Network Working Group K. Leung, Ed.
Internet-Draft Cisco
Intended status: Informational Y. Lee, Ed.
Expires: June 9, 2012 Comcast
December 7, 2011
Content Distribution Network Interconnection (CDNI) Requirements
draft-ietf-cdni-requirements-02
Abstract
Content Delivery Networks (CDNs) are frequently used for large-scale
content delivery. As a result, existing CDN providers are scaling up
their infrastructure and many Network Service Providers (NSPs) are
deploying their own CDNs. There is a requirement for interconnecting
standalone CDNs so that their collective CDN footprint can be
leveraged for the end-to-end delivery of content from Content Service
Providers (CSPs) to end users. The Content Distribution Network
Interconnection (CDNI) working group has been chartered to develop an
interoperable and scalable solution for such CDN interconnection.
The goal of the present document is to outline the requirements for
the solution and interfaces to be specified by the CDNI working
group. This draft is a work in progress and requirements may be
added, modified, or removed by the working group.
Requirements Language
The key words "High Priority", "Medium Priority" and "Low Priority"
in this document are to be interpreted in the following way:
o "High Priority" indicates requirements that are to be supported by
the CDNI interfaces. A requirement is stated as "High Priority"
when it is established by the working group that it can be met
without compromising the targeted schedule for WG deliverables, or
when it is established that specifying a solution without meeting
this requirement would not make sense and would justify re-
adjusting the WG schedule, or both. This is tagged as "[HIGH]".
o "Medium Priority" indicates requirements that are to be supported
by the CDNI interfaces unless the WG realizes at a later stage
that attempting to meet this requirement would compromise the
overall WG schedule (for example it would involve complexities
that would result in significantly delaying the deliverables).
This is tagged as "[MED]".
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o "Low Priority" indicates requirements that are to be supported by
the CDNI interfaces provided that dedicating WG resources to this
work does not prevent addressing "High Priority" and "Medium
Priority" requirements and that attempting to meet this
requirement would not compromise the overall WG schedule. This is
tagged as "[LOW]".
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 9, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. CDNI Model and CDNI Interfaces . . . . . . . . . . . . . . . . 4
3. Generic CDNI Requirements . . . . . . . . . . . . . . . . . . 6
4. CDNI Control Interface Requirements . . . . . . . . . . . . . 7
5. CDNI Request Routing Interface Requirements . . . . . . . . . 10
6. CDNI Metadata Distribution Interface Requirements . . . . . . 13
7. CDNI Logging Interface Requirements . . . . . . . . . . . . . 16
8. CDNI Security Requirements . . . . . . . . . . . . . . . . . . 18
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
10. Security Considerations . . . . . . . . . . . . . . . . . . . 19
11. Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
13.1. Normative References . . . . . . . . . . . . . . . . . . . 20
13.2. Informative References . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
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1. Introduction
The volume of video and multimedia content delivered over the
Internet is rapidly increasing and expected to continue doing so in
the future. In the face of this growth, Content Delivery Networks
(CDNs) provide numerous benefits: reduced delivery cost for cacheable
content, improved quality of experience for end users, and increased
robustness of delivery. For these reasons CDNs are frequently used
for large-scale content delivery. As a result, existing CDN
providers are scaling up their infrastructure and many Network
Service Providers (NSPs) are deploying their own CDNs. It is
generally desirable that a given content item can be delivered to an
End User regardless of that End User's location or attachment
network. However, the footprint of a given CDN in charge of
delivering a given content may not expand close enough to the End
User's current location or attachment network to realize the cost
benefit and user experience that a more distributed CDN would
provide. This creates a requirement for interconnecting standalone
CDNs so that their collective CDN footprint can be leveraged for the
end-to-end delivery of content from Content Service Providers (CSPs)
to End Users. The Content Distribution Network Interconnection
(CDNI) working group has been chartered to develop an interoperable
and scalable solution for such CDN interconnection.
[I-D.ietf-cdni-problem-statement] outlines the problem area that the
CDNI working group is chartered to address.
[I-D.ietf-cdni-use-cases] discusses the use cases for CDN
Interconnection. [I-D.davie-cdni-framework] discusses the technology
framework for the CDNI solution and interfaces.
The goal of the present document is to document the requirements for
the CDNI solution and interfaces. In order to meet the timelines
defined in the working group charter, the present document
categorizes the CDNI requirements as "High Priority", "Medium
Priority", and "Low Priority".
1.1. Terminology
This document uses the terminology defined in section 1.1 of
[I-D.davie-cdni-framework].
2. CDNI Model and CDNI Interfaces
For convenience Figure 1 from [I-D.davie-cdni-framework] illustrating
the CDNI problem area and the CDNI protocols is replicated below.
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--------
/ \
| CSP |
\ /
--------
*
*
* /\
* / \
---------------------- |CDNI| ----------------------
/ Upstream CDN \ | | / Downstream CDN \
| +-------------+ | Control Interface| +-------------+ |
|******* Control |<======|====|========>| Control *******|
|* +------*----*-+ | | | | +-*----*------+ *|
|* * * | | | | * * *|
|* +------*------+ | Logging Interface| +------*------+ *|
|* ***** Logging |<======|====|========>| Logging ***** *|
|* * +-*-----------+ | | | | +-----------*-+ * *|
|* * * * | Request Routing | * * * *|
.....*...+-*---------*-+ | Interface | +-*---------*-+...*.*...
. |* * *** Req-Routing |<======|====|========>| Req-Routing *** * *| .
. |* * * +-------------+.| | | | +-------------+ * * *| .
. |* * * . CDNI Metadata | * * *| .
. |* * * +-------------+ |. Interface | +-------------+ * * *| .
. |* * * | Distribution|<==.===|====|========>| Distribution| * * *| .
. |* * * | | | . \ / | | | * * *| .
. |* * * |+---------+ | | . \/ | | +---------+| * * *| .
. |* * ***| +---------+| | ....Request......+---------+ |*** * *| .
. |* *****+-|Surrogate|************************|Surrogate|-+***** *| .
. |******* +---------+| | Acquisition | |+----------+ *******| .
. | +-------------+ | | +-------*-----+ | .
. \ / \ * / .
. ---------------------- ---------*------------ .
. * .
. * Delivery .
. * .
. +--*---+ .
...............Request.............................| User |..Request..
| Agent|
+------+
<==> interfaces inside the scope of CDNI
**** interfaces outside the scope of CDNI
.... interfaces outside the scope of CDNI
Figure 1: CDNI Model and CDNI Interfaces
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3. Generic CDNI Requirements
This section identifies generic requirements independent of the
individual CDNI interfaces. Some of those are expected to affect
multiple or all interfaces.
GEN-1 [MED] Wherever possible, the CDNI interfaces should reuse or
leverage existing IETF protocols.
GEN-2 [HIGH] The CDNI solution shall not require a change, or an
upgrade, to the User Agent to benefit from content delivery
through interconnected CDNs.
GEN-3 [HIGH] The CDNI solution shall not require a change, or an
upgrade, to the Content Service Provider to benefit from
content delivery through interconnected CDNs.
GEN-4 [HIGH] The CDNI solution shall not require intra-CDN
information to be exposed to other CDNs for effective and
efficient delivery of the content. Examples of intra-CDN
information include surrogate topology, surrogate status,
cached content, etc.
GEN-5 [HIGH] The CDNI solution shall support delivery to the user
agent based on HTTP [RFC2616]. (Note that while delivery and
acquisition "data plane" protocols are out of the CDNI
solution scope, the CDNI solution "control plane" protocols
are expected to participate in enabling, selecting or
facilitating operations of such acquisition and delivery
protocols. Hence it is useful to state requirements on the
CDNI solution in terms of which acquisition and delivery
protocols).
GEN-6 [HIGH] The CDNI solution shall support acquisition across
CDNs based on HTTP [RFC2616].
GEN-7 [LOW] The CDNI solution may support delivery to the user
agent based on protocols other than HTTP.
GEN-8 [LOW] The CDNI solution may support acquisition across CDNs
based on protocols other than HTTP.
GEN-9 [MED] The CDNI solution should support cascaded CDN
redirection (CDN1 redirects to CDN2 that redirects to CDN3)
to an arbitrary number of levels beyond the first level.
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GEN-10 [MED] The CDNI solution should support an arbitrary topology
of interconnected CDNs (i.e. the CDN topology cannot be
restricted to a tree, a loop-free topology, etc.).
GEN-11 [HIGH] The CDNI solution shall prevent looping of any CDNI
information exchange.
GEN-12 [HIGH] When making use of third party reference, the CDNI
solution shall consider the potential issues associated with
the use of various format of third-party references (e.g.
NAT or IPv4/IPv6 translation potentially breaking third-party
references based on an IP addresses such as URI containing
IPv4 or IPv6 address litterals, split DNS situations
potentially breaking third-party references based on DNS
fully qualified domain names) and wherever possible avoid,
minimize or mitigate the associated risks based on the
specifics of the environments where the reference is used
(e.g. likely or unlikely presence of NAT in the path). In
particular, this applies to situations where the CDNI
solution needs to construct and convey uniform resource
identifiers for directing/redirecting a content request, as
well as to situations where the CDNI solution needs to pass
on a third party reference (e.g. to identify a User Agent) in
order to allow another entity to make a more informed
decision (e.g. make a more informed request routing decision
by attempting to derive location information from the third
party reference).
GEN-13
GEN-14 [HIGH] The CDNI solution shall support HTTP Adaptive Bit Rate
(ABR) content.
4. CDNI Control Interface Requirements
The primary purpose of the CDNI Control interface is to initiate the
interconnection across CDNs, bootstrap the other CDNI interfaces and
trigger actions into the Downstream CDN by the Upstream CDN (such as
delete object from caches or trigger pre-positioned content
acquisition). We observe that while the CDNI Control interface is
currently discussed as a single "protocol", further analysis will
determine whether the corresponding requirements are to be realized
over a single interface and protocol, or over multiple interfaces and
protocols.
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CNTL-1 [HIGH] The CDNI Control interface shall allow the Upstream
CDN to request that the Downstream CDN (and, if cascaded
CDNs are supported by the solution, that the potential
cascaded Downstream CDNs) perform the following actions on
an object or object set:
* Mark an object or set of objects and/or its CDNI
metadata as "stale" and revalidate them before they are
delivered again
* Delete an object or set of objects and/or its CDNI
metadata from the CDN surrogates and any storage. Only
the object(s) and CDNI metadata that pertain to the
requesting Upstream CDN are allowed to be purged.
CNTL-2 [HIGH] The CDNI Control interface shall allow the Downstream
CDN to report on the completion of these actions (by itself,
and if cascaded CDNs are supported by the solution, by
potential cascaded Downstream CDNs), in a manner appropriate
for the action (e.g. synchronously or asynchronously). The
confirmation receipt should include a success or failure
indication. The failure indication is used if the
Downstream CDN cannot delete the content in its storage.
CNTL-3 [HIGH] The CDNI Control interface shall support initiation
and control by the Upstream CDN of pre-positioned CDNI
metadata acquisition by the Downstream CDN.
CNTL-4 [MED] The CDNI Control interface should support initiation
and control by the Upstream CDN of pre-positioned content
acquisition by the Downstream CDN.
CNTL-5 [LOW] The CDNI Control interface may allow a CDN to
establish, update and terminate a CDN interconnection with
another CDN whereby one CDN can act as a Downstream CDN for
the other CDN (that acts as an Upstream CDN).
CNTL-6 [LOW] The CDNI Control interface may allow control of the
CDNI interconnection between any two CDNs independently for
each direction (i.e. For the direction where CDN1 is the
Upstream CDN and CDN2 is the Downstream CDN, and for the
direction where CDN2 is the Upstream CDN and CDN1 is the
Downstream CDN).
CNTL-7 [LOW] The CDNI Control interface may allow bootstrapping of
the Request-Routing interface. For example, this can
potentially include:
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* negotiation of the Request-Routing method (e.g. DNS vs
HTTP, if more than one method is specified)
* discovery of the Request-Routing protocol endpoints
* information necessary to establish secure communication
between the Request-Routing protocol endpoints.
CNTL-8 [LOW] The CDNI Control interface may allow bootstrapping of
the CDNI Metadata interface. This information could, for
example, include:
* discovery of the CDNI Metadata signaling protocol
endpoints
* information necessary to establish secure communication
between the CDNI Metadata signaling protocol endpoints.
CNTL-9 [LOW] The CDNI Control interface may allow bootstrapping of
the Content Acquisition interface. This could, for example,
include exchange and negotiation of the Content Acquisition
protocols to be used across the CDNs (e.g. HTTP, HTTPS,
FTP, ATIS C2).
CNTL-10 [LOW] The CDNI Control interface may allow exchange and
negotiation of delivery authorization mechanisms to be
supported across the CDNs (e.g. URI signature based
validation).
CNTL-11 [LOW] The CDNI Control interface may allow bootstrapping of
the CDNI Logging interface. This information could, for
example, include:
* discovery of the Logging protocol endpoints
* information necessary to establish secure communication
between the Logging protocol endpoints
* negotiation/definition of the log file format and set of
fields to be exported through the Logging protocol, with
some granularity (e.g. On a per content type basis).
* negotiation/definition of parameters related to
transaction Logs export (e.g., export protocol, file
compression, export frequency, directory).
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5. CDNI Request Routing Interface Requirements
The main function of the Request Routing interface is to allow the
Request-Routing systems in interconnected CDNs to communicate to
facilitate redirection of the request across CDNs.
REQ-1 [HIGH] The CDNI Request-Routing interface shall allow the
Downstream CDN to communicate to the Upstream CDN coarse
information about the Downstream CDN ability and/or
willingness to handle requests from the Upstream CDN. For
example, this could potentially include a binary signal
("Downstream CDN ready/not-ready to take additional requests
from Upstream CDN") to be used in case of excessive load or
failure condition in the Downstream CDN.
REQ-2 [MED] The CDNI Request-Routing interface should allow the
Downstream CDN to communicate to the Upstream CDN aggregate
information to facilitate CDN selection during request
routing, such as Downstream CDN capabilities, resources and
affinities (i.e. Preferences or cost). This information
could, for example, include:
* supported content types and delivery protocols
* footprint (e.g. layer-3 coverage)
* a set of metrics/attributes (e.g. Streaming bandwidth,
storage resources, distribution and delivery priority)
* a set of affinities (e.g. Preferences, indication of
distribution/delivery fees)
* information to facilitate request redirection (e.g.
Reachability information of Downstream CDN Request
Routing system).
[Note: Some of this information - such as supported content
types and delivery protocols- may also potentially be taken
into account by the distribution system in the Upstream CDN
for pre-positioning of content and/or metadata in the
Downstream CDN in case of pre-positioned content acquisition
and/or pre-positioned CDNI metadata acquisition.]
REQ-3 [MED] In the case of cascaded redirection, the CDNI Request-
Routing interface shall allow the Downstream CDN to also
include in the information communicated to the Upstream CDN,
information on the capabilities, resources and affinities of
CDNs to which the Downstream CDN may (in turn) redirect
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requests received by the Upstream CDN. In that case, the
CDNI Request-Routing interface shall prevent looping of such
information exchange.
REQ-4 [LOW] The CDNI Request-Routing interface may allow the
Downstream CDN to communicate to the Upstream CDN aggregate
information on CDNI administrative limits and policy. This
information can be taken into account by the Upstream CDN
Request Routing system in its CDN Selection decisions. This
information could, for example, include:
* maximum number of requests redirected by the Upstream CDN
to be served simultaneously by the Downstream CDN
* maximum aggregate volume of content (e.g. in Terabytes)
to be delivered by the Downstream CDN over a time period.
REQ-5 [HIGH] The CDNI Request-Routing architecture and interface
shall support efficient request-routing for small objects.
This may, for example, call for a mode of operation (e.g.
DNS-based request routing) where freshness and accuracy of
CDN/Surrogate selection can be traded-off against reduced
request-routing load (e.g. Via lighter-weight queries and
caching of request-routing decisions).
REQ-6 [HIGH] The CDNI Request-Routing architecture and interface
shall support efficient request-routing for large objects.
This may, for example, call for a mode of operation (e.g.
HTTP-based request routing) where freshness and accuracy of
CDN/Surrogate selection justifies a per-request decision and
a per-request CDNI Request-Routing protocol call.
REQ-7 [HIGH] The CDNI Request-Routing architecture shall support
recursive CDNI request routing.
REQ-8 [HIGH] The CDNI Request-Routing architecture shall support
iterative CDNI request routing.
REQ-9 [MED] In case of detection of a request redirection loop, the
CDNI Request-Routing loop prevention mechanism should allow
routing of the request by avoiding the loop (as opposed to
the request loop being simply interrupted without routing the
request).
REQ-10 [MED] The CDNI Request-Routing protocol should support a
mechanism allowing enforcment of a limit on the number of
successive CDN redirections for a given request.
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REQ-11 [LOW] The CDNI Request-Routing protocol may support a
mechanism allowing an Upstream CDN to avoid redirecting a
request to a Downstream CDN if that is likely to result in
the total redirection time exceeding some limit.
REQ-12 [HIGH] The CDNI Request-Routing protocol shall allow the
Upstream CDN to include, in the query to the Downstream CDN,
the necessary information to allow the Downstream CDN to
process the redirection query. This could, for example,
include:
* information from which the location of the user-agent
that originated the request can be inferred (e.g. User
Agent fully qualified domain name in case of HTTP-based
Request Routing, DNS Proxy fully qualified domain name in
case of DNS-based Request Routing)
* requested resource information (e.g. Resource URI in
case of HTTP-based Request Routing, Resource hostname in
case of DNS-based Request Routing)
* additional available request information (e.g. request
headers in case of HTTP-based Request Routing).
REQ-13 [LOW] The CDNI Request-Routing protocol may also allow the
Upstream CDN to convey information pointing to CDNI metadata
applicable (individually or through inheritance) to the
requested content. For illustration, the CDNI metadata
pointed to could potentially include metadata that is
applicable to any content, metadata that is applicable to a
content collection (to which the requested content belongs)
and/or metadata that is applicable individually to the
requested content.
REQ-14 [HIGH] The CDNI Request-Routing interface shall allow the
Downstream CDN to include the following information in the
response to the Upstream CDN:
* status code, in particular indicating acceptance or
rejection of request (e.g. Because the Downstream CDN is
unwilling or unable to serve the request). In case of
rejection, an error code is also to be provided, which
allows the Upstream CDN to react appropriately (e.g.
Select another Downstream CDN, or serve the request
itself)
* redirection information (e.g. Resource URI in case of
HTTP-based Request Routing, equivalent of a DNS record in
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case of DNS-based Request Routing).
6. CDNI Metadata Distribution Interface Requirements
The primary function of the CDNI Metadata Distribution interface is
to allow the Distribution system in interconnected CDNs to
communicate to ensure Content Distribution Metadata with inter-CDN
scope can be exchanged across CDNs. We observe that while the CDNI
Metadata Distribution protocol is currently discussed as a single
"protocol", further analysis will determine whether the corresponding
requirements are to be realized over a single interface and protocol,
or over multiple interfaces and protocols. For example, a subset of
the CDNI metadata might be conveyed in-band along with the actual
content acquisition across CDNs (e.g. content MD5 in HTTP header)
while another subset might require an out-of-band interface &
protocol (e.g. geo-blocking information).
META-1 [HIGH] The CDNI Metadata Distribution interface shall allow
the Upstream CDN to provide the Downstream CDN with content
distribution metadata of inter-CDN scope.
META-2 [HIGH] The CDNI Metadata Distribution interface shall
support exchange of CDNI metadata for both the dynamic
content acquisition model and the pre-positioning content
acquisition model.
META-3 [HIGH] The CDNI Metadata Distribution interface shall
support a mode where no, or a subset of, the Metadata is
initially communicated to the Downstream CDN along with
information about how/where to acquire the rest of the CDNI
Metadata (i.e. Dynamic CDNI metadata acquisition).
META-4 [MED] The CDNI Metadata Distribution interface should
support a mode where all the relevant Metadata is initially
communicated to the Downstream CDN (i.e. Pre-positioned
CDNI metadata acquisition).
META-5 [HIGH] Whether in the pre-positioned content acquisition
model or in the dynamic content acquisition model, the CDNI
Metadata Distribution interface shall provide the necessary
information to allow the Downstream CDN to acquire the
content from an upstream source (e.g. Acquisition protocol
and Uniform Resource Identifier in Upstream CDN- or rules to
construct this URI).
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META-6 [HIGH] The CDNI metadata shall allow signaling of one or
more upstream sources, where each upstream source can be in
the Upstream CDN, in another CDN, the CSP origin server or
any arbitrary source designated by the Upstream CDN. Note
that some upstream sources (e.g. the content origin server)
may or may not be willing to serve the content to the
Downstream CDN, if this policy is known to the Upstream CDN
then it may omit those sources when exchanging CDNI
metadata.
META-7 [HIGH] The CDNI Metadata Distribution interface shall allow
the Upstream CDN to request addition and modification of
CDNI Metadata into the Downstream CDN.
META-8 [HIGH] The CDNI Metadata Distribution interface shall allow
removal of obsolete CDNI Metadata from the Downstream CDN
(this could, for example, be achieved via an explicit
removal request from the Upstream CDN or via expiration of a
Time-To-Live associated to the Metadata).
META-9 [HIGH] The CDNI Metadata Distribution interface shall allow
association of CDNI Metadata at the granularity of
individual object. This is necessary to achieve fine-grain
Metadata distribution at the level of an individual object
when necessary.
META-10 [HIGH] The CDNI Metadata Distribution interface shall allow
association of CDNI Metadata at the granularity of an object
set. This is necessary to achieve scalable distribution of
metadata when a large number of objects share the same
distribution policy.
META-11 [HIGH] The CDNI Metadata Distribution interface shall
support multiple levels of inheritance with precedence to
more specific metadata. For example, the CDNI Metadata
Distribution protocol may support metadata that is
applicable to any content, metadata that is applicable to a
content collection and metadata that is applicable to an
individual content where content level metadata overrides
content collection metadata that overrides metadata for any
content.
META-12 [HIGH] The CDNI Metadata Distribution interface shall ensure
that conflicting metadata with overlapping scope are
prevented or deterministically handled.
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META-13 [HIGH] The CDNI Metadata Distribution interface shall
provide indication by the Downstream CDN to the Upstream CDN
of whether the CDNI metadata (and corresponding future
request redirections) is accepted or rejected. When
rejected, the CDNI Metadata Distribution protocol Must allow
the Downstream CDN to provide information about the cause of
the rejection.
META-14 [HIGH] The CDNI Metadata Distribution interface shall allow
signaling of content distribution control policies. For
example, this could potentially include:
* geo-blocking information (i.e. Information defining
geographical areas where the content is to be made
available or blocked)
* availability windows (i.e. Information defining time
windows during which the content is to be made available
or blocked; expiration time may also be included to
remove content)
* delegation whitelist/blacklist (i.e. Information
defining which Downstream CDNs the content may/may not
be delivered through)
META-15 [HIGH] The CDNI Metadata interface shall be able to exchange
a set of well-accepted metadata elements with specified
semantics (e.g. start of time window, end of time window).
META-16 [HIGH] The CDNI Metadata interface shall allow exchange of
opaque metadata element, whose semantic is not defined in
CDNI but established by private CDN agreement.
META-17 [HIGH] The CDNI Metadata Distribution interface shall allow
signaling of authorization checks and validation that are to
be performed by the surrogate before delivery. For example,
this could potentially include:
* need to validate URI signed information (e.g. Expiry
time, Client IP address).
META-18 [LOW] The CDNI Metadata Distribution interface may allow
signaling of CDNI-relevant surrogate cache behavior
parameters. For example, this could potentially include:
* control of whether the query string of HTTP URI is to be
ignored by surrogate cache
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* content revalidation parameters (e.g. TTL)
7. CDNI Logging Interface Requirements
This section identifies the requirements related to the CDNI Logging
interface. We observe that while the CDNI Logging interface is
currently discussed as a single "protocol", further analysis will
determine whether the corresponding requirements are to be realized
over a single interface and protocol, or over multiple interfaces and
protocols.
LOG-1 [HIGH] The CDNI logging architecture and interface shall
ensure reliable logging of CDNI events.
LOG-2 [HIGH] The CDNI Logging interface shall provide logging of
deliveries and incomplete deliveries to User Agents performed
by the Downstream CDN as a result of request redirection by
the Upstream CDN.
LOG-3 [MED] In the case of cascaded CDNs, the CDNI Logging
interface shall allow the Downstream CDN to report to the
Upstream CDN logging for deliveries and incomplete deliveries
performed by the Downstream CDN itself as well as logging for
deliveries and incomplete deliveries performed by cascaded
CDNs on behalf of the Downstream CDN.
LOG-4 [HIGH] The CDNI Logging interface shall provide logging of
distribution performed by the Upstream CDN as a result of
acquisition request by the Downstream CDN.
LOG-5 [HIGH] The CDNI Logging interface shall support batch/offline
exchange of logging records.
LOG-6 [MED] The CDNI Logging interface should also support
additional timing constraints for some types of logging
records (e.g. near-real time for monitoring and analytics
applications)
LOG-7 [HIGH] The CDNI Logging interface shall define a log file
format and a set of fields to be exported through the Logging
protocol, with some granularity (e.g. On a per content type
basis).
LOG-8 [HIGH] The CDNI Logging interface shall define a transport
mechanisms to exchange CDNI Logging files.
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LOG-9 [MED] The CDNI Logging interface may allow a CDN to query
another CDN for relevant current logging records (e.g. For
on-demand access to real-time logging information).
LOG-10 [LOW] The CDNI Logging interface may support aggregate/
summarized logs (e.g. total bytes delivered for a content
regardless of individual User Agents to which it was
delivered).
LOG-11 [LOW] The CDNI Logging interface shall support logging of
performance data for deliveries to User Agents performed by
the Downstream CDN as a result of request redirection by the
Upstream CDN. Performance data may include various traffic
statistics (the specific parameters are to be determined).
The CDNI Logging interface shall support the Upstream CDN to
indicate the nature and contents of the performance data to
be reported by the Downstream CDN.
LOG-12 [MED] The CDNI Logging interface shall support logging of
consumed resources (e.g. storage, bandwidth) to the Upstream
CDN for deliveries where content is stored by the Downstream
CDN for delivery to User Agents. The information logged may
include the type of storage (e.g., Origin, Intermediate,
Edge, Cache) as well as the amount of storage (e.g., total
GB, GB used, per time period, per content domain) all of
which may impact the cost of the services.
LOG-13 [MED] In the case of cascaded CDNs, the CDNI Logging
interface shall support the Downstream CDN to report consumed
resources (e.g. storage, bandwidth) to the Upstream CDN where
content is stored by the Downstream CDN itself as well as
logging for storage resources when content storage is
performed by cascaded CDNs on behalf of the Downstream CDN.
LOG-14 [HIGH] The CDNI Logging interface shall support logging of
deleted objects from the Downstream CDN to the Upstream CDN
as a result of explicit delete requests on via the CDNI
Control interface from the Upstream CDN.
LOG-15 [HIGH] The CDNI Logging interface shall support extensibility
to allow proprietary information fields to be carried. These
information fields must be agreed upon ahead of time between
the corresponding CDNs.
LOG-16 [HIGH] The CDNI Logging interface shall support the exchange
of extensible log file formats to support proprietary
information fields. These information fields must be agreed
upon ahead of time between the corresponding CDNs.
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8. CDNI Security Requirements
This section identifies the requirements related to the CDNI
security. Some of those are expected to affect multiple or all
protocols.
SEC-1 [HIGH] All the CDNI interface shall support secure operation
over unsecured IP connectivity (e.g. The Internet). This
includes authentication, confidentiality, integrity protection
as well as protection against spoofing and replay.
SEC-2 [HIGH] The CDNI solution shall provide sufficient protection
against Denial of Service attacks. This includes protection
against spoofed delivery requests sent by user agents directly
to a Downstream CDN attempting to appear as if they had been
redirected by a given Upstream CDN when they have not.
SEC-3 [MED] The CDNI solution should be able to ensure that for any
given request redirected to a Downstream CDN, the chain of CDN
Delegation (leading to that request being served by that CDN)
can be established with non-repudiation.
SEC-4 [MED] The CDNI solution should be able to ensure that the
Downstream CDN cannot spoof a transaction log attempting to
appear as if it corresponds to a request redirected by a given
Upstream CDN when that request has not been redirected by this
Upstream CDN. This ensures non-repudiation by the Upstream
CDN of transaction logs generated by the Downstream CDN for
deliveries performed by the Downstream CDN on behalf of the
Upstream CDN.
SEC-5 [LOW] The CDNI solution may provide a mechanism allowing an
Upstream CDN that has credentials to acquire content from the
CSP origin server (or another CDN), to allow establishment of
credentials authorizing the Downstream CDN to acquire the
content from the CSP origin server (or the other CDN) (e.g.
In case the content cannot be acquired from the Upstream CDN).
9. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
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10. Security Considerations
This document discusses CDNI security requirements in Section 8.
11. Authors
This document reflects the contributions from the following authors:
Francois Le Faucheur
Cisco Systems
flefauch@cisco.com
Mahesh Viveganandhan
Cisco Systems
mvittal@cisco.com
Grant Watson
BT
grant.watson@bt.com
12. Acknowledgements
This document leverages the earlier work of the IETF CDI working
group in particular as documented in [I-D.cain-request-routing-req],
[I-D.amini-cdi-distribution-reqs] and [I-D.gilletti-cdnp-aaa-reqs].
The authors would like to thank Gilles Bertrand, Christophe Caillet,
Bruce Davie, Phil Eardly, Ben Niven-Jenkins, Agustin Schapira, Emile
Stephan, Eric Burger, Susan He, Kevin Ma, and Daryl Malas for their
input. Serge Manning along with Robert Streijl, Vishwa Prasad, Percy
Tarapore, Mike Geller, and Ramki Krishnan contributed to this
document by addressing the requirements of the ATIS Cloud Services
Forum.
13. References
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13.1. Normative References
[I-D.davie-cdni-framework]
Davie, B. and L. Peterson, "Framework for CDN
Interconnection", draft-davie-cdni-framework-01 (work in
progress), October 2011.
[I-D.ietf-cdni-problem-statement]
Niven-Jenkins, B., Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", draft-ietf-cdni-problem-statement-01 (work in
progress), October 2011.
[I-D.ietf-cdni-use-cases]
Bertrand, G., Emile, S., Watson, G., Burbridge, T.,
Eardley, P., and K. Ma, "Use Cases for Content Delivery
Network Interconnection", draft-ietf-cdni-use-cases-00
(work in progress), September 2011.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
13.2. Informative References
[I-D.amini-cdi-distribution-reqs]
Amini, L., "Distribution Requirements for Content
Internetworking", draft-amini-cdi-distribution-reqs-02
(work in progress), November 2001.
[I-D.cain-request-routing-req]
Cain, B., "Request Routing Requirements for Content
Internetworking", draft-cain-request-routing-req-03 (work
in progress), November 2001.
[I-D.gilletti-cdnp-aaa-reqs]
"CDI AAA Requirements,
draft-gilletti-cdnp-aaa-reqs-01.txt", June 2001.
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Authors' Addresses
Kent Leung (editor)
Cisco Systems
170 West Tasman Drive
San Jose, CA 95134
U.S.A.
Phone: +1 408 526 5030
Email: kleung@cisco.com
Yiu Lee (editor)
Comcast
One Comcast Center
Philadelphia, PA 19103
U.S.A.
Email: yiu_lee@cable.comcast.com
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