ETSI TS 102 990 V1.1.1 (2012-11)

Technical Specification
Media Content Distribution (MCD);
CDN Interconnection, use cases and requirements

2 ETSI TS 102 990 V1.1.1 (2012-11)

Reference
DTS/MCD-00013
Keywords
audio, broadcast, CDN, content, interconnection,
IP, multimedia, regulation, TV, video
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3 ETSI TS 102 990 V1.1.1 (2012-11)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definitions and abbreviations . 6
3.1 Definitions . 6
3.2 Abbreviations . 7
4 Overview of CDN interconnection services . 8
4.1 Functional roles and CDN Relationships . 8
4.2 MCD CDN Interconnection services . 9
4.2.1 General . 9
4.2.2 Upstream CDN Provider CDN interconnection services . 9
4.2.3 Downstream CDN Provider CDN interconnection services . 10
4.2.4 Guiding principle for CDN Interconnection . 10
4.3 Compliance. 10
5 Service requirements . 11
5.1 General . 11
5.2 Service Types . 11
6 Technical requirements . 11
6.1 General . 11
6.2 CDN interconnection interfacing between Upstream CDN Provider and Downstream CDN Provider . 12
6.3 Transcoding . 13
6.4 CDN-I Security Requirements . 13
6.4.1 Integrity Requirements . 13
6.4.2 Authenticity Requirements . 13
6.4.3 Authorization Requirements . 13
6.4.4 Confidentiality Requirements . 14
6.4.5 Denial of Service Protection Requirements . 14
6.4.6 Digital rights management (DRM) . 14
6.5 Retrieving content identification . 14
6.6 Resolving content location . 14
6.7 Reporting . 15
6.8 Topology and topology hiding . 16
Annex A (informative): CDN Interconnection use cases . 17
A.1 General . 17
A.2 Consumer use cases . 17
A.2.1 Popular global content . 17
A.2.2 Popular remote content . 17
A.2.3 Quality Improvements Derived from IETF draft [i.1] . 17
A.2.3.1 Network Service Provider CDN Service Provider Use Case . 17
A.2.4 Offload use cases derived from IETF draft [i.1]. 18
A.2.4.1 Overload handling and dimensioning . 18
A.2.4.2 Resilience . 18
A.2.5 Footprint Extension Use Cases Derived from IETF draft [i.1] . 18
A.2.5.1 CDN Interconnection inside one CDN Service Provider . 18
A.2.5.2 CDN Interconnection between CDN Service Providers . 18
A.2.6 Popular segments . 18
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4 ETSI TS 102 990 V1.1.1 (2012-11)
A.2.6.1 Popular time segments . 19
A.2.6.2 Popular video tiles . 19
A.2.6.3 Scalable and multi-rate video. 19
A.3 Topology use cases . 19
A.3.1 Primary and secondary CDN . 19
A.3.2 CDN Peering . 19
A.3.3 CDN Federation . 19
A.3.4 More than two CDN hierarchy . 20
A.3.5 CDN to multicast . 20
A.3.6 Segmented content . 20
A.4 Other use cases . 20
A.4.1 Delivery Format Adaptation . 20
A.4.2 Support for HTTP Adaptive streaming . 21
Annex B (informative): Architectural approaches . 22
B.1 Generic architecture for CDN interconnection . 22
B.2 Example procedure for a content request . 23
B.3 Usage information . 25
B.4 Access networks in the CDN architecture . 25
B.5 Procedure for content distribution . 26
B.6 Content delivery through CDN Interconnection . 27
Annex C (informative): A metaphor for the electronic content delivery ecosystem . 29
C.1 General . 29
C.2 The newspaper-distribution ecosystem . 29
C.3 The content-delivery ecosystem . 31
Annex D (informative): Advanced use cases . 34
D.1 General . 34
D.2 Caching - CDN Interconnection . 34
D.3 Information-centric networking and CDN interconnection. 34
D.3.1 Background . 34
D.3.2 Comparison of ICN and CDNs . 35
D.3.2.1 Objectives . 35
D.3.2.2 Technical approach . 35
D.3.2.3 Deployment. 35
D.3.2.4 Business models . 36
D.3.3 Interconnection of ICN and CDNs . 36
History . 37

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5 ETSI TS 102 990 V1.1.1 (2012-11)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Media Content Distribution
(MCD).
Introduction
Content Delivery Networks (CDN) are a solution to efficiently deliver content Consumers, including file-based and
streaming video and multimedia content. An IPTV Service Provider uses CDN technology for content delivery to its
own Consumer customers, see TS 182 019 [1]. A CDN Service Provider uses CDN technology to deliver content to
Consumers on behalf of a Content Provider, see TR 102 688-9 [i.2].
Annex A of the present document presents several use cases where different CDN Service Provider would collaborate
and interconnect to provide a better and more efficient CDN service to their Content Provider customers. Annex C uses
the metaphor of newspaper distribution where Printer Companies collaborate to achieve a better and more efficient
newspaper distribution service to Newspaper Companies.
Based on those use cases, the present document specifies functional roles and CDN relationships, service requirements
and technical requirements for CDN interconnection.
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6 ETSI TS 102 990 V1.1.1 (2012-11)
1 Scope
The present document specifies the (stage-1) service- and technical requirements for CDN interconnection services. The
requirements are based on the use cases described in annex A of the present document.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] ETSI TS 182 019: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Content Delivery Network (CDN) Architecture".
[2] ETSI TS 184 009: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Rules covering the use of TV URIs for the Identification of
Television Channels".
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] IETF Use Cases for Content Distribution Network Interconnection: draft-ietf-cdni-use-cases.
NOTE: Available at http://tools.ietf.org/wg/cdni/draft-ietf-cdni-use-cases/
[i.2] ETSI TR 102 688-9: "Media Content Distribution (MCD); MCD framework; Part 9: Content
Delivery Infrastructures (CDI)".
[i.3] ISO/IEC 23009-1:2012 "Information technology -- Dynamic adaptive streaming over HTTP
(DASH) -- Part 1: Media presentation description and segment formats".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
The following definitions are from TS 182 019 [1]:
content delivery: act of delivering deployed content to a user
Content Delivery Network (CDN): set of functions managing content acquired from content sources, through delivery
to the user
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7 ETSI TS 102 990 V1.1.1 (2012-11)
content acquisition: act of acquiring content from a content source
content deployment: act of moving ingested content to one or more network entities, based on content deployment
policies
content distribution: act of moving content in and between CDNs
CDN interconnection: interconnection between two CDNs, enabling the controlled distribution of content between
those CDNs
The following definitions are from TR 102 688-9 [i.2]:
content ingestion: act of introducing content (and associated data) into the Content Delivery Infrastructure
segmented content: consisting of multiple mutually associated content files and/or - streams
NOTE: The association between the segments are typically communicated through a manifest file.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CDN Content Delivery Network
NOTE: Industry uses sometimes "Content Distribution Network".
DRM Digital Rights Management
FTP File Transfer Protocol
GB GigaByte
HAS HTTP-based Adaptive Streaming
HTTP HyperText Transfer Protocol
IPTV Internet Protocol TeleVision
OIPF Open IPTV Forum
RTP Real-time Transport Protocol
RTCP RTP Control Protocol
SLA Service Level Agreement
SVC Scalable Video Coding
URI Uniform Resource Identifier
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8 ETSI TS 102 990 V1.1.1 (2012-11)
4 Overview of CDN interconnection services
4.1 Functional roles and CDN Relationships
For the purpose of the present document, concepts of domains, functional roles and CDN relationships are defined in
this clause and are illustrated in figure 4.1.1.
Content ingestion
Content delivery
Consumer CDN Content
Domain Domain Domain
Ingesting
Content
CDN Service
Provider
Provider
Upstream
Transiting
Downstream
CDN Service
Provider
Upstream
Delivering
Consumer Downstream
CDN Service
Provider
Consumable Replica Mastercopy
: Direction of content flow
Figure 4.1.1: Functional roles, domains and CDN Provider relationships
for CDN interconnection
Functional roles are defined with respect to a given delivery act (i.e. the actual delivery of a given piece of content to a
given user at a given time). The functional roles are described as follows:
The Ingesting CDN provider is the entity that ingests the content ("mastercopy") into the CDN Domain. It has a CDN
interconnection with the Delivering CDN Provider (or a Transiting CDN Provider) that enables the controlled
distribution of content from the ingesting CDN to the delivering CDN.
The Delivering CDN provider is the entity that delivers the content ("consumable") into the Consumer Domain. It has
a CDN interconnection with the Ingesting CDN Provider (or a Transiting CDN Provider) that enables the controlled
distribution of content from the ingesting CDN to the delivering CDN.
A Transiting CDN provider is an entity that distributes the content ("replica") from a CDN (that maybe the Ingesting
CDN or a Transiting CDN) to another CDN (that may be the Delivering CDN or a Transiting CDN). For a given
delivery act zero, one or more Transiting CDNs may be involved.
NOTE: The terms "mastercopy", "replica" and "consumable" relate to the role of the content throughout the
process (see also annex C).
The Consumer is the entity where the content is consumed. The content is delivered through the CDN domain.
The Content Provider is the entity that owns or is licensed to sell content or content assets. The content is delivered to
a user through the CDN Domain. The Content Provider is authoritative with respect to control of consumer access to the
content (i.e. whether a given delivery request from a consumer is to be honoured by the CDN domain or not).
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9 ETSI TS 102 990 V1.1.1 (2012-11)
The present document focuses on the CDN interconnection between CDN Providers collaborating to achieve content
delivery. The present document defines the following relationships between two CDN Providers participating in a given
delivery act:
A CDN Provider is Upstream of another CDN Provider if the content is distributed from that CDN to the other CDN.
A CDN Provider is Downstream of another CDN Provider if the content is obtained by that CDN from the other CDN.
Because functional roles are relative to a given delivery act, in practice, a given entity may be performing more than
one functional role. For example, a given administrative entity could be operating as the Ingesting CDN Provider for a
given delivery act, operating as the Delivering CDN Provider for another delivery act and operating as a Transiting
CDN Provider for yet another delivery act. Similarly, it could also be operating as the Content Provider or Consumer
for some other delivery act. For the same reason, a CDN Provider that is Upstream of another CDN Provider for a given
delivery act could be Downstream of this other CDN Provider for another delivery act, and may have no
Upstream/Downstream relationship with that same other CDN Provider for yet another delivery act.
The following business- and/or technical relationships are outside the scope of the present document.
• Consumer - Content Provider: e.g. content selection and content purchase/rental
• CDN Provider - Content Provider: e.g. content ingestion
• Consumer - CDN Provider: e.g. redirection instructions and the actual content delivery
4.2 MCD CDN Interconnection services
4.2.1 General
This clause describes CDN interconnection services at a high level. It focuses on the CDN interconnection services
delivered between the Upstream CDN Provider and the Downstream CDN Provider. Services to the Consumer and
Content Provider are outside the scope of the present document.
4.2.2 Upstream CDN Provider CDN interconnection services
The following is a list CDN interconnection services that could be provided by the Upstream CDN Provider.
• Content acquisition and distribution services:
- Ingest or acquire content on behalf of a Downstream CDN Provider, in association with a Content
Provider or Transiting CDN
- Distribute content to the Downstream CDN Provider, in association with a Content Provider
• Delivery Control Services:
- Establish agreements on delivery attributes, with the Downstream CDN Provider
- Provide real-time control over ongoing deliveries, in association with the Downstream CDN Provider
• Reporting services:
- Report on the distributed content to the Downstream Content Provider
� E.g. GB stored, GB distributed, traffic over time
- Support of reporting by the Downstream CDN Provider
� E.g. storage, processing and relay of reports to the content provider
• Transit services
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4.2.3 Downstream CDN Provider CDN interconnection services
The following is a list CDN interconnection services that could be provided by the Downstream CDN Provider.
• Content delivery services:
- Provide access for content distribution to the Upstream CDN Provider
- Deliver content on behalf of the Upstream CDN Provider
• Delivery Control Services:
- Establish agreements on delivery attributes, with the Upstream CDN Provider
- Provide real-time control over ongoing deliveries, in association with the Upstream CDN Provider
• Reporting services:
- Report on the delivered content to the Upstream CDN Provider
� E.g. GB stored, GB distributed, traffic over time
• Transit services
4.2.4 Guiding principle for CDN Interconnection
Acceptance of CDN interconnection by the Content Provider is essential to successful deployment of CDN
interconnection services. The following are guiding principles to highlight that the Content Provider is in control of
anything that happens with or around the Content Provider's content within the interconnected CDN as if it were the
Content Provider's own distribution network. Subject to business agreements between service providers, as well as local
and regional regulatory requirements, in general, the principle of "as if it were the Content Provider's own distribution
network" may apply to the following aspects:
• Ownership of the content
• Distribution of the content
• Delivery of the content
• Reporting on ongoing and past deliveries of the content
• Guaranteeing the integrity of the Content Provider's content
• Satisfying local and regional regulatory requirements on user privacy
• Satisfying local and regional regulatory requirements on legal intercept
4.3 Compliance
A CDN interconnection solution is compliant to the present document if the following points are fulfilled.
• All mandatory ("shall") services and features are implemented as specified in the associated architecture and
protocol documents.
• If an optional service ("should") or feature is implemented, then it is implemented as specified in the
associated architecture and protocol documents.
• If an optional service or feature is implemented, and the associated architecture and protocol documents
specify multiple options, then it is implemented according to at least one or those options.
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11 ETSI TS 102 990 V1.1.1 (2012-11)
5 Service requirements
5.1 General
[5.1.1] The CDN interconnection shall enable controlled distribution of content between two CDNs.
[5.1.2] The CDN interconnection shall support enforcement of the Consumer access control policy
defined by the Content Provider. In other words, the CDN interconnection solution shall ensure
that any delivery request is honoured, or rejected, in accordance with the access control policy
defined by the Content Provider. The Content Provider access control policy may depend, in
particular, on the content item, on the Consumer, on the Consumer location and on the request
time.
5.2 Service Types
[5.2.1] The CDN interconnection solution shall support content distributions services required for file-
based content (used e.g. for CoD) and stream-based content (used e.g. for Broadcast).
[5.2.2] The CDN interconnection solution shall support delivery format adaptation in the downstream
CDNs.
NOTE: Delivery format adaptation includes, but is not limited to, conversion to adaptive streaming, the transport
format conversion, code type conversion, content encapsulation conversion.
6 Technical requirements
6.1 General
[6.1.1] The CDN interconnection solution shall be able to distribute content from an Upstream CDN to a
Downstream CDN.
[6.1.2] The CDN interconnection solution shall be able to distribute content from an Upstream CDN to
multiple Downstream CDNs.
[6.1.3] The CDN interconnection solution shall enable an Upstream CDN to push content to a
Downstream CDN.
[6.1.4] The CDN interconnection solution shall enable a Downstream CDN to pull content from an
Upstream CDN.
[6.1.5] The CDN interconnection solution shall enable the Downstream CDN to dynamically discover the
content location information in order to pull content from an Upstream CDN in line with the
content policy requirements by the Content Provider.
[6.1.6] The CDN interconnection solution shall enable an Upstream CDN to delete content from a
Downstream CDN, but only for content that was distributed by the Upstream CDN to the
Downstream CDN.
[6.1.7] The CDN interconnection solution shall support distribution and delivery of content transparently
from its format, e.g. codec.
NOTE: This does not exclude the possibility that content is transcoded in one of the CDNs, see clause 6.3.
[6.1.8] The CDN interconnection solution shall be independent of the hardware or software of the content
consumer.
[6.1.9] The CDN interconnection solution shall be independent of the CDN technologies deployed by the
Upstream CDN and the Downstream CDN.
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12 ETSI TS 102 990 V1.1.1 (2012-11)
[6.1.10] The CDN interconnection solution shall provide support for delivery format adaptation by the
Downstream CDN according to the UE's capability and conforming to content policy and rights.
[6.1.11] The CDN interconnection solution shall not implicate dependencies between the delivery
mechanisms used by Upstream CDN and the Downstream CDN.
[6.1.12] The CDN interconnection solution shall support that one CDN selects its Downstream CDN
independently.
[6.1.13] The CDN interconnection solution may support an arrangement where the Upstream CDN Service
Provider agrees with a Downstream CDN Service Provider to use a specific CDN further
downstream.
6.2 CDN interconnection interfacing between Upstream CDN
Provider and Downstream CDN Provider
[6.2.1] The CDN interconnection solution shall have one or more technical interfaces for content
distribution that enable streaming distribution of live and stored content.
NOTE 1: Examples of candidate interface for streaming content distribution is RTP/RTCP and HTTP.
[6.2.2] The CDN interconnection solution should have one or more technical interfaces for request routing
and content distribution of stream-based unicast content from Upstream CDN to Downstream
CDN that enable the Downstream CDN to deliver the stream-based content (obtained from the
CDN interconnection) through multicast to the Consumer.
NOTE 2: Generally, multicast does not support reporting on connected users. An Upstream CDN could use
client/player statistics instead.
[6.2.3] For scenarios where the streaming content is pulled by the Downstream CDN in case of cache
miss, the CDN interconnection solution should support a technical interface allowing the
Downstream CDN to control the rate at which the streaming content is distributed to the
Downstream CDN.
[6.2.4] The CDN interconnection solution shall have one or more technical interfaces for content
distribution that enable file transfer of stored content.
NOTE 3: Examples of interfaces for file transfer are FTP and HTTP.
[6.2.5] The CDN interconnection solution shall support transfer of segmented content between CDNs.
The following types of segmented content shall be supported:
• Content composed of multiple files.
• Content composed of multiple streams.
• Content composed of one or more files and one or more streams.
NOTE 4: An example of content composed of multiple files is HTTP adaptive streaming. An example of content
composed of multiple streams is tiled video, i.e. a high-resolution video composed of spatially separate
lower-resolution video streams. Another example of content composed of multiple streams is scalable
video coding (SVC).
[6.2.6] The CDN interconnection solution shall support transfer of partial sets of individual content
segments between CDNs.
[6.2.7] The CDN interconnection solution should support efficient delivery of segmented content when
different content segments are delivered from different CDNs.
[6.2.8] The CDN interconnection solution shall allow interfaces between Upstream CDN and
Downstream CDN to be realised over a managed network, e.g. a leased lined or a managed IP
network.
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[6.2.9] The CDN interconnection solution shall allow interfaces between Upstream CDN and
Downstream CDN to be realised over an unmanaged network, e.g. the internet.
[6.2.10] The CDN interconnection solution should allow one or more control-plane interfaces between
Upstream CDN and Downstream CDN, for establishing agreement over desired delivery attributes
among associated CDNs.
NOTE 5: Examples of desired delivery attributes can be, but not limited to, reach ability/route characteristics,
delivery related service level agreements, QoS attributes, performance thresholds, supported content
lookup methods, content type and related attributes, supported failover abilities.
6.3 Transcoding
[6.3.1] The CDN interconnection solution shall support distribution of content that is transcoded or
processed by the Upstream CDN.
[6.3.2] The CDN interconnection solution shall support distribution of content that is transcoded or
processed by the Downstream CDN.
NOTE 1: Transcoding or processing of content may be useful to make content better suited for distribution over
access networks with a small bandwidth (e.g. a mobile network), or with an unknown and widely varying
available bandwidth (e.g. the internet).
NOTE 2: The transcoding or processing of content itself is not a requirement of the present document.
6.4 CDN-I Security Requirements
6.4.1 Integrity Requirements
[6.4.1.1] The CDN interconnection solution shall enable the Upstream CDN to validate the integrity of the
content.
[6.4.1.2] The CDN interconnection solution shall enable the Downstream CDN to validate the integrity of
the content.
[6.4.1.3] The CDN interconnection solution shall assign unique and non-forgeable identities to all CDN
content that are verifiable for users. The uniqueness shall be guaranteed for a period of time of
more than one year.
6.4.2 Authenticity Requirements
[6.4.2.1] The CDN interconnection solution shall enable the Upstream CDN verify the authenticity of the
source (origin) of content.
[6.4.2.2] The CDN interconnection solution shall enable the Downstream CDN verify the authenticity of the
source (origin) of content.
[6.4.2.3] The CDN interconnection solution shall enable the Upstream CDN to authenticate communication
from the Downstream CDN and vice versa.
6.4.3 Authorization Requirements
[6.4.3.1] The CDN interconnection solution shall enable access to requested content only to authorized
users, subscribers and devices.
[6.4.3.2] The CDN interconnection solution shall deny access to requested content by unauthorized users,
subscribers and devices.
[6.4.3.3] The CDN interconnection content protection functions shall provide a means for protecting time-
restricted content usage.
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14 ETSI TS 102 990 V1.1.1 (2012-11)
[6.4.3.4] The CDN interconnection solution shall allow the Content Provider to explicitly authorize
individual Consumer content request before it is honoured. In particular, this mechanism shall
ensure that a Consumer cannot by-pass the Content Provider authorization even when the
Consumer is aware of a content locator or identifier (e.g. URI) that has been used by that consumer
before or by another Consumer (anti-deep linking). URL signing is a candidate mechanism to
support this anti-deep linking requirement.
6.4.4 Confidentiality Requirements
[6.4.4.1] The CDN interconnection solution shall provide content confidentiality protection within
regulatory constraints.
6.4.5 Denial of Service Protection Requirements
[6.4.5.1] The CDN interconnection solution shall have measures to detect Denial of Service (DoS) attacks
posed upon the CDN interconnection solution. It should protect against Denial of Service (DoS)
attacks to ensure fulfilment of the requirements of the Content Provider regarding timeliness and
quality.
6.4.6 Digital rights management (DRM)
[6.4.6.1] The CDN interconnection solution shall support transparency to the DRM solution used by the
Content Provider.
[6.4.6.2] The CDN interconnection solution should be used for distribution of DRM keys.
[6.4.6.3] DRM solutions supported by the CDN interconnection solution should include the key
management, the delivery, and encryption and decryption operations of keys and content, and the
corresponding interfaces.
[6.4.6.4] The CDN interconnection solution should have content files and - streams encrypted throughout
all CDN stages: ingestion, storage, distribution and delivery.
NOTE 1: The two above requirements do not directly impact the CDN, but they may impact the DRM solution
used over the CDN.
[6.4.4.5] The CDN interconnection solution should enable Content-Provider controlled-changing of the
content encryption by the Upstream CDN and/or Downstream CDN.
NOTE 2: There exist cryptographic systems that enable re-encryption of content without decrypting it. In such
systems, the Content Provider would have to encrypt a piece of content only once, whereas each
Consumer could receive a tailor-encrypted version of the content. As the Content Provider is in control of
the keys, it can trust that the integrity and security of the content is maintained.
6.5 Retrieving content identification
[6.5.1] The CDN interconnection solution shall be compatible with the Consumer retrieving the content
identification from the Content Provider.
NOTE: The mechanism how the Consumer retrieves the content location is out of scope of the present document.
[6.5.2] The CDN interconnection solution shall be able to support and resolve TV URI's for the
identification of television channels, as specified in TS 184 009 [2].
6.6 Resolving content location
[6.6.1] The CDN interconnection solution shall enable a Consumer to be redirected by the Content
Provider to the Upstream CDN.
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15 ETSI TS 102 990 V1.1.1 (2012-11)
NOTE: Once the content is ingested into the CDN, there may be no need any more for this redirection. Typically
the web site of a Content Provider has an object included that directly relates to the Upstream CDN.
[6.6.2] The CDN interconnection solution shall enable a Consumer to be redirected by the Content
Provider to the Downstream CDN.
[6.6.3] The CDN interconnection solution shall allow an Upstream CDN Provider to select a Downstream
CDN Provider to handle the request. When the selected CDN Provider is not the Delivering CDN,
the CDN interconnection solution shall allow the selected CDN, in turn to select a Downstream
CDN Provider, and so on until the selected CDN is the Delivering CDN.
[6.6.4] The CDN interconnection solution shall not restrict the set of criteria that can be taken into
account by the Upstream CDN Provider to select a Downstream CDN Provider. This shall include,
and not be restricted to, the content item, the content type, the Consumer, the Consumer geo-
location, time of day, tariffs of Downstream CDN, Downstream CDN performance, and
administrative policy.
[6.6.5] The CDN interconnection solution shall support CDN Provider loop prevention (e.g. to avoid a
scenario where CDN Provider 1 selects CDN Provider 2 that selects CDN Provider 3 that selects
CDN Provider 1).
[6.6.6] The CDN interconnection solution shall enable a Consumer to be redirected by the Upstream CDN
to the Delivering CDN Provider. This applies both in the absence of Transiting CDN Provider and
in the presence of one or more CDN Transiting Provider(s).
[6.6.7] The CDN interconnection solution shall support an optional mechanism to limit the number of
transiting CDNs involved in the request redirection.
[6.6.8] The CDN interconnection solution shall support an optional crank-back mechanism in case the
Downstream CDN Provider selected by the Upstream CDN Provider cannot handle the redirection.
This allows the Upstream CDN to select another Downstream CDN (or itself) to honour handle the
request.
[6.6.9] The CDN interconnection solution shall be compatible with the Upstream CDN Provider
retrieving the content location from the Downstream CDN Provider.
6.7 Reporting
[6.7.1] The CDN interconnection solution shall enable the Downstream CDN Provider to provide status
report on identified content to the Upstream CDN Provider.
[6.7.2] The CDN interconnection solution shall enable the Upstream CDN Provider to retrieve status
reports on identified content from the Downstream CDN Provider.
NOTE 1: Examples of status of identified content are "receiving", "preparing", "ready for delivery", "Ingesting",
"unavailable", "deleted" and "unknown".
[6.7.3] The CDN interconnection solution shall enable the Downstream CDN Provider to provide detailed
transaction logs on identified content to the Upstream CDN Provider for deliveries performed on
behalf of that Upstream CDN Provider.
[6.7.4] The CDN interconnection solution shall enable the Upstream CDN Provider to retrieve detailed
transaction logs on identified content from the Downstream CDN Provider for deliveries
performed on behalf of that Upstream CDN Provider.
NOTE 2: Examples of transaction logs information, for each delivery, include content identifier, start time, finish
time, and delivery quality indicators (resolution, bandwidth, loss, etc.).
ETSI
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