DRINKS S. Channabasappa, Ed.
Internet-Draft CableLabs
Intended status: Informational May 25, 2010
Expires: November 26, 2010
DRINKS Use cases and Protocol Requirements
draft-ietf-drinks-usecases-requirements-03
Abstract
This document captures the use cases and associated requirements for
interfaces that provision session establishment data into SIP Service
Provider components, to assist with session routing. Specifically,
the current version of this document focuses on the provisioning of
one such element, termed the registry.
Status of this Memo
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Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Registry Use Cases . . . . . . . . . . . . . . . . . . . . . . 9
3.1. Category: Provisioning Mechanisms . . . . . . . . . . . . 9
3.2. Category: Interconnect Schemes . . . . . . . . . . . . . . 9
3.3. Category: SED Exchange and Discovery Models . . . . . . . 11
3.4. Category: SED Record Content . . . . . . . . . . . . . . . 12
3.5. Category: Separation and Facilitation of Data
Management . . . . . . . . . . . . . . . . . . . . . . . . 12
3.6. Category: Lookup Keys . . . . . . . . . . . . . . . . . . 13
3.7. Category: Number Portability . . . . . . . . . . . . . . . 14
3.8. Category: Misc . . . . . . . . . . . . . . . . . . . . . . 14
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 16
5. Security Considerations . . . . . . . . . . . . . . . . . . . 18
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. Normative References . . . . . . . . . . . . . . . . . . . 21
8.2. Informative References . . . . . . . . . . . . . . . . . . 21
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
This document reuses terms from [RFC3261] (e.g., SIP), [RFC5486]
(e.g., LUF, LRF, SED) and [RFC5067] (carrier-of-record and transit
provider). In addition, this document specifies the following
additional terms.
Registry: The authoritative source for provisioned session
establishment data (SED) and related information.
Registrar An entity that provisions and manages data into the
registry.
Registrant An entity whose data is provisioned into the registry.
The registrant can act as its own registrar or - additionally or
alternatively - delegate this function to a third party who acts
as its registrar.
Local Data Repository: The data store component of an addressing
server that provides resolution responses.
Public Identifier: A public identifier refers to a telephone number
(TN), an email address, or other identity as deemed appropriate,
such as a globally routable URI of a user address (e.g.,
mailto:john.doe@example.net).
TN Range: A numerically contiguous set of telephone numbers whose
SED can be looked up (resolved).
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Destination Group: An aggregation of a set of public identifiers,
TN Ranges, or RNs that share common SED.
Data Recipient: An entity with visibility into a specific set of
public identifiers, the destination groups that contain these
public identifiers, and a routing group's SED records.
Routing Group: An aggregation that contains a related set of SED
records, and is associated with a set of destination groups.
Routing groups facilitate the management of SED records - which
are common to a large number of public identifiers, TN Ranges or
RNs - for one or more data recipients.
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2. Overview
The SPEERMINT WG specifies Session Establishment Data, or SED, as the
data used to route a call to the next hop associated with the called
domain's ingress point. More specifically, the SED is the set of
parameters that the outgoing signaling path border elements (SBEs)
need to establish a session. See [RFC5486] for more details.
The specification of the format and protocols to provision SED is a
task taken up by the DRINKS WG. This document contains the use cases
and requirements that have been proposed in this regard.
SED is typically created by the terminating SSP and consumed by the
originating SSP. To avoid a multitude of bilateral exchanges, SED is
often shared via intermediary systems - termed registries within this
document. Such registries receive SED via provisioning transactions
from other SSPs, and then distribute the received data into Local
Data Repositories. These local data repositories are used for call
routing by outgoing SBEs. This is depicted in Figure 1.
*-------------*
1. Provision SED | |
-----------------------> | Registry |
| |
*-------------*
/ \
/ \
/ \
/ \
/ \
/ \
/ 2.Distribute \
/ SED \
V V
+----------+ +----------+
|Local Data| |Local Data|
|Repository| |Repository|
+----------+ +----------+
Figure 1: General Diagram
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In this version of the document, we primarily address the use cases
and requirements for provisioning registries. Future revisions may
include data distribution to local data repositories. The resulting
provisioning protocol can be used to provision data into a registry,
or between registries. This is depicted in Figure 2.
. . . . . . .
. . . . . . . registry . . . . . . .
. . . . . . . . .
. . .
. . provision .
+-----------+ . +-----------+
| | provision +----------+ provision | |
| SSP 1 |------------>| Registry |<-----------| SSP 2 |
| | +----------+ | |
| +-----+ | /\ | +-----+ |
| | LDR | <-------------------- ------------------>| LDR | |
| +-----+ | distribute distribute | +-----+ |
| | | |
+-----------+ +-----------+
. .
. . . . . . . . . . . . . . . . . . . . . . . .
(provision / distribute)
Where, LDR = Local Data Repository
Figure 2: Functional Overview
In addition, this document proposes the following aggregation groups
with regards to SED (refer to the use cases in Section 3.5 for the
rationale):
o Aggregation of public Identifiers into a destination group.
o Aggregation of SED records into a Routing Group.
The data model depicted in Figure 3 shows the various entities,
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aggregations and the relationships between them.
+---------+ +--------------+ +---------+
| Data |0..n 0..n| ROUTING | 1 0..n| SED |
|Recepient|------------| GROUP | --------------| Record |
+---------+ +--------------+ +---------+
|0..n |0..n
| |
| |
| |
|0..n |
1 +--------------+ 0..1 |
---------| DESTINATION |--------- |
| | GROUP | | |
| +--------------+ | |
| | | |
| 1| | |
| | | |
| | | |
0..n | 0..n | | 0..n |
+---------+ +---------+ +----------+ |
| RN | | TN | | Public |----
| | | Range | |Identifier| 1
+---------+ +---------+ +----------+
Figure 3: Data Model Diagram
The relationships are as described below:
- A Data Recipient object can be associated with zero or more
Routing Group objects, and a Routing Group object can refer to
zero or more Data Recipient objects.
- A Routing Group object can contain zero or more SED Record
objects, and a SED Record object can be contained in exactly one
Routing Group object.
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- A Routing Group object can be associated with zero or more
Destination Group objects, and a Destination Group object can be
associated with zero or more Routing Group objects.
- A Destination Group object can contain zero or more RN objects,
and an RN object can be contained in exactly one Destination Group
object.
- A Destination Group object can contain zero or more TN Range
objects, and a TN Range object can be contained in exactly one
Destination Group object.
- A Destination Group object can contain zero or more Public
Identifier objects, and a Public Identifier object can be
contained in exactly one Destination Group object.
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3. Registry Use Cases
This Section documents use cases related to the provisioning of the
registry. Any request to provision, modify or delete data is subject
to authorization. However, the act of authorization is considered to
be out of scope within this document.
3.1. Category: Provisioning Mechanisms
UC PROV #1 Real-Time Provisioning: Registrars have operational
systems that provision public identifiers, in association
with their SED. These systems often function in a manner
that expect or require that these provisioning activities
be completed immediately, as apposed to an out-of-band or
batch provisioning scheme that can occur at a later time.
This type of provisioning is referred to as real-time, or
on-demand provisioning.
UC PROV #2 Non-Real-Time Bulk Provisioning: Operational systems that
provision public identifiers and associated SED sometimes
expect that these provisioning activities be batched up
into large sets. These batched requests are then
processed using a provisioning mechanism that is out-of-
band and occurs at a later time.
UC PROV #3 Multi-Request Provisioning: Regardless of whether a
provisioning action is performed in real-time or not,
SSPs often perform several provisioning actions on
several objects in a single request or transaction. This
is done for performance and scalability reasons, and for
transactional reasons, such that the set of provisioning
actions either fail or succeed atomically, as a complete
set.
3.2. Category: Interconnect Schemes
UC INTERCONNECT #1 Inter-SSP SED: SSPs create peering relationships
with other SSPs in order to establish
interconnects. Establishing these interconnects
involves, among other things, communicating and
enabling the points of ingress and other SED used
to establish sessions to a set of public
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identifiers.
UC INTERCONNECT #2 Direct vs Indirect Peering: Some inter-SSP
peering relationships are created to enable the
establishment of sessions to the public
identifiers for which an SSP is the carrier-of-
record. This is referred to as direct peering.
Other inter-SSP peering relationships are created
to enable the establishment of sessions to public
identifiers for which an SSP is a transit
provider. This is referred to as indirect
peering. Some SSPs take into consideration an
SSP's role as a transit or carrier-of-record
provider when selecting a route to a public
identifier.
UC INTERCONNECT #3 Intra-SSP SED: SSPs support the establishment of
sessions between their own public identifiers,
not just to other SSPs public identifiers.
Enabling this involves, among other things,
communicating and enabling intra-SSP signaling
points and other SED that can differ from inter-
SSP signaling points and SED.
UC INTERCONNECT #4 Selective Peering (a.k.a. per peer policies):
SSPs create peering relationships with other SSPs
in order to establish interconnects. However,
SSPs peering relationships often result in
different points of ingress or other SED for the
same set of public identifiers.
UC INTERCONNECT #5 Provisioning of a delegated name server: An SSP
maintains a Tier 2 name server that contains the
NAPTR records that constitute the terminal step
in the LUF. The SSP needs to provision a
registry to direct queries for the SSP's numbers
to the Tier 2 name server. Usually queries to
the registry should return NS records, but in
cases where the Tier 2 uses a different domain
suffix from that used in the registry, CNAME and
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NS records may be employed instead.
3.3. Category: SED Exchange and Discovery Models
UC SED EXCHANGE #1 SED Exchange and Discovery using unified LUF/LRF:
When establishing peering relationships some SSPs
wish to communicate or receive points of ingress
and other SED that contain LUF and LRF.
UC SED EXCHANGE #2 SED Exchange and Discovery using LUF's Domain
Name: When establishing peering relationships
some SSPs may not wish to communicate or receive
points of ingress and other SED using a registry.
They wish to only communicate or receive domain
names resolvable via [RFC3263], and this query
will then return the points of ingress or other
SED that form the LUF.
UC SED EXCHANGE #3 SED Exchange and Discovery using LUF's
Administrative Domain Identifier: When
establishing peering relationships some SSPs may
not wish to communicate or receive points of
ingress and other SED using a registry. They
wish to only communicate or receive an
administrative domain identifier, which is not
necessarily resolvable via DNS. The subsequent
process of using that administrative domain
identifier to select points of ingress or other
SED can be SSP specific and occurs outside the
context of this protocol.
UC SED EXCHANGE #4 Co-existent SED Exchange and Discovery Models:
When supporting multiple peering relationships
some SSPs have the need to concurrently support
all three of the SED Exchange and Discovery
Models described above, for the same set of
lookup keys.
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3.4. Category: SED Record Content
UC SED RECORD #1 SED Record Content: Establishing interconnects
between SSPs involves, among other things,
communicating points of ingress, the service types
(SIP, SIPS, etc) supported by each point of
ingress, and the relative priority of each point of
ingress for each service type.
UC SED RECORD #2 Time-To-Live (TTL): For performance reasons,
querying SSPs sometimes cache SED that had been
previously looked up for a given public identity.
In order to accomplish this, SSPs sometimes specify
the TTL associated with a given SED record.
3.5. Category: Separation and Facilitation of Data Management
UC DATA #1 Separation of Provisioning Responsibility: An SSP's
operational practices often separate the responsibility
of provisioning the points of ingress and other SED, from
the responsibility of provisioning public identifiers (or
TN ranges or RNs). For example, a network engineer can
establish a physical interconnect with a peering SSP's
network and provision the associated domain name, host,
and IP addressing information. Separately, for each new
subscriber, the SSP's provisioning systems provisions the
associated public identifiers.
UC DATA #2 Destination Groups: SSPs often provision identical SED
for large numbers of public identifiers. Groups of
public identifiers that have the same SED are created.
This grouping is know as Destination Group. SED is then
indirectly associated with that group rather than to each
individual public identity.
UC DATA #3 Route Groups: SSPs often provision identical SED for
large numbers of public identifiers, and then expose that
relationship between a group of SED records and a group
of public identifiers to one or more SSPs. This combined
grouping of SED records and Destination Groups
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facilitates management of public identity SED
relationships and the list of peers (data recipients)
that can lookup those public identifiers and receive that
SED. This dual set of SED Records and Destination Groups
is termed as a Route Group.
3.6. Category: Lookup Keys
UC LOOKUP #1 Additions and deletions: SSPs often allocate and de-
allocate specific public identifiers to and from end-
users. This involves, among other things, activating
or deactivating specific public identifiers (or TN
ranges or RNs), and directly (or indirectly)
associating them with the appropriate points of ingress
and other SED.
UC LOOKUP #2 Carrier-of-Record vs Transit Lookup Key Provisioning:
Some inter-SSP peering relationships are created to
enable the establishment of sessions to the lookup keys
for which an SSP is the carrier-of-record. Other
inter-SSP peering relationships are created to enable
the establishment of sessions to lookup keys for which
an SSP is a transit provider. Some SSPs take into
consideration an SSP's role as a transit or carrier-of-
record provider when selecting a route to a public
identifier.
UC LOOKUP #3 Multiplicity of Identical Lookup Keys: As described in
previous use cases, SSPs provision lookup keys and
their associated SED for multiple peering SSPs, and as
both the carrier-of-record and transit provider. As a
result, a given lookup key can reside in multiple
destination groups at any given time.
UC LOOKUP #4 Lookup Key Destination Group Modification: SSPs often
change the SED associated with a given lookup key.
This involves, among other things, directly or
indirectly associating them with a different point of
ingress, different services, and/or different other
SED.
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UC LOOKUP #5 Lookup Key Carrier-Of-Record vs Transit Modification:
SSPs may have the need to change their Carrier-Of-
Record vs Transit role for lookup keys they previously
provisioned.
UC LOOKUP #6 Modification of authority: An SSP indicates that it is
the carrier-of-record for an existing public identity
or TN Range. If the public identity or TN Range was
previously associated with a different carrier-of-
record then there are multiple possible outcomes, such
as: a) the previous carrier-of-record is disassociated,
b) the previous carrier-of-record is relegated to
transit status, or c) the new carrier-of-record is
placed in inactive mode. The choice may be dependent
on the deployment scenario, and is out of scope for
this document.
3.7. Category: Number Portability
UC NP #1 EDITOR's NOTE: Need to clarify this further.
The SSP wishes to provide in query response to public
identifiers an associated routing number or RN. This is
the case when a set of public identifiers is no longer
associated with original SSP but have been ported to a
recipient SSP who provides access to these identifiers via
a switch on the SS7 network identified by the RN. In this
case a destination group containing all numbers that should
be routed to this RN needs to be created and the route
group associated with this DG needs to contain the RN
3.8. Category: Misc
UC MISC #1 Data Recipient Offer and Accept: When a peering
relationship is established (or invalidated) SSPs
provision (or remove) data recipients in the registry.
However, a peer may first need to accept it's role (as a
data recipient) before such a change is made effective.
Alternatively an auto-accept feature can be configured
for a given data recipient.
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UC MISC #2 Open numbering plans: In several countries, an "open
numbering plan" is used, which is such that the carrier-
of-record does not in fact know the complete number, but
instead only knows a portion of the E.164 number. The
rest of the digits are handled by a PBX off of that
carrier-of-record, and even the number of those digit is
not fixed. For example, an SSP can be the carrier-of-
record for "+123456789", and is also the carrier-of-
record for every possible expansion of that number such
as "+12345678901" and "+123456789012", even though the
SSP does not know what those expansions could be, because
the PBX decides that. This can be described as the
carrier-of-record effectively being authoritative for a
"prefix".
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4. Requirements
This Section lists the requirements based on the use cases in
Section 3. Unless explicitly stated as optional, the registry
provisioning interface must support these requirements.
REQ1: a) Real-time, b) non-real-time bulk, and c) multi-request
provisioning.
REQ2: Inter-SSP SED with support for direct and indirect peering.
REQ3: Intra-SSP SED.
REQ4: Selective peering.
REQ5: Provisioning of a delegated name server.
REQ6: The following SED Exchange and discovery models (concurrently
for the same public identifier): a) unified LUF/LRF, b) LUF-
only with domain name, and c) LUF-only with administrative
domain.
REQ7: Provisioning of SED Record content
REQ8: (Optional) Communicate the TTL for a given SED Record.
REQ9: Separation of responsibility of provisioning the points of
ingress and other SED, from the responsibility of
provisioning public identifiers.
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REQ10: Additions and deletions of public identifiers, TN ranges and
RNs.
REQ11: Provisioning of, and modifications to, the following
aggregations: destination group and route groups.
REQ12: Support the distinction between an SSP as a carrier-of-record
provider versus transit provider.
REQ13: Support for lookup keys having identical business keys (the
public identity string, the digits that comprise an RN, the
start and end point of a TN range's range) that concurrently
exist across multiple destination groups and where each
destination group may be managed by different SSPs.
Editor's note: We need to simplify the above requirement.
REQ14: Modification of lookup keys by allowing them to be moved to a
different destination group via an atomic operation.
REQ15: SSPs to change their Carrier-Of- Record vs Transit role.
REQ16: Support for modification of authority with the conditions
described in UC LOOKUP #6.
REQ17: Destination group offer and acceptance (optionally support
auto-acceptance).
REQ18: Open numbering plans.
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5. Security Considerations
Session establishment data allows for the routing of SIP sesions
within, and between, SIP Service Providers. Access to this data can
compromise the routing of sessions and expose a SIP Service Provider
to attacks such as service hijacking and denial of service. The data
can be compromised by vulnerable functional components and interfaces
identified within the use cases.
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6. IANA Considerations
This document does not register any values in IANA registries.
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7. Acknowledgments
This document is a result of various discussions held by the DRINKS
requirements design team, which is comprised of the following
individuals, in alphabetical order: Deborah A Guyton (Telcordia),
Gregory Schumacher (Sprint), Jean-Francois Mule (CableLabs), Kenneth
Cartwright (TNS, Inc.), Manjul Maharishi (TNS, Inc.), Penn Pfautz
(AT&T Corp), Ray Bellis (Nominet), the co-chairs (Richard Shockey,
Nuestar; and Alexander Mayrhofer, enum.at GmbH), and the editors of
this document.
This specific version of the document is a result of contributions
from, primarily, David Schwartz (XConnect), Kenneth Cartwright (TNS,
Inc.) and Syed Ali (Neustar, Inc.). Other participants who reviewed
and provided comments include: Alexander Mayrhofer (enum.at GmbH),
Jean-Francois Mule (CableLabs), Manjul Maharishi (TNS, Inc.), Hadriel
Kaplan (Acme Packet) and other participants on the DRINKS mailing
list.
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8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
8.2. Informative References
[RFC3261] 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.
[RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation
Protocol (SIP): Locating SIP Servers", RFC 3263,
June 2002.
[RFC5067] Lind, S. and P. Pfautz, "Infrastructure ENUM
Requirements", RFC 5067, November 2007.
[RFC5486] Malas, D. and D. Meyer, "Session Peering for Multimedia
Interconnect (SPEERMINT) Terminology", RFC 5486,
March 2009.
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Author's Address
Sumanth Channabasappa
CableLabs
858 Coal Creek Circle
Louisville, CO 80027
USA
Email: sumanth@cablelabs.com
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