Internet DRAFT - draft-ietf-modern-teri
draft-ietf-modern-teri
Network Working Group J. Peterson
Internet-Draft Neustar, Inc.
Intended status: Standards Track June 29, 2018
Expires: December 31, 2018
An Architecture and Information Model for Telephone-Related Information
(TeRI)
draft-ietf-modern-teri-00
Abstract
As telephone services migrate to the Internet, Internet applications
require tools to access and manage information about telephone
numbers. This document specifies a protocol-independent framework
and information model for managing service and administration data
related to telephone numbers.
Status of This Memo
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Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. The Information Model . . . . . . . . . . . . . . . . . . . . 5
3.1. Record Elements . . . . . . . . . . . . . . . . . . . . . 6
3.1.1. Identifier . . . . . . . . . . . . . . . . . . . . . 6
3.1.2. Authority . . . . . . . . . . . . . . . . . . . . . . 6
3.1.3. Access . . . . . . . . . . . . . . . . . . . . . . . 6
3.1.4. Subject . . . . . . . . . . . . . . . . . . . . . . . 6
3.1.5. Signature . . . . . . . . . . . . . . . . . . . . . . 6
3.1.6. Administrative Elements . . . . . . . . . . . . . . . 7
3.1.6.1. Contact . . . . . . . . . . . . . . . . . . . . . 7
3.1.7. Service Elements . . . . . . . . . . . . . . . . . . 7
3.1.7.1. Service . . . . . . . . . . . . . . . . . . . . . 7
3.1.7.1.1. Priority . . . . . . . . . . . . . . . . . . 7
3.1.7.1.2. Expiration . . . . . . . . . . . . . . . . . 7
3.2. Element Value Types . . . . . . . . . . . . . . . . . . . 8
3.2.1. Service Types . . . . . . . . . . . . . . . . . . . . 8
3.2.1.1. Telephone Number Type . . . . . . . . . . . . . . 8
3.2.1.1.1. TN Range Type . . . . . . . . . . . . . . . . 8
3.2.1.2. Domain Name Type . . . . . . . . . . . . . . . . 8
3.2.1.3. Uniform Resource Indicator (URI) Type . . . . . . 8
3.2.1.4. Internet Protocol (IP) Address Type . . . . . . . 9
3.2.1.5. Trunk Group Type . . . . . . . . . . . . . . . . 9
3.2.1.6. Service Provider Identifier (SPID) Type . . . . . 9
3.2.2. Public Key Type . . . . . . . . . . . . . . . . . . . 9
3.2.3. Contact Type . . . . . . . . . . . . . . . . . . . . 9
3.2.4. Access Type . . . . . . . . . . . . . . . . . . . . . 9
3.2.5. Expiry Type . . . . . . . . . . . . . . . . . . . . . 10
3.2.6. Priority Type . . . . . . . . . . . . . . . . . . . . 10
3.2.7. Record Identifier Type . . . . . . . . . . . . . . . 10
3.2.8. Signature . . . . . . . . . . . . . . . . . . . . . . 10
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3.2.9. Extension Type . . . . . . . . . . . . . . . . . . . 10
4. Relationship to the MODERN Framework . . . . . . . . . . . . 10
5. TeRI Client-Server Operations . . . . . . . . . . . . . . . . 12
5.1. Elements Common to All Operations . . . . . . . . . . . . 13
5.1.1. Requests . . . . . . . . . . . . . . . . . . . . . . 13
5.1.1.1. Source . . . . . . . . . . . . . . . . . . . . . 14
5.1.1.1.1. Request Source . . . . . . . . . . . . . . . 14
5.1.1.1.2. Request Intermediary . . . . . . . . . . . . 14
5.1.1.2. Subject . . . . . . . . . . . . . . . . . . . . . 15
5.1.1.2.1. Request Restrictions . . . . . . . . . . . . 15
5.1.2. Responses . . . . . . . . . . . . . . . . . . . . . . 15
5.1.2.1. Response Code . . . . . . . . . . . . . . . . . . 15
5.2. The Acquisition Operation . . . . . . . . . . . . . . . . 15
5.3. The Management Operation . . . . . . . . . . . . . . . . 16
5.3.1. Service-to-Service Record Distribution . . . . . . . 17
5.4. The Retrieval Operation . . . . . . . . . . . . . . . . . 17
5.5. Common Restrictions . . . . . . . . . . . . . . . . . . . 17
5.5.1. Route Source . . . . . . . . . . . . . . . . . . . . 18
5.6. Implementing Operations . . . . . . . . . . . . . . . . . 18
5.6.1. Transport Independence . . . . . . . . . . . . . . . 18
5.6.2. Bindings . . . . . . . . . . . . . . . . . . . . . . 19
5.6.3. Encodings . . . . . . . . . . . . . . . . . . . . . . 20
5.6.4. Profiles and Extension Elements . . . . . . . . . . . 21
6. Security Considerations . . . . . . . . . . . . . . . . . . . 21
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22
9. Informative References . . . . . . . . . . . . . . . . . . . 22
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 24
1. Terminology
In this document, the key words "MAY", "MUST, "MUST NOT", "SHOULD",
and "SHOULD NOT", are to be interpreted as described in [RFC2119].
This document also incorporates the terminology of the MODERN
Framework [I-D.ietf-modern-problem-framework].
2. Motivation
Telephone numbers remain the worldwide standard identifier for
routing calls and text messages over the Public Switched Telephone
Network (PSTN). Increasingly, real-time communications is migrating
to the Internet, and bringing telephone numbers with it. As
identifiers, however, telephone numbers differ fundamentally from
those commonly used by Internet applications. Email, the web and
native Voice over IP (VoIP) systems such as SIP ([RFC3261]) use
identifiers that rely on the Domain Name System (DNS) to resolve a
domain portion of the identifier to a particular IP address;
commonly, Uniform Resource Indicators (URIs) with a user and host
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component serve this purpose. SIP, for example, quickly developed a
convention for using a TEL URI in the user part of its URIs. To help
telephone numbers work similarly on the Internet, a number of efforts
have specified mechanisms to manage and retrieve information about
telephone numbers via network services.
The ENUM ([RFC6116]) effort originally specified a public DNS profile
for translating telephone numbers into URIs. Due to the difficulty
of coordinating the public administration of telephone numbers in the
DNS, this work transitioned to "infrastructure" ENUM ([RFC5067]),
which assumed private DNS implementations, each of which could give a
different answer to the same request to translate a telephone number
depending on who asked, or other internal factors. The framework of
the SPEERMINT working group ([RFC6406]), expanding on these
requirements, differentiated the mapping of a telephone number to a
target network (the "Look-up Function") from the mapping made by the
originating network to the proper next-hop to reach such a target
network (the "Location Routing Function"). To provision the data
associated with telephone numbers, the DRINKS working group
([RFC6461]) designed systems for uploading back-end data to the
services that would answer ENUM queries.
None of the preceding efforts, however, encompassed the entire
lifecycle of a telephone number as an Internet identifier. They
focused largely on service data, on how to "resolve" a telephone
number to a location on the Internet, rather than on administrative
questions of how numbers are acquired, how the entities associated
with telephone numbers are authorized to provision data, and what
kinds of systems need to be in place to allow a diverse community of
devices, applications and users to rely on telephone numbers. Early
considerations were moreover based on overlapping, but not entirely
consistent, information models: intrinsic limitations in the DNS kept
the queries and responses of ENUM relatively simple, whereas the
DRINKS provisioning system considered a much richer syntax.
The need for solutions in this space is pressing, as many carriers
worldwide contemplate migrating their entire PSTN infrastructure onto
the Internet within the next decade. Further pressures come from
emerging Internet communications providers who never invested in PSTN
infrastructure in the first place, but want access to services
related to telephone numbers. This includes devices, services, and
applications on the Internet that make use of telephone numbers and
need to distribute and manage numbering inventory: for example, an
Internet-enabled PBX that might want to automate the process for
allowing new connected phones to acquire numbers and provision
contact information for their users. Ultimately, the resources
identified by telephone numbers must also be reachable on the
Internet, and different applications might want to use different
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protocols to retrieve information about numbers. In some
environments, there are performance constraints that would require a
very lightweight binary protocol; in others, applications might
prefer human-readable markup languages suitable for interfacing with
existing APIs. The use cases associated with these functions are
detailed in [I-D.ietf-modern-problem-framework].
Therefore, this document proposes a reconsideration of telephone
service and administration data on the Internet, based on an
information model that allows records associated with telephone
number to be created, modified and accessed through network
interfaces. This document specifies no particular syntax or encoding
for queries or responses, but instead describes an extensible
information model for the semantics of provisioning and querying
operations associated with a telephone number.
3. The Information Model
The fundamental building block of the TeRI model is the Record. A
Record is created by an Authority who has authority over a particular
telephone number or a set of numbers. There may be more than one
Authority who is authorized to create Records for a particular
telephone number, and a TeRI service may have multiple Records
corresponding to a single telephone number, including potentially
overlapping Records associated with a range of numbers that
encompasses a particular telephone number. Under various
circumstances detailed in Section 5, participants in the numbering
ecosystem may create, read, update, and modify Records.
Records contain Elements that hold data about the telephone number.
Elements in this information model have a Name, which may optionally
be associated with a Type and Value. Records are divided into two
broad categories: Administrative Records and Service Records.
Administrative Records hold data about how records have been
allocated that is typically generated by a Registrar or similar
entity that distributes numbers; they include information on the
administrative contacts for telephone numbers, and so on. Service
Records hold data required to initiate communication with the
resources reachable at a telephone number; these Records are
typically generated by an assignee or delegate such as a CSP.
The distinction between Administrative and Service Records exists
because different parties might only need acces to one sort of
information instead of another: moreover, some actors may be
authorized to view Service Records for a particular telephone number
but not Administrative Records, or vice versa. In practice, a Record
may contain both Administrative and Service Elements, but the
creators of Records may find it useful to keep the two types of
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information separate. If a Record contains both Administrative and
Service Elements, it may be returned in a Retrieval Query for either,
provided the Client is authorized to receive the Elements within.
3.1. Record Elements
A Record is made up of Elements, which may contain Service or
Administrative Data. All Records can contain the following generic
Elements.
3.1.1. Identifier
Every Record has an Identifier, which is a globally unique identifier
of the Record. The Identifier will typically be created at the same
time as the Record itself, at a time when an assignment or delegation
has occurred (as described in [I-D.ietf-modern-problem-framework]).
3.1.2. Authority
Every Record contains an Authority Element indicating the source of
the data: either the entity that provisioned the data with the
Service, or the external source from which the Service collected the
data. The Authority element ideally gives a logical identity of the
source of the data. A public key value may also be associated with
an Authority element.
3.1.3. Access
Every Record contains an Access Element indicating the conditions
under which Retrieval Requests can acquire the Record. The Access
Element is set by the Authority generating the Record.
3.1.4. Subject
Every Record has a Subject. As TeRI Records concern telephone
numbers, the Subject of a Record is an array of either a telephone
number type or a telephone number range type. The simplest Record
Subject is an array with one element consisting of a single telephone
number.
3.1.5. Signature
Optionally, a Record contains a Signature element. The Signature
element contains a signature over the concatenation of the other
elements given the Record. Signatures are provided by the Authority
responsible for the Record.
[Syntax TBD]
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3.1.6. Administrative Elements
Records that contain Administrative Elements are Administrative
Records. The baseline TeRI specification sets only one
Administrative Element, the Contact.
3.1.6.1. Contact
Every Administrative Record has at least one Contact. The Contact
contains administrative data about the assignee of the telephone
number, though additionally Contacts may contain information about
delegates (as defined in [I-D.ietf-modern-problem-framework]).
Typically, this information would be set by the Registrar; policies
outside the scope of this specification dictate the sorts of entities
that may be designated as Contacts in Records.
3.1.7. Service Elements
Records that contain a Service Element are Service Records. The most
important Service Element is simply called Service, and it contains
an identifier for a communications resource reachable through a
telephone number. More than one Service Element can appear in a
given Record. Other Service Elements may be defined by later
specifications.
3.1.7.1. Service
Records optionally have one or more Service entries. A Service may
be of any Service Type, as given in Section 3.2.1. Optionally,
subelements modify how a Service Element should be retained.
3.1.7.1.1. Priority
Optionally, a Service may specify a weighted Priority associated with
a Record. Priorities are between 0 and 1, with a value of 1 having
the highest priority.
3.1.7.1.2. Expiration
Optionally, a Service may specify an absolute time at which a Record
will no longer be valid, should a client or intermediary wish to
cache a Record. In the absence of an Expiration element, Records may
be cached for a maximum of twenty-four hours.
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3.2. Element Value Types
The remainder of a Record is made up of Elements. Elements types are
specified in this section. Every Element Type has a Type Code. A
Type Code is used as a short form for the Element in a Record.
3.2.1. Service Types
3.2.1.1. Telephone Number Type
The telephone number type conforms to the telephone number syntax
given in [RFC3966] Section 3, in the ABNF for "telephone-subscriber."
Type Code: T
[TBD - need for subtying? E.164, Service Code, Short Code, Prefix,
Nationally-Specific and Unknown. ]
3.2.1.1.1. TN Range Type
The TN range type consists of a prefix of a telephone number (per
[RFC3966] "telephone-subscriber"), and is semantically equivalent to
all syntactically-valid telephone numbers below that prefix. For
example, in the North American Numbering plan, the prefix 157143454
would be equivalent to all numbers ranging from 15714345400 to
15714345499.
[TBD - identify alternative ways of specifying ranges, potentially as
separate element types]
Type Code: R
3.2.1.2. Domain Name Type
The domain name type conforms to the syntax of RFC1034 Section 3.5
and Section 2.1 of [RFC1123].
Type Code: D
3.2.1.3. Uniform Resource Indicator (URI) Type
The Uniform Resource Indicator (URI) type conforms to the syntax for
URIs given in [RFC3986] (see Section 3).
Type Code: U
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3.2.1.4. Internet Protocol (IP) Address Type
The IP Address type conforms to the ABNF syntax of either the
IPv4address given in RFC3986 (Appendix A) or the IPv6reference of
[RFC5954].
Type Code: I
3.2.1.5. Trunk Group Type
The trunk group type conforms to the "trunk-group-label" ABNF given
in [RFC4904] (Section 5).
Type Code: G
3.2.1.6. Service Provider Identifier (SPID) Type
The SPID type consists of a four-digit number.
[TBD - introduce other elements for alternative SPID syntaxes]
Type Code: ?
3.2.2. Public Key Type
The Credential type consists of a public key [encoding TBD].
Type Code: C
3.2.3. Contact Type
The contact type follows the conventions of jCard [RFC7095].
Type Code: C
3.2.4. Access Type
The access type consists of a string, which is set to the values
"Public," "Semi-restricted" or "Restricted." If either "Semi-
restricted" or "Restricted" appears as the access type, the Element
will need to be accompanied by a Permissions Element. [TBD - work to
be done here]
Type Code: A
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3.2.5. Expiry Type
The Expiry type is an absolute time conformant to the syntax of
[RFC3339].
Type Code: E
3.2.6. Priority Type
The Priority type contains a number between 0 and 1, conforming to
the specification of the "q" parameter of the Contact header field in
[RFC3261].
Type Code: P
3.2.7. Record Identifier Type
The Record Identifier Type consists of a unique identifier for a
record [format TBD].
Type Code: U
3.2.8. Signature
[Syntax TBD]
Type Code: S
3.2.9. Extension Type
This code is reserved for future use.
Type Code: X
4. Relationship to the MODERN Framework
The MODERN Framework [I-D.ietf-modern-problem-framework] enumerates a
series of actors and use cases related to telephone number
administration on the Internet. In terms of actors, it details
interactions between Users, Communications Service Providers (CSPs),
Registries, Registrars, and Government Entities. These actors
acquire, manage, or retrieve telephone numbers, implementing various
interfaces in support of different use cases. Registries in MODERN
may be centralized or decentralized. The TeRI Operations discussed
in this document pertain largely to centralized Registries: the
creation and propagation of Records for decentralized Registries is
outside the scope of this document. For centralized Registries,
client-server operations are conducted to acquire, manage, and
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retrieve telephone numbers with TeRI. Typically, Users, CSPs, and
Government Entities act as TeRI Clients, and CSPs, Registries, and
Registrars act as TeRI Services.
In the MODERN framework, the lifecycle of a number begins with a
Registry. Registrars acquire telephone numbers from Registries, and
make those numbers available for allocation. Thus, an Acquisition
Operation is used by a Registrar that acquires numbers from a
Registry, and this Request, if successful, will result in the
creation of a Record that is returned in the Response. That Record
renders the Registrar an Authority for the telephone numbers in
question, but that Record will contain exclusively Administrative
Data, with no Service Data.
In some cases, that Registrar will also fulfil the role of a CSP, and
as a CSP, it will allocate those numbers to Users and generate any
associated Records itself. Alternatively, a Registrar that does not
act as a CSP may in turn act as a TeRI Service to which CSPs, and
potentially Users, will send Acquisition Requests to acquire number
blocks or individual numbers. Through that process, CSPs and Users
can also become Authorities for telephone numbers. New Records
containing Administrative Data indicating the contact information and
so forth of the CSP or the User will be generated when that
allocation occurs; those Records will be stored at the Registrar.
The Registrar may also house a "glue" Record of Service Data that
indicates the servicing CSP for the telephone number, and in
particular the Retrieval interface of that CSP where Records with
further Service Data can be found.
The Authorities who create and propagate Records of Service Data are
typically CSPs and Users. Most commonly, CSPs will store these
Service Data Records, and make them accessible through a Retrieval
interface. CSPs may also propagate these Records to various external
directories; the signature of the CSP and expiry data in the Record
will prove its integrity and freshness to any relying party. It is
envisioned that multiple Authorities may create Records for different
services that are associated with a given telephone number.
Finally, CSPs and Users may query a Retrieval interface at a CSP to
acquire Records containing Service Data that will enable them to
route communications. The Retrieval interface will enable Clients to
ask for Records associated with particular services, though Retrieval
can present Clients with a number of service options. Entities may
also query the Retrieval Interface of Registrars to acquire
Administrative Data about a telephone number, though it is likely
that authorization policies will restrict access to that data.
Government Entities may have legal relationships with Registrars that
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grant them authorization privileges with regard to Administrative
Data.
5. TeRI Client-Server Operations
In TeRI, Clients use Operations to acquire, manage, or retrieve
Records, which are typically stored at Services. Every Operation
consists of a Request and a Response. Requests may pass directly
from a Client to a Service, or they may pass through one or more
Request Intermediaries; Request Intermediaries can modify Requests
and Responses in transit. A Response will contain a Response Code
indicating the status of the requested Operation. Both Requests and
Responses can, in certain Operations, carry Records. TeRI does not
specify any specific data format or underlying protocol to
instantiate Requests, Responses, or Records: TeRI is an abstract
architecture that must be implemented with concrete bindings and
encodings (see Section 5.6).
The TeRI information model (see Section 3) specifies the baseline
contents of Records, though Records are designed to be extended by
future specifications for particular use cases or environments.
Records provide information related to telephone numbers; a Record
may apply to one telephone number, a block of numbers, or several
discrete blocks of numbers. There may be multiple Records stored at
a Service which cover a single telephone number: this may include
multiple Records that apply only to that one telephone number, which
probably have been provisioned by different Authorities, as well as
Records applying to a telephone number range which contains that one
telephone number. Authorities sign Records, and Clients typically
have a trust relationship with those Authorities.
The three TeRI Operations are as follows:
The Acquisition Operation enables a Client to request the
allocation of unallocated telephone numbers that are held by a
Service on behalf of an Authority. A Service makes an
authorization decision before allocating the telephone number(s)
in accordance with the policy of the Authority. One or more new
Records may be created as a result of a successful Acquisition
Operation, and the Service will pass any such Record(s) to the
acquiring Client as well as retaining them locally at the Service.
As a result of a successful Acquisition Operation, the
administrative entity operating the Client will typically become a
new Authority for the allocated telephone numbers.
The Management Operation enables a Client to push new values for a
Record to a Service. In the baseline Operation described in this
document, the Client pushes the entire value of the Record to the
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Service. The Service then makes an authorization decision to
determine whether or not the Client is permitted to upload the
Record in question. The policy behind those authorization
decisions is outside the scope of this document, though at a high-
level, the Client must be an Authority for a telephone number in
order to publish and modify Records associated with that number.
However, outside of hierarchical Authorities, Clients will not be
able to modify or delete Records related to that number that have
been provisioned by other Authorities.
The Retrieval Operation enables a Client to request one or more
Records that are stored at a Service. Some Records may contain
public information, and some may contain information that requires
an authorization decision to be made before it is shared with a
Client. Note that Services may have trust relationships with
Request Intermediaries, and that the Response may depend on that
trust relationship rather than on the Service's trust relationship
with the Client. Although a Client acquires Records from a
Service, a Client need not have a trust relationship with it -
typically, the Client trusts the Record because it trusts the
Authority which signed the Record rather than the Service that
holds or delivers the Record.
All entities that act as TeRI Services will offer at least the
Management and Retrieval interfaces, and some will also offer the
Acquisition interface. All entities that act as TeRI Clients will
implement at least the Retrieval Operation; others may implement the
client side of one or both of the Management and Acquisition
Interfaces.
5.1. Elements Common to All Operations
All Operations in the TeRI model consist of Requests and Responses.
A Request from a TeRI Client to a Service may attempt to create,
read, update, or delete TeRI Records. Requests may use Restrictions
to focus only on particular parts of a TeRI Record. A Response gives
the result of the Operation back to the Client, which may indicate
success of failure.
5.1.1. Requests
All TeRI Requests have a Source, a Subject, and optionally a set of
Restrictions which further specify the nature of the Request. Some
Requests will contain the Identifier of the Record they concern;
others will query for all Records matching a given Subject.
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5.1.1.1. Source
The Source is a required element in all Requests. In this
specification, two categories of Sources are defined: Request Source
and Request Intermediary. At least one of these Sources must be
present in a Retrieval Request, and multiple Sources are permitted.
Responses do not contain a Source.
Future specifications may extend the set of Source types.
5.1.1.1.1. Request Source
Every Request generated by a Client has a Request Source, which
identifies the originator of the Request. This represents the
logical identity of the user or service provider who first sent the
Request, rather than the identity of any Intermediate entity. This
field is provided in the Source to authenticate the poser of the
Request, so that the Service can make any necessary authorization
decisions as it formulates a Response.
In some service deployments, an Intermediary may wish to mask the
Request's Source from a Service. The removal of the Request's Source
by an Intermediary is permitted by TeRI, but any Intermediary that
removes the Request Source must provide a Request Intermediary for
the Source element.
A Request Source element has a Type, which indicates how the logical
identity of the originator of the Request has been represented. The
Type field of the Request Source is extensible. Initial values
include a domain name, a URI and a telephone number.
The Type element of the Request Source is followed by a Value, which
contains the identity. The format of the identity is determined by
the Type.
5.1.1.1.2. Request Intermediary
Optionally, Requests may contain one or more Request Intermediary
elements in the Source. A Request Intermediary resides between the
originator of the Request (the Client) and the Service, where it may
aggregate queries, proxy them, transcode them, or provide any related
relay function to assist the delivery of Requests to the Service.
The Request Intermediary element, like the Request Source, contains
the logical identity of the service that relayed the Request. This
field is provided in the Source for those deployments in which the
Service makes an authorization decision based on the identity of the
Intermediary rather than a Request Source.
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A Request Intermediary element has a Type, which indicates how the
logical identity of the Intermediary has been represented. The Type
element of the Request Intermediary is extensible. Initial values
include a domain name, an X.509 certificate subject, or a URI.
The Type of the Request Intermediary element is followed by a Value,
which contains the identity. The format of the identity is
determined by the Type.
5.1.1.2. Subject
All Requests have a Subject. The Subject identifies the resource
that the Request concerns. Responses only contain a Subject if the
Subject of the Response differs from that of the original Request,
which may occur when (for example) the Subject contains a broad
range, and the Service replies with a more narrow Subject. Future
specifications, including Profiles, may define alternative Subject
elements.
5.1.1.2.1. Request Restrictions
TeRI Request Restrictions consist of a Name with an optional Type and
an Optional Value. Most Restrictions are specific to the Operation.
5.1.2. Responses
All TeRI Responses will have a Responde Code, and may contain one or
more Records.
5.1.2.1. Response Code
All Responses contain a Response Code.
Response Codes defined by this document include: Success, Subject
Does Not Exist, Subject Conflict, No Suitable Records Exist for
Subject, Subject Syntax Error, No Suitable Records Exist for
Restriction, Unauthorized Source, Route Source Topology Unavailable.
[TBD]
5.2. The Acquisition Operation
An Acquisition Request has a Source and a Subject, and may have one
or more Restrictions. An Acquisition Response has a Response Code,
and will contain one Record if it is successful.
The Subject of an Acquisition Request always specifies a Telephone
Number Type or a Telephone Number Range Type. If the Subject
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contains a particular telephone number, then the Acquisition Request
is a Request to acquire that particular telephone number. If it is a
range, the Acquisition Request should be considered to be for the
entire range, but future Restrictions defined for this the Request
might limit the scope of the resources requested. The Service will
determine whether or not the Client is authorized to acquire the
resources in question based on the Source of the Acquisition Request.
The Response to an Acquisition Request will contain a Success
Response Code if the resource can be allocated. The Subject of a
Success Response will always contain the Telephone Number Type or
Telephone Number Range that has been allocated. A successful
Acquisition Response must contain a Record with a Identifier Element;
that Record may also contain an Element containing tokens or other
material that the Client might use to acquire credentials from a
Credential Authority (see [I-D.ietf-modern-problem-framework]). By
default, this Record will contain only Administrative Elements,
without Service Elements. If a requested telephone number (or range)
is already allocated, or a telephone number in the specified range is
not available, then a Subject Conflict Response Code is returned.
5.3. The Management Operation
A Management Request comprises a Source, a Subject, and one or more
Records; it also may contain one or more Restrictions. A Management
Response contains a Response Code, and optionally may contain a
Record.
The Subject of a Management Request always specifies a Telephone
Number Type or a Telephone Number Range Type. In almost all
circumstances, however, the Service will locate that Record(s) that a
Management Request modifies through the Identifier Restriction on
each Record in the Management Request.
A Management Request contains at least one Record; it may contain
multiple Records. Each Record in the Management Request must contain
a Record Identifier Element which designates the Record that the
Client is requesting that the Service provision as or replace with
the Record included in the Management Request. The Service will
authorize whether or not the Client is authorized to modify the
Record in question via the Source of the Management Request.
The Management Operation not only provisions Records at a Service,
but also provisions at the Service any information needed by the
Service to make authorization and policy decisions when responding to
Retrieval Requests. This information is tied to the Access Element
of the Record.
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5.3.1. Service-to-Service Record Distribution
TeRI Records contain the signature of the Authority who generated
them, and as such, a relying party trusts a Record based on that
signature rather than based on the Service from which a Record was
retrieved. This permits architectures that allow a Records to be
duplicated across a distributed Service. Distribution protocols are
left to future specifications.
5.4. The Retrieval Operation
Every Retrieval Request comprises a Source and a Subject, and may
have one or more Restrictions. A Retrieval Response has a Response
Code, optionally one or more Records, and optionally a Subject, if
the Subject differs from that of the Request.
Retrieval Requests optionally contain Restrictions; a Request with no
specified Restrictions requests that the Service return any Records
associated with the Subject. In a Request, the presence of one or
more Restrictions limits the scope of the Request to Records about
the Subject containing those Elements, or the Restrictions otherwise
qualify the Request. Typically a Restriction will specify a Service
or Service Type that the Client seeks Records for.
Successful Retrieval Responses always contain one or more Records;
unsuccessful Responses never contain Records.
5.5. Common Restrictions
Restrictions are broadly structured around Elements, typically the
Service, Contact, and Identifier Elements. A TeRI Request may
contain a Restriction based on any Element, be it a baseline Element
or a Service or Administrative Element, including Elements that are
defined in future specifications. Semantically, a Restriction may
target Records that contain a particular Element, or only Elements
with a particular subtype or even value. Multiple Restrictions may
appear in a Request, and Restrictions are always additive, which is
to say that Restriction always narrow then target of a Request.
Restrictions may either name a target Element, or both an Element and
a value. For example, a Management Request replacing an existing
Record must name as its target with a Restriction both the Identifier
Element and the value, which is the identifier for the Record. A
Retrieval Request for a particular Subject might restrict itself to
Service elements, or even Service elements that have a particular
subtype, such as a URI.
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5.5.1. Route Source
Optionally, Retrieval Requests may contain a Route Source which
functions in much the same way as a Restriction. A Route Source
identifies a reference point in the network from which any Service
Elements in the response should be calculated. It therefore always
designates a network element, though depending on the circumstances,
it may be an endpoint, a gateway, a border device, or any other agent
that makes forwarding decisions for telephone calls and related
services. A Route Source is a subelement of the Source element.
A Route Source element has a Type, which indicates how the network
element has been represented. The Type field of the Request Source
is extensible. Initial values include a domain name, an IP address
or a trunk group.
The Type of the Route Source element is followed by a Value, which
designates the network element. The format of the identity is
determined by the Type.
5.6. Implementing Operations
This framework specifies an abstract Request/Response protocol that
enables a Client to send Requests to a Service about telephone
numbers or related telephone services. Requests may pass through one
or more Intermediaries on their way from a Client to a Service; for
example, through aggregators or service bureaus. A Client
establishes the Subject of a Request, and optionally includes one or
more Restrictions to focus the scope of the Request. When a Service
receives a Request, it performs any necessary authorization and
policy decisions based on the Source. If policy permits, the Service
generates a Response, which will consist of a Response Code and one
or more Records associated with the Subject. The Service then sends
the Response through the same path that the Request followed;
transactional identifiers set by the Client and Service correlate the
Request to the Response and assist any intermediary routing.
5.6.1. Transport Independence
The information model provided for Requests and Responses in this
framework is independent of any underlying transport or encoding.
Future specifications will define Bindings that specify particular
transports and Encodings for Requests and Responses. In some
deployment environments, for example, a binary encoding and
lightweight transport might be more appropriate than the use of a web
protocol. This specification provides a template of requirements
that must be addressed by any encoding scheme.
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It is a design goal of this work that the semantics of Requests and
Responses survive interworking through translations from one encoding
to another; for example, when an Intermediary receives a binary
Request from a Client, it should be able to transcode it to an XML
format to send to a Service without discarding any of the original
semantics.
5.6.2. Bindings
A TeRI Binding is an underlying protocol that carries Requests and
Responses. Future specifications may define Bindings in accordance
with the procedures in the IANA Considerations sections of this
document.
By underlying protocol, this specification means both transport-layer
protocols as well as any application-layer protocols that the Binding
requires. Thus an example Binding might specify a combination of
TCP, TLS, HTTP and SOAP as the underlying transport for TeRI.
Alternatively, it might only specify a very lightweight underlying
protocol like UDP. A Binding may be specific to a particular
Encoding, or it may be independent of any Encoding.
Bindings must specify whether they are continuous, transactional or
non-transactional. A continuous Binding creates a persistent
connection between two TeRI entities over which many, potentially
unrelated, Requests and Responses might flow. Many Bindings defined
for use between an Intermediary and a Service will have this
property, as Intermediaries may aggregate on behalf of many Clients,
and opening a separate transport-layer connection for each new
Request would be inefficient. A transactional Binding creates a
temporary connection between two TeRI entities for the purpose of
fulfilling a single Request; any Responses to the Request will use
the same connection to return to the sender of the Request. Finally,
a non-transactional Binding does not rely on any sort of connection
semantics: the senders of Requests and Responses will always initiate
a new instance of the Binding to send a message.
This document makes no provision for discovering the Bindings
supported by a TeRI Client, Intermediary or Service. Intermediaries
may transcode between Bindings if necessary when acting to connect a
Client and a Service, especially if the Client and Service support no
Bindings in common.
A Binding specification must enumerate all categories of metadata
required to establish a connection using a Binding. For some
Bindings, this might comprise solely an IP address and a port; for
other Bindings, this might instead require higher-layer application
identifiers like a URI. This metadata includes any identifiers
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necessary for correlating Requests to Responses in a continuous or
non-transactional Binding; any Encoding making use of these Bindings
must specify how it carries those elements.
Bindings must also describe the security services they make
available. Bindings must have a means of providing mutual
authentication, integrity and confidentiality between Clients,
Intermediaries and Services. If a Binding supports TLS, for example,
these features can be provided by using TLS in an appropriate
deployment environment.
5.6.3. Encodings
A TeRI Encoding specifies how the Request and Response are
constructed syntactically. An Encoding may be specific to a
particular Binding, or it may be specified independently of any
Binding.
An Encoding may define an object format; for example, an XML or JSON
object, described with any appropriate schemas, or an ABNF
description. An Encoding might alternatively specify a mapping of
the semantic elements of Requests and Responses on to the existing
fields of headers of a protocol, especially when that protocol has
been defined as an underlying protocol Binding. Encodings must also
define whether or not they provide a bundling feature that allows
multiple Requests to be carried within particular objects or
mappings.
Every Encoding must specify how each semantic Element Type of a
Request and Response will be represented. For all baseline TeRI
Restrictions and Element Types, the Encoding specifies whether values
will be text or binary, how they will be encoded. Many baseline
Element Types (such as telephone numbers) can appear in different
places in a TeRI message; Encodings need only specify these common
element types once. Due to the extensibility of TeRI, however,
future specifications might define Element Types that an Encoding
does not address. Profiles using those extensions and Encodings must
explain their interaction.
Encodings must also describe the security services they make
available. In particular, encodings must describe a means of
providing authentication of the Sources and Authorities of Requests
and Responses respectively, as well as an integrity check over
critical elements including the Subject of Requests and the Record of
Responses.
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[TBD - we may define more about the computation of this signature,
including canonicalization of elements, in this framework, and make
it a requirement for encodings to support this mechanism]
5.6.4. Profiles and Extension Elements
For particular deployment environments, only one Binding, Encoding
and set of Restrictions or other extended elements may be meaningful.
Future specifications may therefore define TeRI Profiles, which
describe a particular deployment environment and the Binding,
Encoding and set of Elements and Restrictions it requires.
Profiles may encompass extensions to baseline TeRI, and any new
Elements or Restrictions necessary may be defined within the Profile.
It is not necessary for a TeRI Service to understand extension
Elements that appear in Records or as Restrictions in a Query: if a
Service receives a Query with a Restriction, it can search Records
with the target Subject for Elements matching the Restriction and
return only those that apply. As such there is no formal capability
negotiation for extensions in the TeRI model: a Record may contain
Elements beyond baseline TeRI that a particular Client does not
understand and must ignore; similarly, a Service may receive a Query
with a Restriction that applies to no Records collected at the
Service, in which case the Service returns a "No Suitable Records
Exist for Restriction" Response Code.
6. Security Considerations
The framework of this document differs from previous efforts to
manage telephone numbers on the Internet largely by offering a much
richer set of security services. In particular, it requires that
three entities be capable of authenticating themselves to one another
at the layer of a binding: Clients, Intermediaries and Services. It
furthermore requires object security at the encoding layer so that
Sources and Authorities can sign data in order to authenticate
Requests and Responses that may pass through Intermediaries, and
moreover so that Authorities can prove to Clients that their Records
are authoritative even when the Authority does not operate the
Service. The requirements that bindings and encodings must satisfy
to meet these security needs are specified in Section 5.6.1.
[TBD - more]
7. IANA Considerations
This specification defines several registries: A registry of
Elements, a registry of Element Types, and a registry of Response
Codes.
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This document creates a registry of Elements for use with this
framework. This registry is extensible, with an IANA Registration
policy of Specification Required. Any new Element registered must
supply the name of the Element, the name of the parent Element in the
information model, and a code point. [TBD]
This specification pre-provisions the Element Types registry with the
entries given in Section 6. These elements are indexed by their Type
Code. This registry is extensible, with an IANA Registration policy
of Specification Required. Any new Element Type registered must
supply the name of the Element Type, the name of the parent element
in the information model, and a Type Code.
This document furthermore creates a registry of Response Codes. This
registry is pre-provisioned with the values given in Section 5.5.
[TBD]
8. Acknowledgements
The authors would like to thank Chris Wendt, Paul Kyzviat and Dale
Worley for their input into this specification.
9. Informative References
[I-D.ietf-modern-problem-framework]
Peterson, J. and T. McGarry, "Modern Problem Statement,
Use Cases, and Framework", draft-ietf-modern-problem-
framework-04 (work in progress), March 2018.
[RFC1123] Braden, R., Ed., "Requirements for Internet Hosts -
Application and Support", STD 3, RFC 1123,
DOI 10.17487/RFC1123, October 1989,
<https://www.rfc-editor.org/info/rfc1123>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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,
<https://www.rfc-editor.org/info/rfc3261>.
[RFC3324] Watson, M., "Short Term Requirements for Network Asserted
Identity", RFC 3324, DOI 10.17487/RFC3324, November 2002,
<https://www.rfc-editor.org/info/rfc3324>.
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[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private
Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks", RFC 3325,
DOI 10.17487/RFC3325, November 2002,
<https://www.rfc-editor.org/info/rfc3325>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
[RFC3966] Schulzrinne, H., "The tel URI for Telephone Numbers",
RFC 3966, DOI 10.17487/RFC3966, December 2004,
<https://www.rfc-editor.org/info/rfc3966>.
[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,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC4474] Peterson, J. and C. Jennings, "Enhancements for
Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 4474,
DOI 10.17487/RFC4474, August 2006,
<https://www.rfc-editor.org/info/rfc4474>.
[RFC4904] Gurbani, V. and C. Jennings, "Representing Trunk Groups in
tel/sip Uniform Resource Identifiers (URIs)", RFC 4904,
DOI 10.17487/RFC4904, June 2007,
<https://www.rfc-editor.org/info/rfc4904>.
[RFC4916] Elwell, J., "Connected Identity in the Session Initiation
Protocol (SIP)", RFC 4916, DOI 10.17487/RFC4916, June
2007, <https://www.rfc-editor.org/info/rfc4916>.
[RFC5039] Rosenberg, J. and C. Jennings, "The Session Initiation
Protocol (SIP) and Spam", RFC 5039, DOI 10.17487/RFC5039,
January 2008, <https://www.rfc-editor.org/info/rfc5039>.
[RFC5067] Lind, S. and P. Pfautz, "Infrastructure ENUM
Requirements", RFC 5067, DOI 10.17487/RFC5067, November
2007, <https://www.rfc-editor.org/info/rfc5067>.
[RFC5727] Peterson, J., Jennings, C., and R. Sparks, "Change Process
for the Session Initiation Protocol (SIP) and the Real-
time Applications and Infrastructure Area", BCP 67,
RFC 5727, DOI 10.17487/RFC5727, March 2010,
<https://www.rfc-editor.org/info/rfc5727>.
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[RFC5954] Gurbani, V., Ed., Carpenter, B., Ed., and B. Tate, Ed.,
"Essential Correction for IPv6 ABNF and URI Comparison in
RFC 3261", RFC 5954, DOI 10.17487/RFC5954, August 2010,
<https://www.rfc-editor.org/info/rfc5954>.
[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,
<https://www.rfc-editor.org/info/rfc6116>.
[RFC6406] Malas, D., Ed. and J. Livingood, Ed., "Session PEERing for
Multimedia INTerconnect (SPEERMINT) Architecture",
RFC 6406, DOI 10.17487/RFC6406, November 2011,
<https://www.rfc-editor.org/info/rfc6406>.
[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, <https://www.rfc-editor.org/info/rfc6461>.
[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
of Named Entities (DANE) Transport Layer Security (TLS)
Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
2012, <https://www.rfc-editor.org/info/rfc6698>.
[RFC6950] Peterson, J., Kolkman, O., Tschofenig, H., and B. Aboba,
"Architectural Considerations on Application Features in
the DNS", RFC 6950, DOI 10.17487/RFC6950, October 2013,
<https://www.rfc-editor.org/info/rfc6950>.
[RFC7095] Kewisch, P., "jCard: The JSON Format for vCard", RFC 7095,
DOI 10.17487/RFC7095, January 2014,
<https://www.rfc-editor.org/info/rfc7095>.
[RFC7340] Peterson, J., Schulzrinne, H., and H. Tschofenig, "Secure
Telephone Identity Problem Statement and Requirements",
RFC 7340, DOI 10.17487/RFC7340, September 2014,
<https://www.rfc-editor.org/info/rfc7340>.
Author's Address
Jon Peterson
Neustar, Inc.
Email: jon.peterson@team.neustar
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