One document matched: draft-peterson-modern-problems-01.txt
Differences from draft-peterson-modern-problems-00.txt
Network Working Group J. Peterson
Internet-Draft T. McGarry
Intended status: Informational NeuStar, Inc.
Expires: January 7, 2016 July 6, 2015
Modern Problem Statement, Use Cases, and Framework
draft-peterson-modern-problems-01.txt
Abstract
The functions of the public switched telephone network (PSTN) are
gradually migrating to the Internet. This is generating new
requirements for many mechanisms used on the PSTN, including
telephone numbers (TNs). TNs no longer serve simply as telephone
routing addresses, they are now identifiers which may be used by
Internet-based services for a variety of purposes including session
establishment, identity verification, and service enablement. This
problem statement examines how the existing tools for allocating and
managing telephone numbers do not align with the needs of the
Internet environment and proposes a framework for Internet-based
services relying on TNs.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 7, 2016.
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Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Provisions Relating to IETF Documents
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Table of Contents
1. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 2
2. Actors . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Framework . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Acquiring Telephone Numbers . . . . . . . . . . . . . . . 6
4.1.1. CSP Acquires Numbers from Registry . . . . . . . . . 6
4.1.2. User/Delegate Acquires TNs from CSP . . . . . . . . . 7
4.1.3. User Acquires TNs from a Delegate . . . . . . . . . . 8
4.1.4. User Acquires Numbers from Registry . . . . . . . . . 8
4.2. Accessing Numbering Information . . . . . . . . . . . . . 8
4.2.1. Service Information Access . . . . . . . . . . . . . 8
4.2.2. Privileged Access for Government Entities . . . . . . 9
4.3. Service Management for Numbers . . . . . . . . . . . . . 9
4.3.1. Updating Service Information . . . . . . . . . . . . 9
4.3.2. Updating Administrative Information . . . . . . . . . 10
4.3.3. Changing the CSP for an Existing Communications
Service . . . . . . . . . . . . . . . . . . . . . . . 10
4.3.4. Terminating a Service . . . . . . . . . . . . . . . . 10
5. Distributed Registries and Data Stores . . . . . . . . . . . 11
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. Informative References . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Problem Statement
The challenges of utilizing telephone numbers (TNs) on the Internet
has been known for some time. Internet telephony provided the main
use case for routing telephone numbers on the Internet in a manner
similar to how calls are routed in the public switched telephone
network (PSTN). As the Internet had no service for discovering the
endpoints associated with telephone numbers, ENUM [3] created a DNS-
based mechanism for resolving TNs in an IP environment, by defining
procedures for translating TNs into URIs for use by protocols such as
SIP [2]. Originally, it was envisioned that ENUM would be deployed
as a global hierarchical service, though in practice, it has only
been deployed piecemeal by various parties. Most notably, ENUM is
used as an internal network function, and is hardly used between
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service provider networks. The original ENUM concept of a single
root, e164.arpa, proved to be politically challenging, and less
centralized models have thus flourished.
Subsequently, the DRINKS [4] framework showed ways that authorities
might provision information about telephone numbers at an ENUM
service or similar Internet-based directory. These technologies have
generally tried to preserve the features and architecture familiar
from the PSTN numbering environment.
Telephone numbering, however, has long been transitioning away from a
provider-centric model towards a user-centric model. Number
portability has been implemented in many countries, and the right of
a user to choose and change their service provider while retaining
their TN is widely acknowledged now. However, TN administration
processes rooted in PSTN technology and policies dictate that this be
an exception process fraught with problems and delays. Thanks to the
increasing sophistication of consumer mobile devices, users now
associate telephone numbers with many applications other than
telephony. Ideally the user would have full control of their TN and
would drive the porting process on their own rather than rely on
complex and time consuming back office processes among multiple
service providers.
Most TNs today are assigned to specific geographies, at both an
international level and within national numbering plans. This has
shaped the way that service providers interconnect, as well as how
telephone numbers are routed and administered: the PSTN was carefully
designed to delegate switching intelligence geographically. In
interexchange carrier routing in North America, for example, calls to
a particular TN are often handed off to the terminating service
provider close to the geography where that TN is assigned. But the
overwhelming success of mobile telephones has increasing eroded the
connection between numbers and regions. Furthermore, the topology of
IP networks is not anchored to geography in the same way that the
telephone network is. In an Internet environment, establishing a
network architecture for routing telephone numbers would depend
little on geography. Adapting telephone numbers to the Internet
requires more security, richer datasets and more complex query and
response capabilities than previous efforts have provided.
With the PSTN well on its way to transitioning to an all IP network,
and TNs showing no signs of sunsetting as a resource, it is time to
address the issues of routing, management and administration of TNs
in an IP environment. This document will create a common
understanding of the problem statement related to TNs in an IP
environment and help develop a vision for how to create IP-based
mechanisms for TNs. It will be important to acknowledge that there
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are various international and national policies and processes related
to TNs, and any solutions need to be flexible enough to account for
these variations.
2. Actors
The following actors are defined in this document:
Numbering Authority: A regulatory body within a country that manages
that country's telephone numbers. The numbering authority decides
national numbering policy, including what telephone numbers can be
allocated, and which are reserved.
Registry: An entity that administers the allocation of telephone
numbers based on a numbering authority's policies. Numbering
authorities can act as the registries themselves, or they can
outsource the function to other entities. A registry can act as a
sole authoritative entity for a numbering authority, or there can
also be multiple registries that manage the same telephone numbers
and synchronize with each other.
Communication Service Provider: A provider of communications
services to users, where those services can be identified by
telephone numbers. This includes both traditional telephone
carriers or enterprises as well as service providers with no
presence on the PSTN who use telephone numbers. This framework
does not assume that any single CSP provides all the
communications service related to a TN.
Service Enabler: An entity that works with CSPs to enable
communication service to a user; perhaps a vendor, or third-party
integrator.
User: An individual reachable through a communications service;
usually a customer of a communication service provider who uses
telephone numbers to reach and identify services. Sophisticated
users may also act as their own CSPs.
Government Entity: An entity that, due to legal powers deriving from
national policy, has privileged access to information about number
administration under certain conditions.
Note that a given entity may act in one or more of the roles above.
An entity acting as a Communications Service Provider, Service
Enabler, or User can also be said to have a relationship to the
registry of either an assignee or delegate:
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Assignee.: An entity that is assigned the telephone number by the
registry. There is a direct relationship between the registry and
the assignee.
Delegate: An entity that is delegated a telephone number from an
assignee or another delegate for assignment or delegation to
others. A delegate is not the assignee or the user.
Note that although numbering authorities are listed as actors, they
are unlikely to actually participate in the protocol flows
themselves.
3. Framework
The framework outlined in this document requires three Internet-based
mechanisms for managing and resolving telephone numbers (TNs) in an
IP environment. These mechanisms will likely reuse existing
protocols for sharing structured data; it is unlikely that new
protocol development work will be required, though new information
models specific to the data itself will be a major focus of framework
development. Likely candidates for reuse here include work done in
DRINKS and WEIRDS, as well as the TeRQ [12] framework.
These protocol mechanisms are scoped in a way that makes them likely
to apply to a broad range of future policies for number
administration. It is not the purpose of this framework to dictate
number policy, but instead to provide tools that will work with
policies as they evolve going forward. These mechanisms therefore do
not assume that number administration is centralized, nor that number
"ownership" is restricted to any privileged service providers, though
these tools must and will work in environments with those properties.
The three mechanisms are:
Acquisition: a protocol mechanism to enable users or CSPs to acquire
TNs from authorities, including an enrollment process for the
individuals and entities that manage TNs.
Management: a protocol mechanism for users to associate data with
TNs at a CSP.
Retrieval: a protocol mechanism for service providers, users, and
government entities to retrieve data about TNs from either an
authority or a CSP.
The acquisition mechanism will enable actors to acquire telephone
numbers for use with a communications service. The acquisition
mechanism will provide a means for either a user or a CSP to request
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numbering resources from an authority, either on a number-by-number
basis, or as inventory blocks. The authority who grants numbering
resources to a user will retain metadata about the assignment,
including the responsible organization or individual to whom numbers
have been assigned. In the DNS environment, an authority thus might
be analogous to either a registrar or a reseller of names, though
obvious hierarchical domain names do not have a comparable inventory
situation to telephone numbers.
The management mechanism will let actors provision data associated
with telephone numbers at CSPs. If a user owns a telephone number,
they may select a CSP to provide a particular service associated with
the number, or a CSP may own a number, and effectively rent these to
users. In either case, a user needs a mechanism to provision data
associated with the number at a CSP.
The resolution mechanism will enable actors to learn information
about telephone numbers, typically by sending a request to a CSP.
For some information, an actor may need to send a request to a
numbering authority rather than a CSP. Different parties may be
authorized to receive different information about telephone numbers.
4. Use Cases
The high-level use cases in this section will provide an overview of
the expected operation of the three protocols in the MODERN problem
space.
4.1. Acquiring Telephone Numbers
There are various scenarios for how TNs can be acquired by the
relevant actors; registry, CSP, delegate, service enabler, and user.
The registry perform its functions as defined by the national
authority, so the national authority does not participate in the
protocol flows in this section.
4.1.1. CSP Acquires Numbers from Registry
Through some out-of-band business process, a CSP develops a
relationship with a Registry. The Registry has a profile of the CSP
and what qualifications they possess for requesting TNs. The CSP may
then request TNs from within a specific pool of numbers in the
authority of the Registry; such as region, mobile, wireline,
tollfree, etc. The Registry must authenticate and authorize the CSP,
and then either grant or deny a request. When an assignment occurs,
the registry stores information related to the assignment including
the resource and the assignee, and removes the specific TN(s) from
the pool of those that are available for assignment. As a part of
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the assignment process, the Registry provides credentials (for
example, STIR certificates [13]) to the CSP to be used to prove the
assignment for future transactions
Before it is eligible to receive number assignments, per the policy
of a national authority, the CSP may need to have submitted (again,
through some out-of-band process) additional qualifying information
such as current utilization rate or a demand forecast.
There are two scenarios under which a CSP requests resources; they
are requesting inventory, or they are requesting for a specific user
or delegate. If they are requesting for a user or delegate they may
need to register information about the user or delegate with the
Registry. Examples of user and delegate information could be contact
information that may be required by Government Entities, or some
forms of service information. Such data could be provided to the
Registry or the Registry could be provided with an address where that
data can be accessed. Such an address could be part of the CSP
profile with the Registry.
4.1.2. User/Delegate Acquires TNs from CSP
A User or Delegate creates or has a relationship with the CSP, and
subscribes to a communications service which includes the use of a
telephone number. The CSP first collects and stores profile data
about the User or Delegate. The CSP then activates the User or
Delegate on their network and creates any necessary service data to
enable interoperability with other CSPs. The CSP could also update
public or privileged databases accessible by other Actors. The CSP
provides a credential to the User or Delegate (for example, a STIR
certificate [13]) to prove the assignment for future transactions.
The credential could be delegated from the one provided by the
Registry to the CSP in a continuing the chain of assignment.
The CSP could assign a TN from its existing inventory or it could
acquire it from the Registry as part of the assignment process. If
it assigns it from its existing inventory it would remove the
specific TN from the pool of those available for assignment. It may
also update the registry about the assignment so the registry has
current utilization data. If TNs are assigned to a Delegate for use
as inventory to be assigned to Users, the Delegate may need to
provide utilization data to the Registry, either directly or through
the CSP.
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4.1.3. User Acquires TNs from a Delegate
This follows the process in Section 4.1.2, as it should be similar to
how a User acquires TNs from a CSP. In this case, the Delegate would
be performing functions done by the CSP, e.g., providing credentials,
updating the Registry, and so on.
4.1.4. User Acquires Numbers from Registry
This follows the process in Section 4.1.1, as it should be similar to
how a CSP acquires TNs from a Registry. In this case, the user must
establish some business relationship directly to a registry, perhaps
similarly to how such functions are conducted today when users
purchase domain names. TNs assigned to a user are always considered
assigned by the Registry, not inventory.
In this use case, after receiving a number assignment from the
Registry, a User will then obtain communications service from a CSP,
and provide to the CSP the TN to be used for that service. The CSP
will associate service information for that TN, e.g., service
address, and make it available to other CSPs to enable
interoperability.
4.2. Accessing Numbering Information
Telephone numbering information will generally fall into two
categories; administrative information and service information.
Administrative information includes TN status, service provider,
contact data, etc. and typically does not require real-time
performance. Service information includes addressing data, feature
capabilities, etc. and typically does require real-time performance.
Telephone numbering data can be stored at the Registry or at the CSP
that holds the information. The address for accessing the
information would need to be available to others to enable access and
interoperability. For example, if the data is held by the Registry,
a URL for accessing that data could be published to those that have
access to the Registry. The Registry could allow and restrict access
to specific information based on the identity of requestor. If the
data is held by a CSP, the Registry could host an address for each TN
that references the correct CSP, and the CSP would allow or restrict
access based on the requestor.
4.2.1. Service Information Access
A gateway receives a call for a telephone number. That telephone
number is assigned to a CSP, who has delegated to the number to a
User. The gateway wants to reach the User through an Internet
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communications endpoint. It therefore send a query to the Registry
responsible for the numbering space that the telephone number resides
in. The Registry proxies or redirects the request to the CSP that
has been assigned the number. The CSP returns Internet endpoint
information for that number to the gateway, possibly after making an
authorization decision.
In an alternative use case, the CSP might provision the Registry with
endpoint service information for the telephone number, or the CSP
might have delegated to the User the responsibility for provisioning
this information with the Registry.
4.2.2. Privileged Access for Government Entities
In this case, a Government Entity wishes to access information about
a particular User, who subscribes to a communications service. The
entity that operates the Registry on behalf of the National Authority
in this case has some pre-defined relationship with the Government
Entity. When the CSP acquired TNs from the National Authority, it
was a condition of that assignment that the CSP provide access for
Government Entities to telephone numbering data when certain
conditions apply. The required data may reside either in the CSP or
in the Registry.
For a case where the CSP delegates a number to the User, the CSP
might provision the Registry with information relevant to the User.
At such a time as the Government Entity needs information about that
User, the Government Entity may contact the Registry or CSP to
acquire the necessary data. The interfaces necessary for this will
be the same as those described in Section 4.2; the Government Entity
will be authenticated, and an authorization decision will be made by
the Registry or CSP under the policy dictates established by the
National Authority.
4.3. Service Management for Numbers
The use cases in this section describe ways that numbering data,
including administrative information and service information, might
be updated at the CSP or Registry after a number has been initially
assigned and provisioned.
4.3.1. Updating Service Information
A CSP handles all users in a large region through a central set of
proxy servers. They provision a URL pointing to that service in the
Registry. After a business transition, the CSP wants to point the
service to a new URL. The CSP therefore sends a provisioning update
to the Registry.
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While some similar use cases may apply to individual Users, it is
anticipated that for the most part these lower-level service
information changes would be communicated via existing protocols
(like the baseline [2] SIP REGISTER method) rather than through any
interfaces defined by MODERN.
4.3.2. Updating Administrative Information
A User who subscribes to a communications service changes their
postal address, moving from one location in the country to another.
At this time, the User informs the CSP. The CSP updates its own
records, and send an update to the Registry as well, as the National
Authority in this case requires that the CSP notify the Registry of
changes in the contact information associated with numbering
resources.
4.3.3. Changing the CSP for an Existing Communications Service
A User who subscribes to a communications service, and received their
TN from that CSP, wishes to retain the same TN but move their service
to a different CSP.
Depending on the policies set by the National Authority, it might be
the responsibility of either the old or new CSP to initiate the
transition process. The new CSP will then provision the registry
with the new service and administrative information associated with
the CSP, though much of the administrative information relating to
the User may remain the same through this transition. The CSP will
perform other functions described above in Section 4.1.2.
At this time, the old CSP will undo any delegations to the User,
including invalidating any cryptographic credentials (e.g. STIR
certificates [13]) previously granted to the user. Any routing or
service information maintained by the CSP must be removed, and
similarly, the CSP must delete any such information it provisioned in
the Registry.
[TBD - more on the case where multiple CSPs provide services for a
given TN, and only one service is "ported" to a new CSP?]
4.3.4. Terminating a Service
This use case is very similar to that in Section 4.3.3. A User who
subscribes to a communications service, and received their TN from
the CSP, wishes to terminate their service. At this time, the CSP
will undo any delegations to the User, including invalidating any
cryptographic credentials (e.g. STIR certificates [13]) previously
granted to the user. Any routing or service information maintained
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by the CSP must be removed, and similarly, the CSP must delete any
such information it provisioned in the Registry.
In an alternative use case, a User who received their own TN
assignment directly from the Registry terminates their service with a
CSP. At this time, the User might terminate their assignment from
the Registry, and return the number to the Registry for re-
assignment. Alternatively, they could retain the number and elect to
assign it to some other service at a later time.
5. Distributed Registries and Data Stores
It is possible to create a distributed Registry or distributed Data
Stores for the administrative and service information associated with
a TN.
In a distributed Registry there would be multiple duplicate copies of
the Registry data. A CSP or User would interact with one Registry
and that Registry would be responsible for initiating updates to all
other Registries when there is a change. The challenge is to ensure
that there are no clashes, e.g., two Registries assigning the same TN
to two different CSPs.
Similarly multiple entities can maintain duplicate copies of
administrative and service data associated with TNs. For example,
when a CSP enables service for a User they can initiative an update
of the service address to multiple other data stores managed by other
service providers. This may not be the best solution for User
contact data.
[More TBD]
6. Acknowledgments
We would like to thank Henning Schulzrinne for his contributions to
this problem statement and framework.
7. IANA Considerations
This memo includes no request to IANA.
8. Security Considerations
TBD.
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9. Informative References
[1] Peterson, J. and C. Jennings, "Enhancements for
Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 4474, August 2006.
[2] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[3] Bradner, S., Conroy, L., and K. Fujiwara, "The E.164 to
Uniform Resource Identifiers (URI) Dynamic Delegation
Discovery System (DDDS) Application (ENUM)", RFC 6116,
March 2011.
[4] Channabasappa, S., "Data for Reachability of Inter-/Intra-
NetworK SIP (DRINKS) Use Cases and Protocol Requirements",
RFC 6461, January 2012.
[5] Watson, M., "Short Term Requirements for Network Asserted
Identity", RFC 3324, November 2002.
[6] Jennings, C., Peterson, J., and M. Watson, "Private
Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks", RFC 3325,
November 2002.
[7] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
of Named Entities (DANE) Transport Layer Security (TLS)
Protocol: TLSA", RFC 6698, August 2012.
[8] Elwell, J., "Connected Identity in the Session Initiation
Protocol (SIP)", RFC 4916, June 2007.
[9] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC
3966, December 2004.
[10] Rosenberg, J. and C. Jennings, "The Session Initiation
Protocol (SIP) and Spam", RFC 5039, January 2008.
[11] 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, March 2010.
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[12] Peterson, J., "A Framework and Information Model for
Queries about Telephone-Related Queries (TeRQ)", draft-
peterson-terq-03 (work in progress), February 2013.
[13] Peterson, J., "Secure Telephone Identity Credentials:
Certificates", draft-ietf-stir-certificates-01 (work in
progress), March 2015.
[14] Barnes, M., Jennings, C., Rosenberg, J., and M. Petit-
Huguenin, "Verification Involving PSTN Reachability:
Requirements and Architecture Overview", draft-jennings-
vipr-overview-06 (work in progress), December 2013.
[15] Rosenberg, J. and H. Schulzrinne, "Session Initiation
Protocol (SIP): Locating SIP Servers", RFC 3263, June
2002.
Authors' Addresses
Jon Peterson
Neustar, Inc.
1800 Sutter St Suite 570
Concord, CA 94520
US
Email: jon.peterson@neustar.biz
Tom McGarry
Neustar, Inc.
1800 Sutter St Suite 570
Concord, CA 94520
US
Email: tom.mcgarry@neustar.biz
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