data is typically used by network elements
   for session establishment.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7877.

















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Copyright Notice

   Copyright (c) 2016 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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   6
   3.  Framework High-Level Design . . . . . . . . . . . . . . . . .   7
     3.1.  Framework Data Model  . . . . . . . . . . . . . . . . . .   7
     3.2.  Time Value  . . . . . . . . . . . . . . . . . . . . . . .  10
     3.3.  Extensibility . . . . . . . . . . . . . . . . . . . . . .  10
   4.  Substrate Protocol Requirements . . . . . . . . . . . . . . .  11
     4.1.  Mandatory Substrate . . . . . . . . . . . . . . . . . . .  11
     4.2.  Connection Oriented . . . . . . . . . . . . . . . . . . .  11
     4.3.  Request and Response Model  . . . . . . . . . . . . . . .  11
     4.4.  Connection Lifetime . . . . . . . . . . . . . . . . . . .  11
     4.5.  Authentication  . . . . . . . . . . . . . . . . . . . . .  12
     4.6.  Authorization . . . . . . . . . . . . . . . . . . . . . .  12
     4.7.  Confidentiality and Integrity . . . . . . . . . . . . . .  12
     4.8.  Near Real Time  . . . . . . . . . . . . . . . . . . . . .  12
     4.9.  Request and Response Sizes  . . . . . . . . . . . . . . .  12
     4.10. Request and Response Correlation  . . . . . . . . . . . .  13
     4.11. Request Acknowledgement . . . . . . . . . . . . . . . . .  13
   5.  Base Framework Data Structures and Response Codes . . . . . .  13
     5.1.  Basic Object Type and Organization Identifiers  . . . . .  13
     5.2.  Various Object Key Types  . . . . . . . . . . . . . . . .  14
       5.2.1.  Generic Object Key Type . . . . . . . . . . . . . . .  14
       5.2.2.  Derived Object Key Types  . . . . . . . . . . . . . .  15
     5.3.  Response Message Types  . . . . . . . . . . . . . . . . .  16
   6.  Framework Data Model Objects  . . . . . . . . . . . . . . . .  18
     6.1.  Destination Group . . . . . . . . . . . . . . . . . . . .  18
     6.2.  Public Identifier . . . . . . . . . . . . . . . . . . . .  19
     6.3.  SED Group . . . . . . . . . . . . . . . . . . . . . . . .  25
     6.4.  SED Record  . . . . . . . . . . . . . . . . . . . . . . .  29
     6.5.  SED Group Offer . . . . . . . . . . . . . . . . . . . . .  33
     6.6.  Egress Route  . . . . . . . . . . . . . . . . . . . . . .  35



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   7.  Framework Operations  . . . . . . . . . . . . . . . . . . . .  36
     7.1.  Add Operation . . . . . . . . . . . . . . . . . . . . . .  37
     7.2.  Delete Operation  . . . . . . . . . . . . . . . . . . . .  37
     7.3.  Get Operations  . . . . . . . . . . . . . . . . . . . . .  38
     7.4.  Accept Operations . . . . . . . . . . . . . . . . . . . .  38
     7.5.  Reject Operations . . . . . . . . . . . . . . . . . . . .  39
     7.6.  Get Server Details Operation  . . . . . . . . . . . . . .  39
   8.  XML Considerations  . . . . . . . . . . . . . . . . . . . . .  40
     8.1.  Namespaces  . . . . . . . . . . . . . . . . . . . . . . .  40
     8.2.  Versioning and Character Encoding . . . . . . . . . . . .  40
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  41
     9.1.  Confidentiality and Authentication  . . . . . . . . . . .  41
     9.2.  Authorization . . . . . . . . . . . . . . . . . . . . . .  41
     9.3.  Denial of Service . . . . . . . . . . . . . . . . . . . .  41
       9.3.1.  DoS Issues Inherited from the Substrate Mechanism . .  42
       9.3.2.  DoS Issues Specific to SPPF . . . . . . . . . . . . .  42
     9.4.  Information Disclosure  . . . . . . . . . . . . . . . . .  43
     9.5.  Non-repudiation . . . . . . . . . . . . . . . . . . . . .  43
     9.6.  Replay Attacks  . . . . . . . . . . . . . . . . . . . . .  43
     9.7.  Compromised or Malicious Intermediary . . . . . . . . . .  44
   10. Internationalization Considerations . . . . . . . . . . . . .  44
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  44
     11.1.  URN Assignments  . . . . . . . . . . . . . . . . . . . .  44
     11.2.  Organization Identifier Namespace Registry . . . . . . .  45
   12. Formal Specification  . . . . . . . . . . . . . . . . . . . .  45
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  54
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  54
     13.2.  Informative References . . . . . . . . . . . . . . . . .  55
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  57
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  57

1.  Introduction

   Service Providers (SPs) and enterprises use routing databases known
   as Registries to make session routing decisions for Voice over IP,
   SMS, and Multimedia Messaging Service (MMS) traffic exchanges.  This
   document is narrowly focused on the provisioning framework for these
   Registries.  This framework prescribes a way for an entity to
   provision session-related data into a Session Peering Provisioning
   Protocol (SPPP) Registry (or "Registry").  The data being provisioned
   can be optionally shared with other participating peering entities.
   The requirements and use cases driving this framework have been
   documented in [RFC6461].

   Three types of provisioning flows have been described in the use case
   document: client to Registry, Registry to local data repository, and
   Registry to Registry.  This document addresses client-to-Registry
   flow enabling the ability to provision Session Establishment Data



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   (SED).  The framework that supports the flow of messages to
   facilitate client-to-Registry provisioning is referred to as the
   "Session Peering Provisioning Framework" (SPPF).

   The roles of the "client" and the "server" only apply to the
   connection, and those roles are not related in any way to the type of
   entity that participates in a protocol exchange.  For example, a
   Registry might also include a "client" when such a Registry initiates
   a connection (for example, for data distribution to an SSP).

   *--------*               *------------*               *------------*
   |        | (1) Client   |             | (3) Registry  |            |
   | Client | ------------> |  Registry  |<------------->|  Registry  |
   |        |   to Registry |            |  to Registry  |            |
   *--------*               *------------*               *------------*
                                 /  \                          \
                                /    \                          \
                               /      \                          \
                              /        \                          v
                             /          \                         ...
                            /            \
                           / (2) Distrib  \
                          / Registry data  \
                         /  to local data   \
                        V      store         V
                       +----------+       +----------+
                       |Local Data|       |Local Data|
                       |Repository|       |Repository|
                       +----------+       +----------+

                Figure 1: Three Registry Provisioning Flows

   A "terminating" SSP provisions SED into the Registry to be
   selectively shared with other peer SSPs.

   SED is typically used by various downstream SIP-signaling systems to
   route a call to the next hop associated with the called domain.
   These systems typically use a local data store ("Local Data
   Repository") as their source of session routing information.  More
   specifically, the SED is the set of parameters that the outgoing
   Signaling Path Border Elements (SBEs) need to initiate the session.
   See [RFC5486] for more details.

   A Registry may distribute the provisioned data into local data
   repositories or may additionally offer a central query-resolution
   service (not shown in the above figure) for query purposes.





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   A key requirement for the SPPF is to be able to accommodate two basic
   deployment scenarios:

   1.  A resolution system returns a Lookup Function (LUF) that
       identifies the target domain to assist in call routing (as
       described in Section 4.3.3 of [RFC5486]).  In this case, the
       querying entity may use other means to perform the Location
       Routing Function (LRF), which in turn helps determine the actual
       location of the Signaling Function in that domain.

   2.  A resolution system returns an LRF that comprises the location
       (address) of the Signaling Function in the target domain (as
       described in [RFC5486]).

   In terms of framework design, SPPF is agnostic to the substrate
   protocol.  This document includes the specification of the data model
   and identifies, but does not specify, the means to enable protocol
   operations within a request and response structure.  That aspect of
   the specification has been delegated to the "protocol" specification
   for the framework.  To encourage interoperability, the framework
   supports extensibility aspects.

   In this document, an XML Schema is used to describe the building
   blocks of the SPPF and to express the data types, semantic
   relationships between the various data types, and various constraints
   as a binding construct.  However, a "protocol" specification is free
   to choose any data representation format as long as it meets the
   requirements laid out in the SPPF XML Schema Definition (XSD).  As an
   example, XML and JSON are two widely used data representation
   formats.

   This document is organized as follows:

   o  Section 2 provides the terminology

   o  Section 3 provides an overview of SPPF, including functional
      entities and a data model

   o  Section 4 specifies requirements for SPPF substrate protocols

   o  Section 5 describes the base framework data structures, the
      generic response types that MUST be supported by a conforming
      substrate "protocol" specification, and the basic object type from
      which most first-class objects extend

   o  Section 6 provides a detailed description of the data model object
      specifications




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   o  Section 7 describes the operations that are supported by the data
      model

   o  Section 8 defines XML considerations XML parsers must meet to
      conform to this specification

   o  Sections 9 - 11 discuss security, internationalization, and IANA
      considerations, respectively

   o  Section 12 normatively defines the SPPF using its XSD.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

   This document reuses terms from [RFC3261], [RFC5486], use cases and
   requirements documented in [RFC6461], and the ENUM Validation
   Architecture [RFC4725].

   This document defines the following additional terms:

   SPPF:   Session Peering Provisioning Framework, which is the
      framework used by a substrate protocol to provision data into a
      Registry (see arrow labeled "1" in Figure 1 of [RFC6461]).  It is
      the primary scope of this document.

   Client:   In the context of SPPF, this is an application that
      initiates a provisioning request.  It is sometimes referred to as
      a "Registry client".

   Server:   In the context of SPPF, this is an application that
      receives a provisioning request and responds accordingly.

   Registry:   The Registry operates a master database of SED for one or
      more Registrants.

   Registrant:   The definition of a Registrant is based on [RFC4725].
      It is the end user, person, or organization that is the "holder"
      of the SED being provisioned into the Registry by a Registrar.
      For example, in [RFC6461], a Registrant is pictured as an SP in
      Figure 2.

      Within the confines of a Registry, a Registrant is uniquely
      identified by the "rant" element.




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   Registrar:   The definition of a Registrar is based on [RFC4725].  It
      is an entity that performs provisioning operations on behalf of a
      Registrant by interacting with the Registry via SPPF operations.
      In other words, the Registrar is the SPPF client.  The Registrar
      and Registrant roles are logically separate to allow, but not
      require, a single Registrar to perform provisioning operations on
      behalf of more than one Registrant.

   Peering Organization:   A peering organization is an entity to which
      a Registrant's SED Groups are made visible using the operations of
      SPPF.

3.  Framework High-Level Design

   This section introduces the structure of the data model and provides
   the information framework for the SPPF.  The data model is defined
   along with all the objects manipulated by a conforming substrate
   protocol and their relationships.

3.1.  Framework Data Model

   The data model illustrated and described in Figure 2 defines the
   logical objects and the relationships between these objects supported
   by SPPF.  SPPF defines protocol operations through which an SPPF
   client populates a Registry with these logical objects.  SPPF clients
   belonging to different Registrars may provision data into the
   Registry using a conforming substrate protocol that implements these
   operations

   The logical structure presented below is consistent with the
   terminology and requirements defined in [RFC6461].




















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       +-------------+                        +-----------------+
       | All object  |                        |Egress Route:    |
       | types       |                   0..n | rant,           |
       +-------------+                     +--| egrRteName,     |
             |0..n                        /   | pref,           |
             |                           /    | regxRewriteRule,|
             |2                         /     | ingrSedGrp,     |
   +----------------------+            /      | svcs            |
   |Organization:         |           /       +-----------------+
   | orgId                |          /
   +----------------------+         /
          |0..n                    /
          |                       /        ("rant" = Registrant)
          |A SED Group is        /
          |associated with      /
          |zero or more        /              +---[abstract]----+
          |peering            /               | SED Record:     |
          |organizations     /                |  rant,          |
          |                 /                 |  sedName,       |0..n
          |0..n            /                  |  sedFunction,   |------|
   +--------+--------------+0..n          0..n|  isInSvc,       |      |
   |SED Group:             |------------------|  ttl            |      |
   |  rant,                |                  +-----------------+      |
   |  sedGrpName,          |                      ^ Various types      |
   |  isInSvc,             |                      | of SED Records     |
   |  sedRecRef,           |                      |                    |
   |  peeringOrg,          |                +-----+------------+       |
   |  sourceIdent,         |                |        |         |       |
   |  priority,            |             +----+  +-------+  +----+     |
   |  dgName               |             | URI|  | NAPTR |  | NS |     |
   +-----------------------+             +----+  +-------+  +----+     |
          |0..n                                                        |
          |                                 +-----[abstract]------+    |
          |0..n                             |Public Identifier:   |    |
      +----------------------+0..n      0..n|  rant,              |    |
      | Dest Group:          |--------------|  publicIdentifier,  |    |
      |   rant,              |              |  dgName             |    |
      |   dgName             |              |                     |    |
      +----------------------+              +---------------------+    |
                                                     ^ Various types   |
                 +---------+-------+------+----------+ of Public       |
                 |         |       |      |          | Identifiers     |
              +------+  +-----+  +-----+ +-----+  +------+             |
              |  URI |  | TNP |  | TNR | | RN  |  |  TN  |-------------|
              +------+  +-----+  +-----+ +-----+  +------+  0..n

                      Figure 2: Framework Data Model




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   The objects and attributes that comprise the data model can be
   described as follows (objects listed from the bottom up):

   o  Public Identifier:
      From a broad perspective, a Public Identifier is a well-known
      attribute that is used as the key to perform resolution lookups.
      Within the context of SPPF, a Public Identifier object can be a
      Telephone Number (TN), a range of TNs, a Public Switched Telephone
      Network (PSTN) Routing Number (RN), a TN prefix, or a URI.

      An SPPF Public Identifier may be a member of zero or more
      Destination Groups to create logical groupings of Public
      Identifiers that share a common set of SED (e.g., routes).

      A TN Public Identifier may optionally be associated with zero or
      more individual SED Records.  This ability for a Public Identifier
      to be directly associated with a SED Record, as opposed to forcing
      membership in one or more Destination Groups, supports use cases
      where the SED Record contains data specifically tailored to an
      individual TN Public Identifier.

   o  Destination Group:
      A named logical grouping of zero or more Public Identifiers that
      can be associated with one or more SED Groups for the purpose of
      facilitating the management of their common SED.

   o  SED Group:
      A SED Group contains a set of SED Record references, a set of
      Destination Group references, and a set of peering organization
      identifiers.  This is used to establish a three-part relationship
      between a set of Public Identifiers, the SED shared across these
      Public Identifiers, and the list of peering organizations whose
      query responses from the resolution system may include the SED
      contained in a given SED Group.  In addition, the sourceIdent
      element within a SED Group, in concert with the set of peering
      organization identifiers, enables fine-grained source-based
      routing.  For further details about the SED Group and source-based
      routing, refer to the definitions and descriptions in Section 6.1.

   o  SED Record:
      A SED Record contains the data that a resolution system returns in
      response to a successful query for a Public Identifier.  SED
      Records are generally associated with a SED Group when the SED
      within is not specific to a Public Identifier.

      To support the use cases defined in [RFC6461], the SPPF defines
      three types of SED Records: URIType, NAPTRType, and NSType.  These
      SED Records extend the abstract type SedRecType and inherit the



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      common attribute "priority" that is meant for setting precedence
      across the SED Records defined within a SED Group in a protocol-
      agnostic fashion.

   o  Egress Route:
      In a high-availability environment, the originating SSP likely has
      more than one egress path to the ingress SBE of the target SSP.
      The Egress Route allows the originating SSP to choose a specific
      egress SBE to be associated with the target ingress SBE.  The
      "svcs" element specifies ENUM services (e.g., E2U+pstn:sip+sip)
      that are used to identify the SED Records associated with the SED
      Group that will be modified by the originating SSP.

   o  Organization:
      An Organization is an entity that may fulfill any combination of
      three roles: Registrant, Registrar, and peering organization.  All
      objects in SPPF are associated with two organization identifiers
      to identify each object's Registrant and Registrar.  A SED Group
      object is also associated with a set of zero or more organization
      identifiers that identify the peering organization(s) whose
      resolution query responses may include the SED defined in the SED
      Records within that SED Group.  A peering organization is an
      entity with which the Registrant intends to share the SED data.

3.2.  Time Value

   Some request and response messages in SPPF include a time value or
   values defined as type xs:dateTime, a built-in W3C XML Schema
   Datatype.  Use of an unqualified local time value is disallowed as it
   can lead to interoperability issues.  The value of a time attribute
   MUST be expressed in Coordinated Universal Time (UTC) format without
   the time-zone digits.

   "2010-05-30T09:30:10Z" is an example of an acceptable time value for
   use in SPPF messages.  "2010-05-30T06:30:10+3:00" is a valid UTC time
   but is not acceptable for use in SPPF messages.

3.3.  Extensibility

   The framework contains various points of extensibility in the form of
   the "ext" elements.  Extensions used beyond the scope of private SPPF
   installations need to be documented in an RFC, and the first such
   extension is expected to define an IANA registry, holding a list of
   documented extensions.







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4.  Substrate Protocol Requirements

   This section provides requirements for substrate protocols suitable
   to carry SPPF.  More specifically, this section specifies the
   services, features, and assumptions that SPPF delegates to the chosen
   substrate and envelope technologies.

4.1.  Mandatory Substrate

   None of the existing transport protocols carried directly over IP,
   appearing as "Protocol" in the IPv4 headers or "Next Header" in the
   IPv6 headers, meet the requirements listed in this section to carry
   SPPF.

   Therefore, one choice to carry SPPF has been provided in "Session
   Peering Provisioning (SPP) Protocol over SOAP" [RFC7878], using SOAP
   as the substrate.  To encourage interoperability, the SPPF server
   MUST provide support for this protocol.  With time, it is possible
   that other choices may surface that comply with the requirements
   discussed above.

4.2.  Connection Oriented

   The SPPF follows a model where a client establishes a connection to a
   server in order to further exchange SPPF messages over such a point-
   to-point connection.  Therefore, a substrate protocol for SPPF will
   be connection oriented.

4.3.  Request and Response Model

   Provisioning operations in SPPF follow the request-response model,
   where a client sends a request message to initiate a transaction and
   the server sends a response.  Multiple subsequent request-response
   exchanges MAY be performed over a single persistent connection.

   Therefore, a substrate protocol for SPPF will follow the request-
   response model by ensuring a response is sent to the request
   initiator.

4.4.  Connection Lifetime

   Some use cases involve provisioning a single request to a network
   element.  Connections supporting such provisioning requests might be
   short-lived, and may be established only on demand, for the duration
   of a few seconds.  Other use cases involve provisioning either a
   large dataset or a constant stream of small updates, both of which
   would likely require long-lived connections, spanning multiple hours
   or even days.



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   Therefore, a protocol suitable for SPPF SHOULD be able to support
   both short-lived and long-lived connections.

4.5.  Authentication

   All SPPF objects are associated with a Registrant identifier.  An
   SPPF client provisions SPPF objects on behalf of Registrants.  An
   authenticated SPP client is a Registrar.  Therefore, the SPPF
   substrate protocol MUST provide means for an SPPF server to
   authenticate an SPPF client.

4.6.  Authorization

   After successful authentication of the SPPF client as a Registrar,
   the Registry performs authorization checks to determine if the
   Registrar is authorized to act on behalf of the Registrant whose
   identifier is included in the SPPF request.  Refer to Section 9 for
   further guidance.

4.7.  Confidentiality and Integrity

   SPPF objects that the Registry manages can be private in nature.
   Therefore, the substrate protocol MUST provide means for data
   integrity protection.

   If the data is compromised in-flight between the SPPF client and
   Registry, it will seriously affect the stability and integrity of the
   system.  Therefore, the substrate protocol MUST provide means for
   data integrity protection.

4.8.  Near Real Time

   Many use cases require responses in near real time from the server
   (in the range of a few multiples of round-trip time between the
   server and client).  Therefore, a Data for Reachability of
   Inter-/Intra-NetworK SIP (DRINKS) substrate protocol MUST support
   near real-time responses to requests submitted by the client.

4.9.  Request and Response Sizes

   Use of SPPF may involve simple updates that may consist of a small
   number of bytes, such as the update of a single Public Identifier.
   Other provisioning operations may constitute a large dataset, as in
   adding millions of records to a Registry.  As a result, a suitable
   substrate protocol for SPPF SHOULD accommodate datasets of various
   sizes.





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4.10.  Request and Response Correlation

   A substrate protocol suitable for SPPF MUST allow responses to be
   correlated with requests.

4.11.  Request Acknowledgement

   Data transported in the SPPF is likely crucial for the operation of
   the communication network that is being provisioned.  An SPPF client
   responsible for provisioning SED to the Registry has a need to know
   if the submitted requests have been processed correctly.

   Failed transactions can lead to situations where a subset of Public
   Identifiers or even SSPs might not be reachable or the provisioning
   state of the network is inconsistent.

   Therefore, a substrate protocol for SPPF MUST provide a response for
   each request, so that a client can identify whether a request
   succeeded or failed.

5.  Base Framework Data Structures and Response Codes

   SPPF contains some common data structures for most of the supported
   object types.  This section describes these common data structures.

5.1.  Basic Object Type and Organization Identifiers

   All first-class objects extend the type BasicObjType.  It consists of
   the Registrant organization, the Registrar organization, the date and
   time of object creation, and the last date and time the object was
   modified.  The Registry MUST store the date and time of the object
   creation and modification, if applicable, for all Get operations (see
   Section 7).  If the client passed in either date or time values, the
   Registry MUST ignore it.  The Registrar performs the SPPF operations
   on behalf of the Registrant, the organization that owns the object.

   <complexType name="BasicObjType" abstract="true">
    <sequence>
     <element name="rant" type="sppfb:OrgIdType"/>
     <element name="rar" type="sppfb:OrgIdType"/>
     <element name="cDate" type="dateTime" minOccurs="0"/>
     <element name="mDate" type="dateTime" minOccurs="0"/>
     <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
    </sequence>
   </complexType>






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   The identifiers used for Registrants (rant) and Registrars (rar) are
   instances of OrgIdType.  The OrgIdType is defined as a string and all
   OrgIdType instances MUST follow the textual convention:
   "namespace:value" (for example, "iana-en:32473").  Specifically:

   Strings used as OrgIdType Namespace identifiers MUST conform to the
   following syntax in the Augmented Backus-Naur Form (ABNF) [RFC5234].

         namespace = ALPHA *(ALPHA/DIGIT/"-")

   See Section 11 for the corresponding IANA registry definition.

5.2.  Various Object Key Types

   The SPPF data model contains various object relationships.  In some
   cases, these object relationships are established by embedding the
   unique identity of the related object inside the relating object.
   Note that an object's unique identity is required to Delete or Get
   the details of an object.  The following subsections normatively
   define the various object keys in SPPF and the attributes of those
   keys.

   "Name" attributes that are used as components of object key types
   MUST be compared using the toCasefold() function, as specified in
   Section 3.13 of [Unicode6.1] (or a newer version of Unicode).  This
   function performs case-insensitive comparisons.

5.2.1.  Generic Object Key Type

   Most objects in SPPF are uniquely identified by an object key that
   has the object's name, type, and Registrant's organization ID as
   attributes.  The abstract type called ObjKeyType is where this unique
   identity is housed.  Any concrete representation of the ObjKeyType
   MUST contain the following:

      Object Name: The name of the object.

      Registrant ID: The unique organization ID that identifies the
      Registrant.

      Type: The value that represents the type of SPPF object.  This is
      required as different types of objects in SPPF, that belong to the
      same Registrant, can have the same name.








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   The structure of abstract ObjKeyType is as follows:

   <complexType name="ObjKeyType" abstract="true">
    <annotation>
     <documentation>
     ---- Generic type that represents the
          key for various objects in SPPF. ----
     </documentation>
    </annotation>
   </complexType>

5.2.2.  Derived Object Key Types

   The SPPF data model contains certain objects that are uniquely
   identified by attributes, different from or in addition to the
   attributes in the generic object key described in the previous
   section.  Object keys of this kind are derived from the abstract
   ObjKeyType and defined in their own abstract key types.  Because
   these object key types are abstract, they MUST be specified in a
   concrete form in any SPPF-conforming substrate "protocol"
   specification.  These are used in Delete and Get operations and may
   also be used in Accept and Reject operations.

   Following are the derived object keys in an SPPF data model:

   o  SedGrpOfferKeyType: This uniquely identifies a SED Group object
      offer.  This key type extends from ObjKeyType and MUST also have
      the organization ID of the Registrant to whom the object is being
      offered as one of its attributes.  In addition to the Delete and
      Get operations, these key types are used in Accept and Reject
      operations on a SED Group Offer object.  The structure of abstract
      SedGrpOfferKeyType is as follows:

   <complexType name="SedGrpOfferKeyType"
   abstract="true">
       <complexContent>
           <extension base="sppfb:ObjKeyType">
               <annotation>
       <documentation>
       ---- Generic type that represents
            the key for an object offer. ----
       </documentation>
      </annotation>
     </extension>
    </complexContent>
   </complexType>





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      A SED Group Offer object MUST use SedGrpOfferKeyType.  Refer to
      Section 6.5 for a description of the SED Group Offer object.

   o  PubIdKeyType: This uniquely identifies a Public Identity object.
      This key type extends from the abstract ObjKeyType.  Any concrete
      definition of PubIdKeyType MUST contain the elements that identify
      the value and type of Public Identity and also contain the
      organization ID of the Registrant that is the owner of the Public
      Identity object.  A Public Identity object in SPPF is uniquely
      identified by the Registrant's organization ID, the value of the
      Public Identity, and the type of the Public Identity object.
      Consequently, any concrete representation of the PubIdKeyType MUST
      contain the following attributes:

      *  Registrant ID: The unique organization ID that identifies the
         Registrant.

      *  Value: The value of the Public Identity.

      *  Type: The type of the Public Identity object.

      The PubIdKeyType is used in Delete and Get operations on a Public
      Identifier object.

   o  The structure of abstract PubIdKeyType is as follows:

   <complexType name="PubIdKeyType" abstract="true">
    <complexContent>
     <extension base="sppfb:ObjKeyType">
      <annotation>
       <documentation>
       ---- Generic type that represents the key for a Pub ID. ----
       </documentation>
      </annotation>
     </extension>
    </complexContent>
   </complexType>

   A Public Identity object MUST use attributes of PubIdKeyType for its
   unique identification.  Refer to Section 6 for a description of a
   Public Identity object.

5.3.  Response Message Types

   The following table contains the list of response types that MUST be
   defined for a substrate protocol used to carry SPPF.  An SPPF server
   MUST implement all of the following at minimum.




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   +---------------------+---------------------------------------------+
   | Response Type       | Description                                 |
   +---------------------+---------------------------------------------+
   | Request succeeded   | A given request succeeded.                  |
   | Request syntax      | The syntax of a given request was found to  |
   | invalid             | be invalid.                                 |
   | Request too large   | The count of entities in the request is     |
   |                     | larger than the server is willing or able   |
   |                     | to process.                                 |
   | Version not         | The server does not support the version of  |
   | supported           | the SPPF protocol specified in the request. |
   | Command invalid     | The operation and/or command being          |
   |                     | requested by the client is invalid and/or   |
   |                     | not supported by the server.                |
   | System temporarily  | The SPPF server is temporarily not          |
   | unavailable         | available to serve the client request.      |
   | Unexpected internal | The SPPF server encountered an unexpected   |
   | system or server    | error that prevented the server from        |
   | error               | fulfilling the request.                     |
   | Attribute value     | The SPPF server encountered an attribute or |
   | invalid             | property in the request that had an         |
   |                     | invalid/bad value.  Optionally, the         |
   |                     | specification MAY provide a way to indicate |
   |                     | the Attribute Name and the Attribute Value  |
   |                     | to identify the object that was found to be |
   |                     | invalid.                                    |
   | Object does not     | An object present in the request does not   |
   | exist               | exist on the SPPF server. Optionally, the   |
   |                     | specification MAY provide a way to indicate |
   |                     | the Attribute Name and the Attribute Value  |
   |                     | that identifies the nonexistent object.     |
   | Object status or    | The operation requested on an object        |
   | ownership does not  | present in the request cannot be performed  |
   | allow for operation | because the object is in a status that does |
   |                     | not allow said operation, or the user       |
   |                     | requesting the operation is not authorized  |
   |                     | to perform said operation on the object.    |
   |                     | Optionally, the specification MAY provide a |
   |                     | way to indicate the Attribute Name and the  |
   |                     | Attribute Value that identifies the object. |
   +---------------------+---------------------------------------------+

                          Table 1: Response Types








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   When the response messages are "parameterized" with the Attribute
   Name and Attribute Value, then the use of these parameters MUST
   adhere to the following rules:

   o  Any value provided for the Attribute Name parameter MUST be an
      exact XSD element name of the protocol data element to which the
      response message is referring.  For example, valid values for
      "attribute name" are "dgName", "sedGrpName", "sedRec", etc.

   o  The value for Attribute Value MUST be the value of the data
      element to which the preceding Attribute Name refers.

   o  Response type "Attribute value invalid" MUST be used whenever an
      element value does not adhere to data validation rules.

   o  Response types "Attribute value invalid" and "Object does not
      exist" MUST NOT be used interchangeably.  Response type "Object
      does not exist" MUST be returned by an Update/Del/Accept/Reject
      operation when the data element(s) used to uniquely identify a
      preexisting object does not exist.  If the data elements used to
      uniquely identify an object are malformed, then response type
      "Attribute value invalid" MUST be returned.

6.  Framework Data Model Objects

   This section provides a description of the specification of each
   supported data model object (the nouns) and identifies the commands
   (the verbs) that MUST be supported for each data model object.
   However, the specification of the data structures necessary to
   support each command is delegated to an SPPF-conforming substrate
   "protocol" specification.

6.1.  Destination Group

   A Destination Group represents a logical grouping of Public
   Identifiers with common SED.  The substrate protocol MUST support the
   ability to Add, Get, and Delete Destination Groups (refer to
   Section 7 for a generic description of various operations).

   A Destination Group object MUST be uniquely identified by attributes
   as defined in the description of "ObjKeyType" in "Generic Object Key
   Type" (Section 5.2.1 of this document).









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   The DestGrpType object structure is defined as follows:

   <complexType name="DestGrpType">
    <complexContent>
     <extension base="sppfb:BasicObjType">
      <sequence>
       <element name="dgName" type="sppfb:ObjNameType"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   The DestGrpType object is composed of the following elements:

   o  base: All first-class objects extend BasicObjType (see
      Section 5.1).

   o  dgName: The character string that contains the name of the
      Destination Group.

   o  ext: Point of extensibility described in Section 3.3.

6.2.  Public Identifier

   A Public Identifier is the search key used for locating the SED.  In
   many cases, a Public Identifier is attributed to the end user who has
   a retail relationship with the SP or Registrant organization.  SPPF
   supports the notion of the carrier-of-record as defined in [RFC5067].
   Therefore, the Registrant under which the Public Identifier is being
   created can optionally claim to be a carrier-of-record.

   SPPF identifies three types of Public Identifiers: TNs, RNs, and
   URIs.  SPPF provides structures to manage a single TN, a contiguous
   range of TNs, and a TN prefix.  The substrate protocol MUST support
   the ability to Add, Get, and Delete Public Identifiers (refer to
   Section 7 for a generic description of various operations).

   A Public Identity object MUST be uniquely identified by attributes as
   defined in the description of "PubIdKeyType" in Section 5.2.2.












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   The abstract XSD type PubIdType is a generalization for the concrete
   Public Identifier schema types.  The PubIdType element "dgName"
   represents the name of a Destination Group of which a given Public
   Identifier may be a member.  Note that this element may be present
   multiple times so that a given Public Identifier may be a member of
   multiple Destination Groups.  The PubIdType object structure is
   defined as follows:

   <complexType name="PubIdType" abstract="true">
    <complexContent>
     <extension base="sppfb:BasicObjType">
      <sequence>
       <element name="dgName" type="sppfb:ObjNameType"
                minOccurs="0" maxOccurs="unbounded"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   A Public Identifier may be a member of zero or more Destination
   Groups.  When a Public Identifier is a member of a Destination Group,
   it is intended to be associated with SED through the SED Group(s)
   that is associated with the Destination Group.  When a Public
   Identifier is not member of any Destination Group, it is intended to
   be associated with SED through the SED Records that are directly
   associated with the Public Identifier.

























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   A TN is provisioned using the TNType, an extension of PubIdType.
   Each TNType object is uniquely identified by the combination of its
   value contained within the <tn> element and its Registrant ID.
   TNType is defined as follows:

   <complexType name="TNType">
    <complexContent>
     <extension base="sppfb:PubIdType">
      <sequence>
       <element name="tn" type="sppfb:NumberValType"/>
       <element name="corInfo" type="sppfb:CORInfoType" minOccurs="0"/>
       <element name="sedRecRef" type="sppfb:SedRecRefType"
                minOccurs="0" maxOccurs="unbounded"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   <complexType name="CORInfoType">
    <sequence>
      <element name="corClaim" type="boolean" default="true"/>
      <element name="cor" type="boolean" default="false" minOccurs="0"/>
      <element name="corDate" type="dateTime" minOccurs="0"/>
    </sequence>
   </complexType>

   <simpleType name="NumberValType">
    <restriction base="token">
     <maxLength value="20"/>
     <pattern value="\+?\d\d*"/>
    </restriction>
   </simpleType>

   TNType consists of the following attributes:

   o  tn: Telephone number to be added to the Registry.

   o  sedRecRef: Optional reference to SED Records that are directly
      associated with the TN Public Identifier.  Following the SPPF data
      model, the SED Record could be a protocol-agnostic URIType or
      another type.

   o  corInfo: corInfo is an optional parameter of type CORInfoType that
      allows the Registrant organization to set forth a claim to be the
      carrier-of-record (see [RFC5067]).  This is done by setting the
      value of the <corClaim> element of the CORInfoType object
      structure to "true".  The other two parameters of the CORInfoType,
      <cor> and <corDate>, are set by the Registry to describe the



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      outcome of the carrier-of-record claim by the Registrant.  In
      general, inclusion of the <corInfo> parameter is useful if the
      Registry has the authority information, such as the number
      portability data, etc., in order to qualify whether the Registrant
      claim can be satisfied.  If the carrier-of-record claim disagrees
      with the authority data in the Registry, whether or not a TN Add
      operation fails is a matter of policy and is beyond the scope of
      this document.

   An RN is provisioned using the RNType, an extension of PubIDType.
   The Registrant organization can add the RN and associate it with the
   appropriate Destination Group(s) to share the route information.
   This allows SSPs to use the RN search key to derive the Ingress
   Routes for session establishment at the runtime resolution process
   (see [RFC6116]).  Each RNType object is uniquely identified by the
   combination of its value inside the <rn> element and its Registrant
   ID.  RNType is defined as follows:

   <complexType name="RNType">
    <complexContent>
     <extension base="sppfb:PubIdType">
      <sequence>
       <element name="rn" type="sppfb:NumberValType"/>
       <element name="corInfo" type="sppfb:CORInfoType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   RNType has the following attributes:

   o  rn: The RN used as the search key.

   o  corInfo: corInfo is an optional parameter of type CORInfoType that
      allows the Registrant organization to set forth a claim to be the
      carrier-of-record (see [RFC5067]).

   TNRType structure is used to provision a contiguous range of TNs.
   The object definition requires a starting TN and an ending TN that
   together define the span of the TN range, including the starting and
   ending TN.  Use of TNRType is particularly useful when expressing a
   TN range that does not include all the TNs within a TN block or
   prefix.  The TNRType definition accommodates the open number plan as
   well such that the TNs that fall in the range between the start and
   end TN may include TNs with different length variance.  Whether the
   Registry can accommodate the open number plan semantics is a matter
   of policy and is beyond the scope of this document.  Each TNRType
   object is uniquely identified by the combination of its value that,



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   in turn, is a combination of the <startTn> and <endTn> elements and
   its Registrant ID.  The TNRType object structure definition is as
   follows:

   <complexType name="TNRType">
    <complexContent>
     <extension base="sppfb:PubIdType">
      <sequence>
       <element name="range" type="sppfb:NumberRangeType"/>
       <element name="corInfo" type="sppfb:CORInfoType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   <complexType name="NumberRangeType">
    <sequence>
     <element name="startTn" type="sppfb:NumberValType"/>
     <element name="endTn" type="sppfb:NumberValType"/>
    </sequence>
   </complexType>

   TNRType has the following attributes:

   o  startTn: The starting TN in the TN range.

   o  endTn: The last TN in the TN range.

   o  corInfo: corInfo is an optional parameter of type CORInfoType that
      allows the Registrant organization to set forth a claim to be the
      carrier-of-record (see [RFC5067]).




















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   In some cases, it is useful to describe a set of TNs with the help of
   the first few digits of the TN, also referred to as the TN prefix or
   a block.  A given TN prefix may include TNs with different length
   variance in support of the open number plan.  Once again, whether the
   Registry supports the open number plan semantics is a matter of
   policy, and it is beyond the scope of this document.  The TNPType
   data structure is used to provision a TN prefix.  Each TNPType object
   is uniquely identified by the combination of its value in the
   <tnPrefix> element and its Registrant ID.  TNPType is defined as
   follows:

   <complexType name="TNPType">
    <complexContent>
     <extension base="sppfb:PubIdType">
      <sequence>
       <element name="tnPrefix" type="sppfb:NumberValType"/>
       <element name="corInfo" type="sppfb:CORInfoType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   TNPType consists of the following attributes:

   o  tnPrefix: The TN prefix.

   o  corInfo: corInfo is an optional parameter of type CORInfoType that
      allows the Registrant organization to set forth a claim to be the
      carrier-of-record (see [RFC5067]).

   In some cases, a Public Identifier may be a URI, such as an email
   address.  The URIPubIdType object is comprised of the data element
   necessary to house such Public Identifiers.  Each URIPubIdType object
   is uniquely identified by the combination of its value in the <uri>
   element and its Registrant ID.  URIPubIdType is defined as follows:

   <complexType name="URIPubIdType">
    <complexContent>
     <extension base="sppfb:PubIdType">
      <sequence>
       <element name="uri" type="anyURI"/>
       <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>





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   URIPubIdType consists of the following attributes:

   o  uri: The value that acts as the Public Identifier.

   o  ext: Point of extensibility described in Section 3.3.

6.3.  SED Group

   SED Group is a grouping of one or more Destination Groups, the common
   SED Records, and the list of peer organizations with access to the
   SED Records associated with a given SED Group.  It is this indirect
   linking of Public Identifiers to their SED that significantly
   improves the scalability and manageability of the peering data.
   Additions and changes to SED information are reduced to a single
   operation on a SED Group or SED Record rather than millions of data
   updates to individual Public Identifier records that individually
   contain their peering data.  The substrate protocol MUST support the
   ability to Add, Get, and Delete SED Groups (refer to Section 7 for a
   generic description of various operations).

   A SED Group object MUST be uniquely identified by attributes as
   defined in the description of "ObjKeyType" in "Generic Object Key
   Type" (Section 5.2.1 of this document).




























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   The SedGrpType object structure is defined as follows:

   <complexType name="SedGrpType">
    <complexContent>
     <extension base="sppfb:BasicObjType">
      <sequence>
       <element name="sedGrpName" type="sppfb:ObjNameType"/>
       <element name="sedRecRef" type="sppfb:SedRecRefType"
                minOccurs="0" maxOccurs="unbounded"/>
       <element name="dgName" type="sppfb:ObjNameType"
                minOccurs="0" maxOccurs="unbounded"/>
       <element name="peeringOrg" type="sppfb:OrgIdType"
                minOccurs="0" maxOccurs="unbounded"/>
       <element name="sourceIdent" type="sppfb:SourceIdentType"
                minOccurs="0" maxOccurs="unbounded"/>
       <element name="isInSvc" type="boolean"/>
       <element name="priority" type="unsignedShort"/>
       <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   <complexType name="SedRecRefType">
    <sequence>
     <element name="sedKey" type="sppfb:ObjKeyType"/>
     <element name="priority" type="unsignedShort"/>
     <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
    </sequence>
   </complexType>

   The SedGrpType object is composed of the following elements:

   o  base: All first-class objects extend BasicObjType (see
      Section 5.1).

   o  sedGrpName: The character string that contains the name of the SED
      Group.  It uniquely identifies this object within the context of
      the Registrant ID (a child element of the base element as
      described above).

   o  sedRecRef: Set of zero or more objects of type SedRecRefType that
      house the unique keys of the SED Records (containing the SED) that
      the SedGrpType object refers to and their relative priority within
      the context of this SED Group.






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   o  dgName: Set of zero or more names of DestGrpType object instances.
      Each dgName name, in association with this SED Group's Registrant
      ID, uniquely identifies a DestGrpType object instance whose
      associated Public Identifiers are reachable using the SED housed
      in this SED Group.  An intended side effect of this is that a SED
      Group cannot provide session establishment information for a
      Destination Group belonging to another Registrant.

   o  peeringOrg: Set of zero or more peering organization IDs that have
      accepted an offer to receive this SED Group's information.  Note
      that this identifier "peeringOrg" is an instance of OrgIdType.
      The set of peering organizations in this list is not directly
      settable or modifiable using the addSedGrpsRqst operation.  This
      set is instead controlled using the SED Offer and Accept
      operations.

   o  sourceIdent: Set of zero or more SourceIdentType object instances.
      These objects, described further below, house the source
      identification schemes and identifiers that are applied at
      resolution time as part of source-based routing algorithms for the
      SED Group.

   o  isInSvc: A boolean element that defines whether this SED Group is
      in service.  The SED contained in a SED Group that is in service
      is a candidate for inclusion in resolution responses for Public
      Identities residing in the Destination Group associated with this
      SED Group.  The session establishment information contained in a
      SED Group that is not in service is not a candidate for inclusion
      in resolution responses.

   o  priority: Priority value that can be used to provide a relative
      value weighting of one SED Group over another.  The manner in
      which this value is used, perhaps in conjunction with other
      factors, is a matter of policy.

   o  ext: Point of extensibility described in Section 3.3.

   As described above, the SED Group contains a set of references to SED
   Record objects.  A SED Record object is based on an abstract type:
   SedRecType.  The concrete types that use SedRecType as an extension
   base are NAPTRType, NSType, and URIType.  The definitions of these
   types are included in "SED Record" (Section 6.4 of this document).

   The SedGrpType object provides support for source-based routing via
   the peeringOrg data element and more granular source-based routing
   via the source identity element.  The source identity element
   provides the ability to specify zero or more of the following in
   association with a given SED Group: a regular expression that is



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   matched against the resolution client IP address, a regular
   expression that is matched against the root domain name(s), and/or a
   regular expression that is matched against the calling party URI(s).
   The result will be that, after identifying the visible SED Groups
   whose associated Destination Group(s) contains the lookup key being
   queried and whose peeringOrg list contains the querying
   organization's organization ID, the resolution server will evaluate
   the characteristics of the Source URI, Source IP address, and root
   domain of the lookup key being queried.  The resolution server then
   compares these criteria against the source identity criteria
   associated with the SED Groups.  The SED contained in SED Groups that
   have source-based routing criteria will only be included in the
   resolution response if one or more of the criteria matches the source
   criteria from the resolution request.  The source identity data
   element is of type SourceIdentType, whose structure is defined as
   follows:

   <complexType name="SourceIdentType">
    <sequence>
     <element name="sourceIdentRegex" type="sppfb:RegexType"/>
     <element name="sourceIdentScheme"
              type="sppfb:SourceIdentSchemeType"/>
     <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
    </sequence>
   </complexType>

   <simpleType name="SourceIdentSchemeType">
    <restriction base="token">
     <enumeration value="uri"/>
     <enumeration value="ip"/>
     <enumeration value="rootDomain"/>
    </restriction>
   </simpleType>

   The SourceIdentType object is composed of the following data
   elements:

   o  sourceIdentScheme: The source identification scheme that this
      source identification criteria applies to and that the associated
      sourceIdentRegex should be matched against.

   o  sourceIdentRegex: The regular expression that should be used to
      test for a match against the portion of the resolution request
      that is dictated by the associated sourceIdentScheme.

   o  ext: Point of extensibility described in Section 3.3.





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6.4.  SED Record

   SED Group represents a combined grouping of SED Records that define
   SED.  However, SED Records need not be created to just serve a single
   SED Group.  SED Records can be created and managed to serve multiple
   SED Groups.  As a result, a change, for example, to the properties of
   a network node used for multiple routes would necessitate just a
   single update operation to change the properties of that node.  The
   change would then be reflected in all the SED Groups whose SED Record
   set contains a reference to that node.  The substrate protocol MUST
   support the ability to Add, Get, and Delete SED Records (refer to
   Section 7 for a generic description of various operations).

   A SED Record object MUST be uniquely identified by attributes as
   defined in the description of "ObjKeyType" in "Generic Object Key
   Type" (Section 5.2.1 of this document).

   The SedRecType object structure is defined as follows:

   <complexType name="SedRecType" abstract="true">
    <complexContent>
     <extension base="sppfb:BasicObjType">
      <sequence>
       <element name="sedName" type="sppfb:ObjNameType"/>
       <element name="sedFunction" type="sppfb:SedFunctionType"
                minOccurs="0"/>
       <element name="isInSvc" type="boolean"/>
       <element name="ttl" type="positiveInteger" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   <simpleType name="SedFunctionType">
    <restriction base="token">
     <enumeration value="routing"/>
     <enumeration value="lookup"/>
    </restriction>
   </simpleType>

   The SedRecType object is composed of the following elements:

   o  base: All first-class objects extend BasicObjType (see
      Section 5.1).







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   o  sedName: The character string that contains the name of the SED
      Record.  It uniquely identifies this object within the context of
      the Registrant ID (a child element of the base element as
      described above).

   o  sedFunction: As described in [RFC6461], SED falls primarily into
      one of two categories or functions: LUF and LRF.  To remove any
      ambiguity as to the function a SED Record is intended to provide,
      this optional element allows the provisioning party to make its
      intentions explicit.

   o  isInSvc: A boolean element that defines whether or not this SED
      Record is in service.  The session establishment information
      contained in a SED Record that is in service is a candidate for
      inclusion in resolution responses for TNs that are either directly
      associated to this SED Record or for Public Identities residing in
      a Destination Group that is associated to a SED Group, which, in
      turn, has an association to this SED Record.

   o  ttl: Number of seconds that an addressing server may cache a
      particular SED Record.

   As described above, SED Records are based on abstract type
   SedRecType.  The concrete types that use SedRecType as an extension
   base are NAPTRType, NSType, and URIType.  The definitions of these
   types are included below.  The NAPTRType object is comprised of the
   data elements necessary for a Naming Authority Pointer (NAPTR) (see
   [RFC3403]) that contains routing information for a SED Group.  The
   NSType object is comprised of the data elements necessary for a DNS
   name server that points to another DNS server that contains the
   desired routing information.  The NSType is relevant only when the
   resolution protocol is ENUM (see [RFC6116]).  The URIType object is
   comprised of the data elements necessary to house a URI.

   The data provisioned in a Registry can be leveraged for many purposes
   and queried using various protocols including SIP, ENUM, and others.
   As such, the resolution data represented by the SED Records must be
   in a form suitable for transport using one of these protocols.  In
   the NAPTRType, for example, if the URI is associated with a
   Destination Group, the user part of the replacement string <uri> that
   may require the Public Identifier cannot be preset.  As a SIP
   Redirect, the resolution server will apply <ere> pattern on the input
   Public Identifier in the query and process the replacement string by
   substituting any back references in the <uri> to arrive at the final
   URI that is returned in the SIP Contact header.  For an ENUM query,
   the resolution server will simply return the values of the <ere> and
   <uri> members of the URI.




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   <complexType name="NAPTRType">
    <complexContent>
     <extension base="sppfb:SedRecType">
      <sequence>
       <element name="order" type="unsignedShort"/>
       <element name="flags" type="sppfb:FlagsType" minOccurs="0"/>
       <element name="svcs" type="sppfb:SvcType"/>
       <element name="regx" type="sppfb:RegexParamType" minOccurs="0"/>
       <element name="repl" type="sppfb:ReplType" minOccurs="0"/>
       <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   <complexType name="NSType">
    <complexContent>
     <extension base="sppfb:SedRecType">
      <sequence>
       <element name="hostName" type="token"/>
       <element name="ipAddr" type="sppfb:IPAddrType"
                minOccurs="0" maxOccurs="unbounded"/>
       <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   <complexType name="IPAddrType">
    <sequence>
     <element name="addr" type="sppfb:AddrStringType"/>
     <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
    </sequence>
    <attribute name="type" type="sppfb:IPType" default="IPv4"/>
   </complexType>

   <simpleType name="IPType">
    <restriction base="token">
     <enumeration value="IPv4"/>
     <enumeration value="IPv6"/>
    </restriction>
   </simpleType>

   <complexType name="URIType">
    <complexContent>
     <extension base="sppfb:SedRecType">
      <sequence>
       <element name="ere" type="token" default="^(.*)$"/>



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       <element name="uri" type="anyURI"/>
       <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   <simpleType name="flagsType">
    <restriction base="token">
     <length value="1"/>
     <pattern value="[A-Z]|[a-z]|[0-9]"/>
    </restriction>
   </simpleType>

   The NAPTRType object is composed of the following elements:

   o  order: Order value in an ENUM NAPTR, relative to other NAPTRType
      objects in the same SED Group.

   o  svcs: ENUM service(s) that is served by the SBE.  This field's
      value must be of the form specified in [RFC6116] (e.g.,
      E2U+pstn:sip+sip).  The allowable values are a matter of policy
      and are not limited by this protocol.

   o  regx: NAPTR's regular expression field.  If this is not included,
      then the repl field must be included.

   o  repl: NAPTR replacement field; it should only be provided if the
      regx field is not provided; otherwise, the server will ignore it.

   o  ext: Point of extensibility described in Section 3.3.

   The NSType object is composed of the following elements:

   o  hostName: Root-relative host name of the name server.

   o  ipAddr: Zero or more objects of type IpAddrType.  Each object
      holds an IP Address and the IP Address type ("IPv4" or "IPv6").

   o  ext: Point of extensibility described in Section 3.3.

   The URIType object is composed of the following elements:

   o  ere: The POSIX Extended Regular Expression (ere) as defined in
      [RFC3986].






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   o  uri: the URI as defined in [RFC3986].  In some cases, this will
      serve as the replacement string, and it will be left to the
      resolution server to arrive at the final usable URI.

6.5.  SED Group Offer

   The list of peer organizations whose resolution responses can include
   the SED contained in a given SED Group is controlled by the
   organization to which a SED Group object belongs (its Registrant) and
   the peer organization that submits resolution requests (a data
   recipient, also known as a peering organization).  The Registrant
   offers access to a SED Group by submitting a SED Group Offer.  The
   data recipient can then accept or reject that offer.  Not until
   access to a SED Group has been offered and accepted will the data
   recipient's organization ID be included in the peeringOrg list in a
   SED Group object, and that SED Group's peering information becomes a
   candidate for inclusion in the responses to the resolution requests
   submitted by that data recipient.  The substrate protocol MUST
   support the ability to Add, Get, Delete, Accept, and Reject SED Group
   Offers (refer to Section 7 for a generic description of various
   operations).

   A SED Group Offer object MUST be uniquely identified by attributes as
   defined in the description of "SedGrpOfferKeyType" in "Derived Object
   Key Types" (Section 5.2.2 of this document).


























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   The SedGrpOfferType object structure is defined as follows:

   <complexType name="SedGrpOfferType">
    <complexContent>
     <extension base="sppfb:BasicObjType">
      <sequence>
       <element name="sedGrpOfferKey" type="sppfb:SedGrpOfferKeyType"/>
       <element name="status" type="sppfb:SedGrpOfferStatusType"/>
       <element name="offerDateTime" type="dateTime"/>
       <element name="acceptDateTime" type="dateTime" minOccurs="0"/>
       <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>

   <complexType name="SedGrpOfferKeyType" abstract="true">
    <annotation>
     <documentation>
     -- Generic type that represents the key for a SED Group Offer. Must
        be defined in concrete form in a substrate "protocol"
        specification. --
     </documentation>
    </annotation>
   </complexType>

   <simpleType name="SedGrpOfferStatusType">
    <restriction base="token">
     <enumeration value="offered"/>
     <enumeration value="accepted"/>
    </restriction>
   </simpleType>

   The SedGrpOfferType object is composed of the following elements:

   o  base: All first-class objects extend BasicObjType (see
      Section 5.1).

   o  sedGrpOfferKey: The object that identifies the SED that is or has
      been offered and the organization to which it is or has been
      offered.

   o  status: The status of the offer, offered or accepted.  The server
      controls the status.  It is automatically set to "offered"
      whenever a new SED Group Offer is added and is automatically set
      to "accepted" if and when that offer is accepted.  The value of
      the element is ignored when passed in by the client.




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   o  offerDateTime: Date and time in UTC when the SED Group Offer was
      added.

   o  acceptDateTime: Date and time in UTC when the SED Group Offer was
      accepted.

6.6.  Egress Route

   In a high-availability environment, the originating SSP likely has
   more than one egress path to the ingress SBE of the target SSP.  If
   the originating SSP wants to exercise greater control and choose a
   specific egress SBE to be associated to the target ingress SBE, it
   can do so using the EgrRteType object.

   An Egress Route object MUST be uniquely identified by attributes as
   defined in the description of "ObjKeyType" in "Generic Object Key
   Type" (Section 5.2.1 of this document).

   Assume that the target SSP has offered, as part of its SED, to share
   one or more Ingress Routes and that the originating SSP has accepted
   the offer.  In order to add the Egress Route to the Registry, the
   originating SSP uses a valid regular expression to rewrite the
   Ingress Route in order to include the egress SBE information.  Also,
   more than one Egress Route can be associated with a given Ingress
   Route in support of fault-tolerant configurations.  The supporting
   SPPF structure provides a way to include route precedence information
   to help manage traffic to more than one outbound egress SBE.

   The substrate protocol MUST support the ability to Add, Get, and
   Delete Egress Routes (refer to Section 7 for a generic description of
   various operations).  The EgrRteType object structure is defined as
   follows:

   <complexType name="EgrRteType">
    <complexContent>
     <extension base="sppfb:BasicObjType">
      <sequence>
       <element name="egrRteName" type="sppfb:ObjNameType"/>
       <element name="pref" type="unsignedShort"/>
       <element name="regxRewriteRule" type="sppfb:RegexParamType"/>
       <element name="ingrSedGrp" type="sppfb:ObjKeyType"
                minOccurs="0" maxOccurs="unbounded"/>
       <element name="svcs" type="sppfb:SvcType" minOccurs="0"/>
       <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
      </sequence>
     </extension>
    </complexContent>
   </complexType>



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   The EgrRteType object is composed of the following elements:

   o  base: All first-class objects extend BasicObjType (see
      Section 5.1).

   o  egrRteName: The name of the Egress Route.

   o  pref: The preference of this Egress Route relative to other Egress
      Routes that may get selected when responding to a resolution
      request.

   o  regxRewriteRule: The regular expression rewrite rule that should
      be applied to the regular expression of the ingress NAPTR(s) that
      belongs to the Ingress Route.

   o  ingrSedGrp: The ingress SED Group that the Egress Route should be
      used for.

   o  svcs: ENUM service(s) that is served by an Egress Route.  This
      element is used to identify the ingress NAPTRs associated with the
      SED Group to which an Egress Route's regxRewriteRule should be
      applied.  If no ENUM service(s) is associated with an Egress
      Route, then the Egress Route's regxRewriteRule should be applied
      to all the NAPTRs associated with the SED Group.  This field's
      value must be of the form specified in [RFC6116] (e.g.,
      E2U+pstn:sip+sip).  The allowable values are a matter of policy
      and are not limited by this protocol.

   o  ext: Point of extensibility described in Section 3.3.

7.  Framework Operations

   In addition to the operation-specific object types, all operations
   MAY specify the minor version of the protocol that when used in
   conjunction with the major version (which can be, for instance,
   specified in the protocol Namespace) can serve to identify the
   version of the SPPF protocol that the client is using.  If the minor
   version is not specified, the latest minor version supported by the
   SPPF server for the given major version will be used.  Additionally,
   operations that may potentially modify persistent protocol objects
   SHOULD include a transaction ID as well.










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7.1.  Add Operation

   Any conforming substrate "protocol" specification MUST provide a
   definition for the operation that adds one or more SPPF objects into
   the Registry.  If the object, as identified by the request attributes
   that form part of the object's key, does not exist, then the Registry
   MUST create the object.  If the object does exist, then the Registry
   MUST replace the current properties of the object with the properties
   passed in as part of the Add operation.

   Note that this effectively allows modification of a preexisting
   object.

   If the entity that issued the command is not authorized to perform
   this operation, an appropriate error message MUST be returned from
   amongst the response messages defined in "Response Message Types"
   (Section 5.3 of this document).

7.2.  Delete Operation

   Any conforming substrate "protocol" specification MUST provide a
   definition for the operation that deletes one or more SPPF objects
   from the Registry using the object's key.

   If the entity that issued the command is not authorized to perform
   this operation, an appropriate error message MUST be returned from
   amongst the response messages defined in "Response Message Types"
   (Section 5.3 of this document).

   When an object is deleted, any references to that object must of
   course also be removed as the SPPF server implementation fulfills the
   deletion request.  Furthermore, the deletion of a composite object
   must also result in the deletion of the objects it contains.  As a
   result, the following rules apply to the deletion of SPPF object
   types:

   o  Destination Groups: When a Destination Group is deleted, any
      cross-references between that destination group and any SED Group
      must be automatically removed by the SPPF implementation as part
      of fulfilling the deletion request.  Similarly, any cross-
      references between that Destination Group and any Public
      Identifier must be removed by the SPPF implementation.

   o  SED Groups: When a SED Group is deleted, any references between
      that SED Group and any Destination Group must be automatically
      removed by the SPPF implementation as part of fulfilling the
      deletion request.  Similarly, any cross-references between that
      SED Group and any SED Records must be removed by the SPPF



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      implementation as part of fulfilling the deletion request.
      Furthermore, SED Group Offers relating to that SED Group must also
      be deleted.

   o  SED Records: When a SED Record is deleted, any cross-references
      between that SED Record and any SED Group must be removed by the
      SPPF implementation as part of fulfilling the deletion request.
      Similarly, any reference between that SED Record and any Public
      Identifier must be removed by the SPPF implementation.

   o  Public Identifiers: When a Public Identifier is deleted, any
      cross-references between that Public Identifier and any referenced
      Destination Group must be removed by the SPPF implementation as
      part of fulfilling the deletion request.  Any references to SED
      Records associated directly to that Public Identifier must also be
      deleted by the SPPF implementation.

   Deletes MUST be atomic.

7.3.  Get Operations

   At times, on behalf of the Registrant, the Registrar may need to get
   information about SPPF objects that were previously provisioned in
   the Registry.  A few examples include logging, auditing, and pre-
   provisioning dependency checking.  This query mechanism is limited to
   aid provisioning scenarios and should not be confused with query
   protocols provided as part of the resolution system (e.g., ENUM and
   SIP).

   Any conforming "protocol" specification MUST provide a definition for
   the operation that queries the details of one or more SPPF objects
   from the Registry using the object's key.  If the entity that issued
   the command is not authorized to perform this operation, an
   appropriate error message MUST be returned from among the response
   messages defined in Section 5.3.

   If the response to the Get operation includes an object(s) that
   extends the BasicObjType, the Registry MUST include the "cDate" and
   "mDate", if applicable.

7.4.  Accept Operations

   In SPPF, a SED Group Offer can be accepted or rejected by, or on
   behalf of, the Registrant to which the SED Group has been offered
   (refer to Section 6.5 of this document for a description of the SED
   Group Offer object).  The Accept operation is used to accept the SED
   Group Offers.  Any conforming substrate "protocol" specification MUST
   provide a definition for the operation to accept SED Group Offers by,



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   or on behalf of, the Registrant, using the SED Group Offer object
   key.

   Not until access to a SED Group has been offered and accepted will
   the Registrant's organization ID be included in the peeringOrg list
   in that SED Group object, and that SED Group's peering information
   becomes a candidate for inclusion in the responses to the resolution
   requests submitted by that Registrant.  A SED Group Offer that is in
   the "offered" status is accepted by, or on behalf of, the Registrant
   to which it has been offered.  When the SED Group Offer is accepted,
   the SED Group Offer is moved to the "accepted" status and the data
   recipient's organization ID is added into the list of peerOrgIds for
   that SED Group.

   If the entity that issued the command is not authorized to perform
   this operation, an appropriate error message MUST be returned from
   amongst the response messages defined in "Response Message Types"
   (Section 5.3 of this document).

7.5.  Reject Operations

   In SPPF, a SED Group Offer object can be accepted or rejected by, or
   on behalf of, the Registrant to which the SED Group has been offered
   (refer to "Framework Data Model Objects", Section 6 of this document,
   for a description of the SED Group Offer object).  Furthermore, that
   offer may be rejected, regardless of whether or not it has been
   previously accepted.  The Reject operation is used to reject the SED
   Group Offer.  When the SED Group Offer is rejected, that SED Group
   Offer is deleted, and, if appropriate, the data recipient's
   organization ID is removed from the list of peeringOrg IDs for that
   SED Group.  Any conforming substrate "protocol" specification MUST
   provide a definition for the operation to reject SED Group Offers by,
   or on behalf of, the Registrant, using the SED Group Offer object
   key.

   If the entity that issued the command is not authorized to perform
   this operation, an appropriate error message MUST be returned from
   among the response messages defined in "Response Message Types"
   (Section 5.3 of this document).

7.6.  Get Server Details Operation

   In SPPF, the Get Server Details operation can be used to request
   certain details about the SPPF server that include the SPPF server's
   current status and the major/minor version of the SPPF protocol
   supported by the SPPF server.





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   Any conforming substrate "protocol" specification MUST provide a
   definition for the operation to request such details from the SPPF
   server.  If the entity that issued the command is not authorized to
   perform this operation, an appropriate error message MUST be returned
   from among the response messages defined in "Response Message Types"
   (Section 5.3 of this document).

8.  XML Considerations

   XML serves as the encoding format for SPPF, allowing complex
   hierarchical data to be expressed in a text format that can be read,
   saved, and manipulated with both traditional text tools and tools
   specific to XML.

   XML is case sensitive.  Unless stated otherwise, the character casing
   of XML specifications in this document MUST be preserved to develop a
   conforming specification.

   This section discusses a small number of XML-related considerations
   pertaining to SPPF.

8.1.  Namespaces

   All SPPF elements are defined in the Namespaces in the "IANA
   Considerations" and "Formal Framework Specification" sections of this
   document.

8.2.  Versioning and Character Encoding

   All XML instances SHOULD begin with an <?xml?> declaration to
   identify the version of XML that is being used, optionally identify
   use of the character encoding used, and optionally provide a hint to
   an XML parser that an external schema file is needed to validate the
   XML instance.

   Conformant XML parsers recognize both UTF-8 (defined in [RFC3629])
   and UTF-16 (defined in [RFC2781]); per [RFC2277], UTF-8 is the
   RECOMMENDED character encoding for use with SPPF.

   Character encodings other than UTF-8 and UTF-16 are allowed by XML.
   UTF-8 is the default encoding assumed by XML in the absence of an
   "encoding" attribute or a byte order mark (BOM); thus, the "encoding"
   attribute in the XML declaration is OPTIONAL if UTF-8 encoding is
   used.  SPPF clients and servers MUST accept a UTF-8 BOM if present,
   though emitting a UTF-8 BOM is NOT RECOMMENDED.






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   Example XML declarations:

   <?xml version="1.0" encoding="UTF-8" standalone="no"?>

9.  Security Considerations

   Many SPPF implementations manage data that is considered confidential
   and critical.  Furthermore, SPPF implementations can support
   provisioning activities for multiple Registrars and Registrants.  As
   a result, any SPPF implementation must address the requirements for
   confidentiality, authentication, and authorization.

9.1.  Confidentiality and Authentication

   With respect to confidentiality and authentication, the substrate
   protocol requirements section of this document contains security
   properties that the substrate protocol must provide, so that
   authenticated endpoints can exchange data confidentially and with
   integrity protection.  Refer to Section 4 of this document and
   [RFC7878] for the specific solutions to authentication and
   confidentiality.

9.2.  Authorization

   With respect to authorization, the SPPF server implementation must
   define and implement a set of authorization rules that precisely
   address (1) which Registrars will be authorized to create/modify/
   delete each SPPF object type for a given Registrant(s) and (2) which
   Registrars will be authorized to view/get each SPPF object type for a
   given Registrant(s).  These authorization rules are a matter of
   policy and are not specified within the context of SPPF.  However,
   any SPPF implementation must specify these authorization rules in
   order to function in a reliable and safe manner.

9.3.  Denial of Service

   In general, guidance on Denial-of-Service (DoS) issues is given in
   "Internet Denial of Service Considerations" [RFC4732], which also
   gives a general vocabulary for describing the DoS issue.

   SPPF is a high-level client-server protocol that can be implemented
   on lower-level mechanisms such as remote procedure call and web-
   service API protocols.  As such, it inherits any Denial-of-Service
   issues inherent to the specific lower-level mechanism used for any
   implementation of SPPF.  SPPF also has its own set of higher-level
   exposures that are likely to be independent of lower-layer mechanism
   choices.




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9.3.1.  DoS Issues Inherited from the Substrate Mechanism

   In general, an SPPF implementation is dependent on the selection and
   implementation of a lower-level substrate protocol and a binding
   between that protocol and SPPF.  The archetypal SPPF implementation
   uses XML [W3C.REC-xml-20081126] representation in a SOAP [SOAPREF]
   request/response framework over HTTP [RFC7230], probably also uses
   Transport Layer Security (TLS) [RFC5246] for on-the-wire data
   integrity and participant authentication, and might use HTTP Digest
   authentication [RFC2069].

   The typical deployment scenario for SPPF is to have servers in a
   managed facility; therefore, techniques such as Network Ingress
   Filtering [RFC2827] are generally applicable.  In short, any DoS
   mechanism affecting a typical HTTP implementation would affect such
   an SPPF implementation; therefore, the mitigation tools for HTTP in
   general also apply to SPPF.

   SPPF does not directly specify an authentication mechanism; instead,
   it relies on the lower-level substrate protocol to provide for
   authentication.  In general, authentication is an expensive
   operation, and one apparent attack vector is to flood an SPPF server
   with repeated requests for authentication, thereby exhausting its
   resources.  Therefore, SPPF implementations SHOULD be prepared to
   handle authentication floods, perhaps by noting repeated failed login
   requests from a given source address and blocking that source
   address.

9.3.2.  DoS Issues Specific to SPPF

   The primary defense mechanism against DoS within SPPF is
   authentication.  Implementations MUST tightly control access to the
   SPPF service, SHOULD implement DoS and other policy control
   screening, and MAY employ a variety of policy violation reporting and
   response measures such as automatic blocking of specific users and
   alerting of operations personnel.  In short, the primary SPPF
   response to DoS-like activity by a user is to block that user or
   subject their actions to additional review.

   SPPF allows a client to submit multiple-element or "batch" requests
   that may insert or otherwise affect a large amount of data with a
   single request.  In the simplest case, the server progresses
   sequentially through each element in a batch, completing one before
   starting the next.  Mid-batch failures are handled by stopping the
   batch and rolling back the data store to its pre-request state.  This
   "stop and roll back" design provides a DoS opportunity.  A hostile
   client could repeatedly issue large batch requests with one or more
   failing elements, causing the server to repeatedly stop and roll back



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   large transactions.  The suggested response is to monitor clients for
   such failures and take administrative action (such as blocking the
   user) when an excessive number of rollbacks is reported.

   An additional suggested response is for an implementer to set their
   maximum allowable XML message size and their maximum allowable batch
   size at a level that they feel protects their operational instance,
   given the hardware sizing they have in place and the expected load
   and size needs that their users expect.

9.4.  Information Disclosure

   It is not uncommon for the logging systems to document on-the-wire
   messages for various purposes, such as debugging, auditing, and
   tracking.  At the minimum, the various support and administration
   staff will have access to these logs.  Also, if an unprivileged user
   gains access to the SPPF deployments and/or support systems, it will
   have access to the information that is potentially deemed
   confidential.  To manage information disclosure concerns beyond the
   substrate level, SPPF implementations MAY provide support for
   encryption at the SPPF object level.

9.5.  Non-repudiation

   In some situations, it may be required to protect against denial of
   involvement (see [RFC4949]) and tackle non-repudiation concerns in
   regard to SPPF messages.  This type of protection is useful to
   satisfy authenticity concerns related to SPPF messages beyond the
   end-to-end connection integrity, confidentiality, and authentication
   protection that the substrate layer provides.  This is an optional
   feature, and some SPPF implementations MAY provide support for it.

9.6.  Replay Attacks

   Anti-replay protection ensures that a given SPPF object replayed at a
   later time won't affect the integrity of the system.  SPPF provides
   at least one mechanism to fight against replay attacks.  Use of the
   optional client transaction identifier allows the SPPF client to
   correlate the request message with the response and to be sure that
   it is not a replay of a server response from earlier exchanges.  Use
   of unique values for the client transaction identifier is highly
   encouraged to avoid chance matches to a potential replay message.









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9.7.  Compromised or Malicious Intermediary

   The SPPF client or Registrar can be a separate entity acting on
   behalf of the Registrant in facilitating provisioning transactions to
   the Registry.  Therefore, even though the substrate layer provides
   end-to-end protection for each specific SPPP connection between
   client and server, data might be available in clear text before or
   after it traverses an SPPP connection.  Therefore, a
   man-in-the-middle attack by one of the intermediaries is a
   possibility that could affect the integrity of the data that belongs
   to the Registrant and/or expose peering data to unintended actors.

10.  Internationalization Considerations

   Character encodings to be used for SPPF elements are described in
   Section 8.2.  The use of time elements in the protocol is specified
   in Section 3.2.  Where human-readable messages that are presented to
   an end user are used in the protocol, those messages SHOULD be tagged
   according to [RFC5646], and the substrate protocol MUST support a
   respective mechanism to transmit such tags together with those human-
   readable messages.

11.  IANA Considerations

11.1.  URN Assignments

   This document uses URNs to describe XML Namespaces and XML Schemas
   conforming to a Registry mechanism described in [RFC3688].

   Two URI assignments have been made:

   Registration for the SPPF XML Namespace:
   urn:ietf:params:xml:ns:sppf:base:1
   Registrant Contact: The IESG
   XML: None.  Namespace URIs do not represent an XML specification.

   Registration request for the XML Schema:

   URI: urn:ietf:params:xml:schema:sppf:1
   Registrant Contact: IESG
   XML: See "Formal Specification" (Section 12 of this document).










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11.2.  Organization Identifier Namespace Registry

   IANA has created and will maintain a registry titled "SPPF OrgIdType
   Namespaces".  The formal syntax is described in Section 5.1.

   Assignments consist of the OrgIdType Namespace string and the
   definition of the associated Namespace.  This document makes the
   following initial assignment for the OrgIdType Namespaces:

         OrgIdType Namespace string                       Namespace
         --------------------------                       ---------
         IANA Enterprise Numbers                          iana-en

   Future assignments are to be made through the well-known IANA Policy
   "RFC Required" (see Section 4.1 of [RFC5226]).  Such assignments will
   typically be requested when a new Namespace for identification of SPs
   is defined.

12.  Formal Specification

   This section provides the XSD for the SPPF protocol.

   <?xml version="1.0" encoding="UTF-8"?>
   <schema xmlns:sppfb="urn:ietf:params:xml:ns:sppf:base:1"
   xmlns="http://www.w3.org/2001/XMLSchema"
   targetNamespace="urn:ietf:params:xml:ns:sppf:base:1"
   elementFormDefault="qualified" xml:lang="EN">
    <annotation>
     <documentation>
      ---- Generic object key types to be defined by specific
           substrate/architecture.  The types defined here can
           be extended by the specific architecture to
           define the Object Identifiers. ----
     </documentation>
    </annotation>
    <complexType name="ObjKeyType"
     abstract="true">
     <annotation>
      <documentation>
       ---- Generic type that represents the
            key for various objects in SPPF. ----
      </documentation>
     </annotation>
    </complexType>







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    <complexType name="SedGrpOfferKeyType" abstract="true">
     <complexContent>
      <extension base="sppfb:ObjKeyType">
       <annotation>
        <documentation>
        ---- Generic type that represents
             the key for a SED Group Offer. ----
        </documentation>
       </annotation>
      </extension>
     </complexContent>
    </complexType>

    <complexType name="PubIdKeyType" abstract="true">
     <complexContent>
      <extension base="sppfb:ObjKeyType">
       <annotation>
        <documentation>
         ----Generic type that
         represents the key
         for a Pub ID. ----
        </documentation>
       </annotation>
      </extension>
     </complexContent>
    </complexType>

    <annotation>
     <documentation>
       ---- Object Type Definitions ----
     </documentation>
    </annotation>

    <complexType name="SedGrpType">
     <complexContent>
      <extension base="sppfb:BasicObjType">
       <sequence>
        <element name="sedGrpName" type="sppfb:ObjNameType"/>
        <element name="sedRecRef" type="sppfb:SedRecRefType"
                 minOccurs="0" maxOccurs="unbounded"/>
        <element name="dgName" type="sppfb:ObjNameType"
                 minOccurs="0" maxOccurs="unbounded"/>
        <element name="peeringOrg" type="sppfb:OrgIdType"
                 minOccurs="0" maxOccurs="unbounded"/>
        <element name="sourceIdent" type="sppfb:SourceIdentType"
                 minOccurs="0" maxOccurs="unbounded"/>
        <element name="isInSvc" type="boolean"/>
        <element name="priority" type="unsignedShort"/>



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        <element name="ext"
        type="sppfb:ExtAnyType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="DestGrpType">
     <complexContent>
      <extension base="sppfb:BasicObjType">
       <sequence>
        <element name="dgName"
        type="sppfb:ObjNameType"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="PubIdType" abstract="true">
     <complexContent>
      <extension base="sppfb:BasicObjType">
       <sequence>
        <element name="dgName" type="sppfb:ObjNameType"
                 minOccurs="0" maxOccurs="unbounded"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="TNType">
     <complexContent>
      <extension base="sppfb:PubIdType">
       <sequence>
        <element name="tn" type="sppfb:NumberValType"/>
        <element name="corInfo" type="sppfb:CORInfoType" minOccurs="0"/>
        <element name="sedRecRef" type="sppfb:SedRecRefType"
                 minOccurs="0" maxOccurs="unbounded"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="TNRType">
     <complexContent>
      <extension base="sppfb:PubIdType">
       <sequence>
        <element name="range" type="sppfb:NumberRangeType"/>
        <element name="corInfo" type="sppfb:CORInfoType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>



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    <complexType name="TNPType">
     <complexContent>
      <extension base="sppfb:PubIdType">
       <sequence>
        <element name="tnPrefix" type="sppfb:NumberValType"/>
        <element name="corInfo" type="sppfb:CORInfoType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="RNType">
     <complexContent>
      <extension base="sppfb:PubIdType">
       <sequence>
        <element name="rn" type="sppfb:NumberValType"/>
        <element name="corInfo" type="sppfb:CORInfoType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
     <complexType name="URIPubIdType">
     <complexContent>
      <extension base="sppfb:PubIdType">
       <sequence>
        <element name="uri" type="anyURI"/>
        <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="SedRecType" abstract="true">
     <complexContent>
      <extension base="sppfb:BasicObjType">
       <sequence>
        <element name="sedName" type="sppfb:ObjNameType"/>
        <element name="sedFunction" type="sppfb:SedFunctionType"
                 minOccurs="0"/>
        <element name="isInSvc" type="boolean"/>
        <element name="ttl" type="positiveInteger" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="NAPTRType">
     <complexContent>
      <extension base="sppfb:SedRecType">
       <sequence>
        <element name="order" type="unsignedShort"/>



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        <element name="flags" type="sppfb:FlagsType" minOccurs="0"/>
        <element name="svcs" type="sppfb:SvcType"/>
        <element name="regx" type="sppfb:RegexParamType" minOccurs="0"/>
        <element name="repl" type="sppfb:ReplType" minOccurs="0"/>
        <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="NSType">
     <complexContent>
      <extension base="sppfb:SedRecType">
       <sequence>
        <element name="hostName" type="token"/>
        <element name="ipAddr" type="sppfb:IPAddrType"
                 minOccurs="0" maxOccurs="unbounded"/>
        <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="URIType">
     <complexContent>
      <extension base="sppfb:SedRecType">
       <sequence>
        <element name="ere" type="token" default="^(.*)$"/>
        <element name="uri" type="anyURI"/>
        <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="SedGrpOfferType">
     <complexContent>
      <extension base="sppfb:BasicObjType">
       <sequence>
        <element name="sedGrpOfferKey" type="sppfb:SedGrpOfferKeyType"/>
        <element name="status" type="sppfb:SedGrpOfferStatusType"/>
        <element name="offerDateTime" type="dateTime"/>
        <element name="acceptDateTime" type="dateTime" minOccurs="0"/>
        <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <complexType name="EgrRteType">
     <complexContent>
      <extension base="sppfb:BasicObjType">



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       <sequence>
        <element name="egrRteName" type="sppfb:ObjNameType"/>
        <element name="pref" type="unsignedShort"/>
        <element name="regxRewriteRule" type="sppfb:RegexParamType"/>
        <element name="ingrSedGrp" type="sppfb:ObjKeyType"
                 minOccurs="0" maxOccurs="unbounded"/>
        <element name="svcs" type="sppfb:SvcType" minOccurs="0"/>
        <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
       </sequence>
      </extension>
     </complexContent>
    </complexType>
    <annotation>
     <documentation>
      ---- Abstract Object and Element Type Definitions ----
     </documentation>
    </annotation>
    <complexType name="BasicObjType" abstract="true">
     <sequence>
      <element name="rant" type="sppfb:OrgIdType"/>
      <element name="rar" type="sppfb:OrgIdType"/>
      <element name="cDate" type="dateTime" minOccurs="0"/>
      <element name="mDate" type="dateTime" minOccurs="0"/>
      <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
     </sequence>
    </complexType>
    <complexType name="RegexParamType">
     <sequence>
      <element name="ere" type="sppfb:RegexType" default="^(.*)$"/>
      <element name="repl" type="sppfb:ReplType"/>
     </sequence>
    </complexType>
    <complexType name="IPAddrType">
     <sequence>
      <element name="addr" type="sppfb:AddrStringType"/>
      <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
     </sequence>
     <attribute name="type" type="sppfb:IPType" default="v4"/>
    </complexType>
    <complexType name="SedRecRefType">
     <sequence>
      <element name="sedKey" type="sppfb:ObjKeyType"/>
      <element name="priority" type="unsignedShort"/>
      <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
     </sequence>
    </complexType>
    <complexType name="SourceIdentType">
     <sequence>



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      <element name="sourceIdentRegex" type="sppfb:RegexType"/>
      <element name="sourceIdentScheme"
               type="sppfb:SourceIdentSchemeType"/>
      <element name="ext" type="sppfb:ExtAnyType" minOccurs="0"/>
     </sequence>
    </complexType>
    <complexType name="CORInfoType">
     <sequence>
      <element name="corClaim" type="boolean" default="true"/>
      <element name="cor" type="boolean" default="false" minOccurs="0"/>
      <element name="corDate" type="dateTime" minOccurs="0"/>
     </sequence>
    </complexType>
    <complexType name="SvcMenuType">
     <sequence>
      <element name="serverStatus" type="sppfb:ServerStatusType"/>
      <element name="majMinVersion" type="token" maxOccurs="unbounded"/>
      <element name="objURI" type="anyURI" maxOccurs="unbounded"/>
      <element name="extURI" type="anyURI"
               minOccurs="0" maxOccurs="unbounded"/>
     </sequence>
    </complexType>
    <complexType name="ExtAnyType">
     <sequence>
      <any namespace="##other" maxOccurs="unbounded"/>
     </sequence>
    </complexType>
    <simpleType name="FlagsType">
     <restriction base="token">
      <length value="1"/>
      <pattern value="[A-Z]|[a-z]|[0-9]"/>
     </restriction>
    </simpleType>
    <simpleType name="SvcType">
     <restriction base="token">
      <minLength value="1"/>
     </restriction>
    </simpleType>
    <simpleType name="RegexType">
     <restriction base="token">
      <minLength value="1"/>
     </restriction>
    </simpleType>
    <simpleType name="ReplType">
     <restriction base="token">
      <minLength value="1"/>
      <maxLength value="255"/>
     </restriction>



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    </simpleType>
    <simpleType name="OrgIdType">
     <restriction base="token"/>
    </simpleType>
    <simpleType name="ObjNameType">
     <restriction base="token">
      <minLength value="3"/>
      <maxLength value="80"/>
     </restriction>
    </simpleType>
    <simpleType name="TransIdType">
     <restriction base="token">
      <minLength value="3"/>
      <maxLength value="120"/>
     </restriction>
    </simpleType>
    <simpleType name="MinorVerType">
     <restriction base="unsignedLong"/>
    </simpleType>
    <simpleType name="AddrStringType">
     <restriction base="token">
      <minLength value="3"/>
      <maxLength value="45"/>
     </restriction>
    </simpleType>
    <simpleType name="IPType">
     <restriction base="token">
      <enumeration value="v4"/>
      <enumeration value="v6"/>
     </restriction>
    </simpleType>
    <simpleType name="SourceIdentSchemeType">
     <restriction base="token">
      <enumeration value="uri"/>
      <enumeration value="ip"/>
      <enumeration value="rootDomain"/>
     </restriction>
    </simpleType>
    <simpleType name="ServerStatusType">
     <restriction base="token">
      <enumeration value="inService"/>
      <enumeration value="outOfService"/>
     </restriction>
    </simpleType>
    <simpleType name="SedGrpOfferStatusType">
     <restriction base="token">
      <enumeration value="offered"/>
      <enumeration value="accepted"/>



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     </restriction>
    </simpleType>
    <simpleType name="NumberValType">
     <restriction base="token">
      <maxLength value="20"/>
      <pattern value="\+?\d\d*"/>
     </restriction>
    </simpleType>
    <simpleType name="NumberTypeEnum">
     <restriction base="token">
      <enumeration value="TN"/>
      <enumeration value="TNPrefix"/>
      <enumeration value="RN"/>
     </restriction>
    </simpleType>
    <simpleType name="SedFunctionType">
     <restriction base="token">
      <enumeration value="routing"/>
      <enumeration value="lookup"/>
     </restriction>
    </simpleType>
    <complexType name="NumberType">
     <sequence>
      <element name="value" type="sppfb:NumberValType"/>
      <element name="type" type="sppfb:NumberTypeEnum"/>
     </sequence>
    </complexType>
    <complexType name="NumberRangeType">
     <sequence>
      <element name="startRange" type="sppfb:NumberValType"/>
      <element name="endRange" type="sppfb:NumberValType"/>
     </sequence>
    </complexType>
   </schema>

















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13.  References

13.1.  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,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2277]  Alvestrand, H., "IETF Policy on Character Sets and
              Languages", BCP 18, RFC 2277, DOI 10.17487/RFC2277,
              January 1998, <http://www.rfc-editor.org/info/rfc2277>.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <http://www.rfc-editor.org/info/rfc3629>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <http://www.rfc-editor.org/info/rfc3688>.

   [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,
              <http://www.rfc-editor.org/info/rfc3986>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <http://www.rfc-editor.org/info/rfc5234>.

   [RFC7878]  Cartwright, K., Bhatia, V., Mule, J., and A. Mayrhofer,
              "Session Peering Provisioning (SPP) Protocol over SOAP",
              RFC 7878, DOI 10.17487/RFC7878, August 2016,
              <http://www.rfc-editor.org/info/rfc7878>.

   [W3C.REC-xml-20081126]
              Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and
              F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
              Edition)", World Wide Web Consortium Recommendation REC-
              xml-20081126, November 2008,
              <http://www.w3.org/TR/2008/REC-xml-20081126>.




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13.2.  Informative References

   [RFC2069]  Franks, J., Hallam-Baker, P., Hostetler, J., Leach, P.,
              Luotonen, A., Sink, E., and L. Stewart, "An Extension to
              HTTP : Digest Access Authentication", RFC 2069,
              DOI 10.17487/RFC2069, January 1997,
              <http://www.rfc-editor.org/info/rfc2069>.

   [RFC2781]  Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO
              10646", RFC 2781, DOI 10.17487/RFC2781, February 2000,
              <http://www.rfc-editor.org/info/rfc2781>.

   [RFC2827]  Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source
              Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
              May 2000, <http://www.rfc-editor.org/info/rfc2827>.

   [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,
              <http://www.rfc-editor.org/info/rfc3261>.

   [RFC3403]  Mealling, M., "Dynamic Delegation Discovery System (DDDS)
              Part Three: The Domain Name System (DNS) Database",
              RFC 3403, DOI 10.17487/RFC3403, October 2002,
              <http://www.rfc-editor.org/info/rfc3403>.

   [RFC4725]  Mayrhofer, A. and B. Hoeneisen, "ENUM Validation
              Architecture", RFC 4725, DOI 10.17487/RFC4725, November
              2006, <http://www.rfc-editor.org/info/rfc4725>.

   [RFC4732]  Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet
              Denial-of-Service Considerations", RFC 4732,
              DOI 10.17487/RFC4732, December 2006,
              <http://www.rfc-editor.org/info/rfc4732>.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
              <http://www.rfc-editor.org/info/rfc4949>.

   [RFC5067]  Lind, S. and P. Pfautz, "Infrastructure ENUM
              Requirements", RFC 5067, DOI 10.17487/RFC5067, November
              2007, <http://www.rfc-editor.org/info/rfc5067>.







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   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <http://www.rfc-editor.org/info/rfc5246>.

   [RFC5486]  Malas, D., Ed. and D. Meyer, Ed., "Session Peering for
              Multimedia Interconnect (SPEERMINT) Terminology",
              RFC 5486, DOI 10.17487/RFC5486, March 2009,
              <http://www.rfc-editor.org/info/rfc5486>.

   [RFC5646]  Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
              Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
              September 2009, <http://www.rfc-editor.org/info/rfc5646>.

   [RFC6116]  Bradner, S., Conroy, L., and K. Fujiwara, "The E.164 to
              Uniform Resource Identifiers (URI) Dynamic Delegation
              Discovery System (DDDS) Application (ENUM)", RFC 6116,
              DOI 10.17487/RFC6116, March 2011,
              <http://www.rfc-editor.org/info/rfc6116>.

   [RFC6461]  Channabasappa, S., Ed., "Data for Reachability of Inter-
              /Intra-NetworK SIP (DRINKS) Use Cases and Protocol
              Requirements", RFC 6461, DOI 10.17487/RFC6461, January
              2012, <http://www.rfc-editor.org/info/rfc6461>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,
              <http://www.rfc-editor.org/info/rfc7230>.

   [SOAPREF]  Gudgin, M., Hadley, M., Moreau, J., and H. Nielsen, "SOAP
              Version 1.2 Part 1: Messaging Framework", W3C REC REC-
              SOAP12-part1-20030624, June 2003,
              <http://www.w3.org/TR/soap12-part1/>.

   [Unicode6.1]
              The Unicode Consortium, "The Unicode Standard, Version
              6.1.0", (Mountain View, CA: The Unicode Consortium,
              2012. ISBN 978-1-936213-02-3),
              <http://unicode.org/versions/Unicode6.1.0/>.











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Acknowledgements

   This document is a result of various discussions held in the DRINKS
   working group and within the DRINKS protocol design team, with
   contributions from the following individuals, in alphabetical order:
   Syed Ali, Jeremy Barkan, Vikas Bhatia, Sumanth Channabasappa, Lisa
   Dusseault, Deborah A.  Guyton, Otmar Lendl, Manjul Maharishi, Mickael
   Marrache, Alexander Mayrhofer, Samuel Melloul, David Schwartz, and
   Richard Shockey.

Authors' Addresses

   Kenneth Cartwright
   TNS
   1939 Roland Clarke Place
   Reston, VA  20191
   United States

   Email: kcartwright@tnsi.com


   Vikas Bhatia
   TNS
   1939 Roland Clarke Place
   Reston, VA  20191
   United States

   Email: vbhatia@tnsi.com


   Syed Wasim Ali
   NeuStar
   46000 Center Oak Plaza
   Sterling, VA  20166
   United States

   Email: syed.ali@neustar.biz


   David Schwartz
   XConnect
   316 Regents Park Road
   London  N3 2XJ
   United Kingdom

   Email: dschwartz@xconnect.net





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