Skip to main content

Content Distribution Network Interconnection (CDNI) Requirements
draft-ietf-cdni-requirements-06

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 7337.
Authors Kent Leung , Yiu Lee
Last updated 2013-04-09
Replaces draft-lefaucheur-cdni-requirements
RFC stream Internet Engineering Task Force (IETF)
Formats
Reviews
Additional resources Mailing list discussion
Stream WG state WG Document
Document shepherd (None)
IESG IESG state Became RFC 7337 (Informational)
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD Spencer Dawkins
Send notices to cdni-chairs@tools.ietf.org, draft-ietf-cdni-requirements@tools.ietf.org
draft-ietf-cdni-requirements-06
Network Working Group                                      K. Leung, Ed.
Internet-Draft                                                     Cisco
Intended status: Informational                               Y. Lee, Ed.
Expires: October 11, 2013                                        Comcast
                                                           April 9, 2013

    Content Distribution Network Interconnection (CDNI) Requirements
                    draft-ietf-cdni-requirements-06

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]".

Leung & Lee             Expires October 11, 2013                [Page 1]
Internet-Draft              CDNI Requirements                 April 2013

   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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 11, 2013.

Copyright Notice

   Copyright (c) 2013 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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Leung & Lee             Expires October 11, 2013                [Page 2]
Internet-Draft              CDNI Requirements                 April 2013

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/Redirection Interface Requirements  . . . 10
   6.  CDNI Request Routing/Footprint & Capabilities
       Advertisement Interface Requirements . . . . . . . . . . . . . 12
   7.  CDNI Metadata Distribution Interface Requirements  . . . . . . 14
   8.  CDNI Logging Interface Requirements  . . . . . . . . . . . . . 18
   9.  CDNI Security Requirements . . . . . . . . . . . . . . . . . . 20
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 21
   11. Security Considerations  . . . . . . . . . . . . . . . . . . . 21
   12. Authors  . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
   13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22
   14. Appendix: Requirements Mapping . . . . . . . . . . . . . . . . 22
   15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
     15.1. Normative References . . . . . . . . . . . . . . . . . . . 23
     15.2. Informative References . . . . . . . . . . . . . . . . . . 24
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24

Leung & Lee             Expires October 11, 2013                [Page 3]
Internet-Draft              CDNI Requirements                 April 2013

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.

   [RFC6707] outlines the problem area that the CDNI working group is
   chartered to address.  [RFC6770] 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.

Leung & Lee             Expires October 11, 2013                [Page 4]
Internet-Draft              CDNI Requirements                 April 2013

     --------
    /        \
    |   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

Leung & Lee             Expires October 11, 2013                [Page 5]
Internet-Draft              CDNI Requirements                 April 2013

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 depend on 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].  (The note above applies to
           this requirement too)

   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.

Leung & Lee             Expires October 11, 2013                [Page 6]
Internet-Draft              CDNI Requirements                 April 2013

   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  [HIGH] The CDNI solution shall support HTTP Adaptive
           Streaming content.

4.  CDNI Control Interface Requirements

   The primary purpose of the CDNI Control interface (CI) 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.

Leung & Lee             Expires October 11, 2013                [Page 7]
Internet-Draft              CDNI Requirements                 April 2013

   CI-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) 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.

   CI-2   [MED] The CDNI Control interface should allow for multiple
          content items identified by a Content Collection ID to be
          purged using a single Content Purge action.

   CI-3   [MED] The CDNI Control interface should 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) mark an object or set of objects and/or its
          CDNI metadata as "stale" and revalidate them before they are
          delivered again.

   CI-4   [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.

   CI-5   [MED] The CDNI Control interface should support initiation and
          control by the Upstream CDN of pre-positioned CDNI metadata
          acquisition by the Downstream CDN.

   CI-6   [MED] The CDNI Control interface should support initiation and
          control by the Upstream CDN of pre-positioned content
          acquisition by the Downstream CDN.

   CI-7   [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).

   CI-8   [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).

Leung & Lee             Expires October 11, 2013                [Page 8]
Internet-Draft              CDNI Requirements                 April 2013

   CI-9   [LOW] The CDNI Control interface may allow bootstrapping of
          the Request-Routing interface.  For example, this can
          potentially include:

          *   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.

   CI-10  [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.

   CI-11  [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).

   CI-12  [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).

Leung & Lee             Expires October 11, 2013                [Page 9]
Internet-Draft              CDNI Requirements                 April 2013

5.  CDNI Request Routing/Redirection Interface Requirements

   The main function of the CDNI request routing/ Redirection (RI)
   interface is to allow the Request-Routing systems in interconnected
   CDNs to communicate to facilitate redirection of the request across
   CDNs.

   RI-1   [HIGH] The CDNI request routing/Redirection 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).

   RI-2   [HIGH] The CDNI request routing/Redirection 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.

   RI-3   [HIGH] The CDNI request routing/Redirection interface shall
          support recursive CDNI request routing.

   RI-4   [HIGH] The CDNI request routing/Redirection interface shall
          support iterative CDNI request routing.

   RI-5   [MED] In case of detection of a request redirection loop, the
          CDNI request routing/Redirection interface's 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).

   RI-6   [MED] The CDNI request routing/Redirection interface should
          support a mechanism allowing enforcment of a limit on the
          number of successive CDN redirections for a given request.

   RI-7   [LOW] The CDNI request routing/Redirection interface 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.

   RI-8   [HIGH] The CDNI request routing/Redirection interface 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:

Leung & Lee             Expires October 11, 2013               [Page 10]
Internet-Draft              CDNI Requirements                 April 2013

          *   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).

   RI-9   [LOW] The CDNI request routing/Redirection interface 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.

   RI-10  [HIGH] The CDNI request routing/Redirection 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
              case of DNS-based Request Routing).

   RI-11  [HIGH] The CDNI request routing/Redirection interface shall
          allow for per-chunk request routing of HTTP Adaptive Streaming
          content.

   RI-12  [LOW] The CDNI request routing/Redirection interface may allow
          the Upstream CDN to use the information conveyed by the
          Downstream CDN during the Recursive Request Routing process to
          rewrite an HTTP Adaptive Streaming manifest file.

Leung & Lee             Expires October 11, 2013               [Page 11]
Internet-Draft              CDNI Requirements                 April 2013

   RI-13  [LOW] The CDNI Request-Routing interface may allow the
          Upstream CDN to re-sign the invariant portion of the chunk
          URIs embedded in the HTTP Adaptive Streaming manifest file.

   RI-14  [MED] The CDNI request routing/Redirection interface should
          allow the use of HTTP cookie to associate the chunks with the
          HTTP Adaptive Stream manifest file (which is verified by the
          URI signature) based on the Authorization Group ID (which is
          an identifier used to correlate the manifest file to the
          related chunks).

   RI-15  [MED] The CDNI request routing/Redirection interface should
          allow for an efficient method of transferring request routing
          information for multiple chunks from the Downstream CDN to the
          Upstream CDN as part of the recursive request routing process.

6.  CDNI Request Routing/Footprint & Capabilities Advertisement
    Interface Requirements

   The main function of the CDNI Request Routing Footprint &
   Capabilities Advertisement Interface (FCI) is to allow the Downstream
   CDN to advertise the information regarding its footprint and
   capabilities to the Upstream CDN.

   FCI-1  [HIGH] The CDNI request routing/Footprint & Capabilities
          advertisement 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.

   FCI-2  [MED] The CDNI request routing/Footprint & Capabilities
          advertisement 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)

Leung & Lee             Expires October 11, 2013               [Page 12]
Internet-Draft              CDNI Requirements                 April 2013

          *   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.]

   FCI-3  [MED] In the case of cascaded redirection, the CDNI request
          routing/Footprint & Capabilities advertisement interface
          should 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 requests received by
          the Upstream CDN.  In that case, the CDNI Request-Routing
          interface shall prevent looping of such information exchange.

   FCI-4  [LOW] The CDNI request routing/Footprint & Capabilities
          advertisement 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.

   FCI-5  [MED] The CDNI request routing/Footprint & Capabilities
          advertisement interface should support advertisement of the
          following types of capabilities:

          *   delivery protocol (e.g., HTTP vs. RTMP)

          *   acquisition protocol (for acquiring content from an
              Upstream CDN)

Leung & Lee             Expires October 11, 2013               [Page 13]
Internet-Draft              CDNI Requirements                 April 2013

          *   redirection mode (e.g., DNS Redirection vs. HTTP
              Redirection)

          *   capabilities related to CDNI Logging (e.g., supported
              logging mechanisms)

          *   capabilities related to CDNI Metadata (e.g., authorization
              algorithms or support for proprietary vendor metadata)

   FCI-6  [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).

7.  CDNI Metadata Distribution Interface Requirements

   The primary function of the CDNI Metadata Distribution interface (MI)
   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).

   MI-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.

   MI-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.

   MI-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).

Leung & Lee             Expires October 11, 2013               [Page 14]
Internet-Draft              CDNI Requirements                 April 2013

   MI-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).

   MI-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).

   MI-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.

   MI-7   [HIGH] The CDNI Metadata Distribution interface (possibly in
          conjunction with the CDNI Control interface) shall allow the
          Upstream CDN to request addition and modification of CDNI
          Metadata into the Downstream CDN.

   MI-8   [HIGH] The CDNI Metadata Distribution interface (possibly in
          conjunction with the CDNI Control 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).

   MI-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.

   MI-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.

Leung & Lee             Expires October 11, 2013               [Page 15]
Internet-Draft              CDNI Requirements                 April 2013

   MI-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.

   MI-12  [HIGH] The CDNI Metadata Distribution interface shall ensure
          that conflicting metadata with overlapping scope are prevented
          or deterministically handled.

   MI-13  [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)

   MI-14  [HIGH] The CDNI Metadata interface shall be able to exchange a
          set of metadata elements with specified semantics (e.g. start
          of time window, end of time window).

   MI-15  [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.

   MI-16  [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).

Leung & Lee             Expires October 11, 2013               [Page 16]
Internet-Draft              CDNI Requirements                 April 2013

   MI-17  [MED] The CDNI Metadata Distribution interface should 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

          *   enforcement of caching directives by Downstream CDN that
              are different than the ones signalled in the HTTP headers
              (e.g.  "Expires" field)

          *   rate-pacing by Downstream CDN for content delivery (e.g.
              Progressive Download)

   MI-18  [HIGH] The CDNI Metadata interface shall provide indication of
          related content (e.g.  HTTP Adaptive Bit Rate chunks) by the
          Content Collection ID (CCID) metadata.  This could be used by
          the Downstream CDN for operations on the group of content.
          For example, this could potentially include:

          *   content acquisition for the entire set of files when one
              piece of content is requested

          *   local file management and storage bundles all the files
              for the content

          *   purging the entire set of files associated with the
              content

          *   logging of the delivery of the content for the session
              when at least one file in the set was delivered

   MI-19  [MED] The CDNI Metadata Distribution interface should support
          an OPTIONAL mechanism allowing the Upstream CDN to indicate to
          the Downstream CDN which CDNI Log fields are to be provided
          for all, for specific sets of, or for specific content items
          delivered using HTTP.  A CDNI implementation that does not
          support this optional CDNI Metadata Distribution Interface
          mechanism MUST ignore this log format indication and generate
          CDNI logging format for HTTP Adaptive Streaming using the
          default set of CDNI Logging fields.  (Note: this function is
          not concluded to be in Metadata Interface or Control
          Interface)

   MI-20  [MED] The CDNI Metadata Distribution interface should allow
          the Upstream CDN to signal to the Downstream CDN the Content
          Collection ID value for all, for specific sets of, or for
          specific content items delivered using HTTP.  Whenever the

Leung & Lee             Expires October 11, 2013               [Page 17]
Internet-Draft              CDNI Requirements                 April 2013

          Downstream CDN is instructed by the Upstream CDN to report the
          Content Collection ID field in the log records, the Downstream
          CDN is to use the value provided through the CDNI Metadata
          interface for the corresponding content.  Note the Session ID
          field along with Content Collection ID may be used for HTTP
          Adaptive Streaming content.

   MI-21  [MED] The CDNI Metadata Distribution interface should allow
          the Upstream CDN to signal to the Downstream CDN the
          Authorization Group ID value for all the related HTTP Adaptive
          Streamin content (i.e. manifest file and chunks).  The
          authorization result of a content (e.g. manifest file) is
          transferred over to related content (e.g. chunks).  [Ed: need
          to improve wording?]

8.  CDNI Logging Interface Requirements

   This section identifies the requirements related to the CDNI Logging
   interface (LI).  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.

   LI-1   [HIGH] The CDNI logging architecture and interface shall
          ensure reliable transfer of CDNI logging information across
          CDNs.

   LI-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.

   LI-3   [MED] In the case of cascaded CDNs, the CDNI Logging interface
          should 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.

   LI-4   [HIGH] The CDNI Logging interface shall support batch/offline
          exchange of logging records.

   LI-5   [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)

Leung & Lee             Expires October 11, 2013               [Page 18]
Internet-Draft              CDNI Requirements                 April 2013

   LI-6   [HIGH] The CDNI Logging interface shall define a log file
          format and a set of fields to be exported for various CDNI
          logging events.

   LI-7   [HIGH] The CDNI Logging interface shall define a transport
          mechanism to exchange CDNI Logging files.

   LI-8   [MED] The CDNI Logging interface should allow a CDN to query
          another CDN for relevant current logging records (e.g.  For
          on-demand access to real-time logging information).

   LI-9   [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).

   LI-10  [LOW] The CDNI Logging interface may 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 may support the Upstream CDN to
          indicate the nature and contents of the performance data to be
          reported by the Downstream CDN.

   LI-11  [MED] The CDNI Logging interface should 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.

   LI-12  [MED] In the case of cascaded CDNs, the CDNI Logging interface
          should 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.

   LI-13  [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.

Leung & Lee             Expires October 11, 2013               [Page 19]
Internet-Draft              CDNI Requirements                 April 2013

   LI-14  [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.

   LI-15  [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.

   LI-16  [HIGH] The CDNI Logging interface shall allow a CDN to notify
          another CDN about which CDNI logging information is available
          for transfer and/or no longer available (e.g. it exceeded some
          logging retention period or some logging retention volume).

   LI-17  [MED] The CDNI Logging interface should support the ability
          for the Downstream CDN to include the Content Collection ID
          and Session ID fields in CDNI log entries generated for HTTP
          Adaptive Streaming content.

9.  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

Leung & Lee             Expires October 11, 2013               [Page 20]
Internet-Draft              CDNI Requirements                 April 2013

          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).

10.  IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.

11.  Security Considerations

   This document discusses CDNI security requirements in Section 9.

12.  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

Leung & Lee             Expires October 11, 2013               [Page 21]
Internet-Draft              CDNI Requirements                 April 2013

      grant.watson@bt.com

13.  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.

   Ray Brandenburg, Matt Caufield, and Francois Le Faucheur/Gilles
   Bertrand provided valuable inputs for HTTP Adaptive Streaming, CDNI
   Metadata interface, and CDNI Logging interface, respectively.

14.  Appendix: Requirements Mapping

   The labels and numbers changed in version 6 of this document as part
   of the requirements cleanup and structuring changes due to
   introduction of the new CDNI request routing/Redirection Interface
   and CDNI request routing/Footprint & Capabilities advertisement
   interface.  There are some CDNI drafts that have referenced the
   requirements in this document.  Therefore, the following table
   provides the mapping of the requirement label and numbering.

Leung & Lee             Expires October 11, 2013               [Page 22]
Internet-Draft              CDNI Requirements                 April 2013

          +--------------------+-------------------------------+
          | Version 5          | Version 6                     |
          +--------------------+-------------------------------+
          | GEN-13             | Removed                       |
          | GEN-14             | GEN-13                        |
          | CNTL-#             | CI-# (label changed)          |
          | CNTL-1             | CI-1 and CI-3                 |
          | CNTL-2 to CNTL-9   | CI-4 to CI-11                 |
          | CNTL-10            | FCI-6                         |
          | CNTL-11            | CI-12                         |
          | CNTL-12            | CI-2                          |
          | REQ-#              | RI-# or FCI-# (label changed) |
          | REQ-1 to REQ-4     | FCI-1 to FCI-4                |
          | REQ-5 to REQ-19    | RI-1 to RI-15                 |
          | REQ-20             | FCI-5                         |
          | META-#             | MI-# (label changed)          |
          | META-13            | Removed                       |
          | META-14 to META-22 | MI-13 to MI-21                |
          | LOG-#              | LI-# (label changed)          |
          | LOG-4              | Removed                       |
          | LOG-5 to LOG-18    | LI-4 to LI-17                 |
          +--------------------+-------------------------------+

                    Requirement Reference Mapping Table

15.  References

15.1.  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.

   [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.

   [RFC6707]  Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
              Distribution Network Interconnection (CDNI) Problem
              Statement", RFC 6707, September 2012.

   [RFC6770]  Bertrand, G., Stephan, E., Burbridge, T., Eardley, P., Ma,
              K., and G. Watson, "Use Cases for Content Delivery Network
              Interconnection", RFC 6770, November 2012.

Leung & Lee             Expires October 11, 2013               [Page 23]
Internet-Draft              CDNI Requirements                 April 2013

15.2.  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.

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

Leung & Lee             Expires October 11, 2013               [Page 24]