





Internet Engineering Task Force (IETF)               F. Le Faucheur, Ed.
Request for Comments: 7937
Category: Standards Track                               G. Bertrand, Ed.
ISSN: 2070-1721
                                                         I. Oprescu, Ed.

                                                          R. Peterkofsky
                                                             Google Inc.
                                                             August 2016


 Content Distribution Network Interconnection (CDNI) Logging Interface

Abstract

   This memo specifies the Logging interface between a downstream
   Content Distribution Network (dCDN) and an upstream CDN (uCDN) that
   are interconnected as per the CDN Interconnection (CDNI) framework.
   First, it describes a reference model for CDNI logging.  Then, it
   specifies the CDNI Logging File format and the actual protocol for
   exchange of CDNI Logging Files.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7937.
















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Copyright Notice

   Copyright (c) 2016 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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   5
   2.  CDNI Logging Reference Model  . . . . . . . . . . . . . . . .   5
     2.1.  CDNI Logging Interactions . . . . . . . . . . . . . . . .   5
     2.2.  Overall Logging Chain . . . . . . . . . . . . . . . . . .   9
       2.2.1.  Logging Generation and During-Generation Aggregation   10
       2.2.2.  Logging Collection  . . . . . . . . . . . . . . . . .  11
       2.2.3.  Logging Filtering . . . . . . . . . . . . . . . . . .  11
       2.2.4.  Logging Rectification and Post-Generation Aggregation  12
       2.2.5.  Log-Consuming Applications  . . . . . . . . . . . . .  13
         2.2.5.1.  Maintenance and Debugging . . . . . . . . . . . .  13
         2.2.5.2.  Accounting  . . . . . . . . . . . . . . . . . . .  14
         2.2.5.3.  Analytics and Reporting . . . . . . . . . . . . .  14
         2.2.5.4.  Content Protection  . . . . . . . . . . . . . . .  14
         2.2.5.5.  Notions Common to Multiple Log-Consuming
                   Applications  . . . . . . . . . . . . . . . . . .  15
   3.  CDNI Logging File . . . . . . . . . . . . . . . . . . . . . .  17
     3.1.  Rules . . . . . . . . . . . . . . . . . . . . . . . . . .  17
     3.2.  CDNI Logging File Structure . . . . . . . . . . . . . . .  18
     3.3.  CDNI Logging Directives . . . . . . . . . . . . . . . . .  21
     3.4.  CDNI Logging Records  . . . . . . . . . . . . . . . . . .  26
       3.4.1.  HTTP Request Logging Record . . . . . . . . . . . . .  27
     3.5.  CDNI Logging File Extension . . . . . . . . . . . . . . .  38
     3.6.  CDNI Logging File Examples  . . . . . . . . . . . . . . .  38
     3.7.  Cascaded CDNI Logging Files Example . . . . . . . . . . .  42








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   4.  Protocol for Exchange of CDNI Logging File after Full
       Collection  . . . . . . . . . . . . . . . . . . . . . . . . .  44
     4.1.  CDNI Logging Feed . . . . . . . . . . . . . . . . . . . .  45
       4.1.1.  Atom Formatting . . . . . . . . . . . . . . . . . . .  45
       4.1.2.  Updates to Log Files and the Feed . . . . . . . . . .  46
       4.1.3.  Redundant Feeds . . . . . . . . . . . . . . . . . . .  47
       4.1.4.  Example CDNI Logging Feed . . . . . . . . . . . . . .  47
     4.2.  CDNI Logging File Pull  . . . . . . . . . . . . . . . . .  49
   5.  Protocol for Exchange of CDNI Logging File During Collection   50
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  51
     6.1.  CDNI Logging Directive Names Registry . . . . . . . . . .  51
     6.2.  CDNI Logging File version Registry  . . . . . . . . . . .  51
     6.3.  CDNI Logging record-types Registry  . . . . . . . . . . .  52
     6.4.  CDNI Logging Field Names Registry . . . . . . . . . . . .  53
     6.5.  CDNI Logging Payload Type . . . . . . . . . . . . . . . .  55
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  55
     7.1.  Authentication, Authorization, Confidentiality, and
           Integrity Protection  . . . . . . . . . . . . . . . . . .  55
     7.2.  Denial of Service . . . . . . . . . . . . . . . . . . . .  56
     7.3.  Privacy . . . . . . . . . . . . . . . . . . . . . . . . .  57
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  58
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  58
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  61
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  63
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  63

1.  Introduction

   This memo specifies the CDNI Logging interface between a downstream
   CDN (dCDN) and an upstream CDN (uCDN).  First, it describes a
   reference model for CDNI logging.  Then, it specifies the CDNI
   Logging File format and the actual protocol for exchange of CDNI
   Logging Files.

   The reader should be familiar with the following documents:

   o  CDNI problem statement [RFC6707] and framework [RFC7336], which
      identify a Logging interface,

   o  Section 8 of [RFC7337], which specifies a set of requirements for
      Logging,

   o  [RFC6770] outlines real world use cases for interconnecting CDNs.
      These use cases require the exchange of Logging information
      between the dCDN and the uCDN.






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   As stated in [RFC6707], "the CDNI Logging interface enables details
   of content distribution and delivery activities to be exchanged
   between interconnected CDNs."

   The present document describes:

   o  The CDNI Logging reference model (Section 2)

   o  The CDNI Logging File format (Section 3)

   o  The CDNI Logging File Exchange protocol (Section 4)

1.1.  Terminology

   In this document, the first letter of each CDNI-specific term is
   capitalized.  We adopt the terminology described in [RFC6707] and
   [RFC7336], and extend it with the additional terms defined below.

   Intra-CDN Logging information: Logging information generated and
   collected within a CDN.  The format of the Intra-CDN Logging
   information may be different from the format of the CDNI Logging
   information.

   CDNI Logging information: Logging information exchanged across CDNs
   using the CDNI Logging interface.

   Logging information: Logging information generated and collected
   within a CDN or obtained from another CDN using the CDNI Logging
   interface.

   CDNI Logging Field: An atomic element of information that can be
   included in a CDNI Logging Record.  The time an event/task started,
   the IP address of an end user to whom content was delivered, and the
   Uniform Resource Identifier (URI) of the content delivered, are
   examples of CDNI Logging fields.

   CDNI Logging Record: An information record providing information
   about a specific event.  This comprises a collection of CDNI Logging
   fields.

   CDNI Logging File: A file containing CDNI Logging Records, as well as
   additional information facilitating the processing of the CDNI
   Logging Records.

   CDN Reporting: The process of providing the relevant information that
   will be used to create a formatted content delivery report provided
   to the Content Service Provider (CSP) in deferred time.  Such
   information typically includes aggregated data that can cover a large



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   period of time (e.g., from hours to several months).  Uses of
   reporting include the collection of charging data related to CDN
   services and the computation of Key Performance Indicators (KPIs).

   CDN Monitoring: The process of providing or displaying content
   delivery information in a timely fashion with respect to the
   corresponding deliveries.  Monitoring typically includes visibility
   of the deliveries in progress for service operation purposes.  It
   presents a view of the global health of the services as well as
   information on usage and performance, for network services
   supervision and operation management.  In particular, monitoring data
   can be used to generate alarms.

1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in RFC
   2119 [RFC2119].

2.  CDNI Logging Reference Model

2.1.  CDNI Logging Interactions

   The CDNI logging reference model between a given uCDN and a given
   dCDN involves the following interactions:

   o  customization by the uCDN of the CDNI Logging information to be
      provided by the dCDN to the uCDN (e.g., control of which CDNI
      Logging fields are to be communicated to the uCDN for a given task
      performed by the dCDN or control of which types of events are to
      be logged).  The dCDN takes into account this CDNI Logging
      customization information to determine what Logging information to
      provide to the uCDN, but it may, or may not, take into account
      this CDNI Logging customization information to influence what CDN
      Logging information is to be generated and collected within the
      dCDN (e.g., even if the uCDN requests a restricted subset of the
      Logging information, the dCDN may elect to generate a broader set
      of Logging information).  The mechanism to support the
      customization by the uCDN of CDNI Logging information is outside
      the scope of this document and is left for further study.  Until
      such a mechanism is available, the uCDN and dCDN are expected to
      agree off-line on what exact set of CDNI Logging information is to
      be provided by the dCDN to the uCDN, and to rely on management-
      plane actions to configure the CDNI Logging functions in the dCDN
      to generate this information set and in the uCDN to expect this
      information set.




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   o  generation and collection by the dCDN of the intra-CDN Logging
      information related to the completion of any task performed by the
      dCDN on behalf of the uCDN (e.g., delivery of the content to an
      end user) or related to events happening in the dCDN that are
      relevant to the uCDN (e.g., failures or unavailability in dCDN).
      This takes place within the dCDN and does not directly involve
      CDNI interfaces.

   o  communication by the dCDN to the uCDN of the Logging information
      collected by the dCDN relevant to the uCDN.  This is supported by
      the CDNI Logging interface and is in the scope of the present
      document.  For example, the uCDN may use this Logging information
      to charge the CSP, to perform analytics and monitoring for
      operational reasons, to provide analytics and monitoring views on
      its content delivery to the CSP, or to perform troubleshooting.
      This document exclusively specifies non-real-time exchange of
      Logging information.  Closer to real-time exchange of Logging
      information (say sub-minute or sub-second) is outside the scope of
      the present document and is left for further study.  This document
      exclusively specifies exchange of Logging information related to
      content delivery.  Exchange of Logging information related to
      operational events (e.g., dCDN request routing function
      unavailable and content acquisition failure by dCDN) for audit or
      operational reactive adjustments by uCDN is outside the scope of
      the present document and is left for further study.

   o  customization by the dCDN of the CDNI Logging information to be
      provided by the uCDN on behalf of the dCDN.  The mechanism to
      support the customization by the dCDN of CDNI Logging information
      is outside the scope of this document and is left for further
      study.

   o  generation and collection by the uCDN of Intra-CDN Logging
      information related to the completion of any task performed by the
      uCDN on behalf of the dCDN (e.g., serving of content by uCDN to
      dCDN for acquisition purposes by dCDN) or related to events
      happening in the uCDN that are relevant to the dCDN.  This takes
      place within the uCDN and does not directly involve CDNI
      interfaces.

   o  communication by the uCDN to the dCDN of the Logging information
      collected by the uCDN relevant to the dCDN.  For example, the dCDN
      might potentially benefit from this information for security
      auditing or content acquisition troubleshooting.  This is outside
      the scope of this document and is left for further study.






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   Figure 1 provides an example of CDNI Logging interactions (focusing
   only on the interactions that are in the scope of this document) in a
   particular scenario where four CDNs are involved in the delivery of
   content from a given CSP: the uCDN has a CDNI interconnection with
   dCDN-1 and dCDN-2.  In turn, dCDN-2 has a CDNI interconnection with
   dCDN-3, where dCDN-2 is acting as an upstream CDN relative to dCDN-3.
   In this example, uCDN, dCDN-1, dCDN-2, and dCDN-3 all participate in
   the delivery of content for the CSP.  In this example, the CDNI
   Logging interface enables the uCDN to obtain Logging information from
   all the dCDNs involved in the delivery.  In the example, the uCDN
   uses the Logging information:

   o  to analyze the performance of the delivery performed by the dCDNs
      and to adjust its operations after the fact (e.g., request
      routing) as appropriate.

   o  to provide (non-real-time) reporting and monitoring information to
      the CSP.

   For instance, the uCDN merges Logging information, extracts relevant
   KPIs, and presents a formatted report to the CSP, in addition to a
   bill for the content delivered by uCDN itself or by its dCDNs on the
   CSP's behalf.  The uCDN may also provide Logging information as raw
   log files to the CSP, so that the CSP can use its own logging
   analysis tools.


























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                   +-----+
                   | CSP |
                   +-----+
                      ^ Reporting and monitoring data
                      * Billing
                   ,--*--.
       Logging  ,-'       `-.
       Data  =>(     uCDN    )<=   Logging
          //   `-.       _,-'   \\  Data
          ||      `-'-'-'      ||
       ,-----.                 ,-----.
    ,-'       `-.           ,-'       `-.
   (   dCDN-1    )         (   dCDN-2    )<==  Logging
    `-.       ,-'          `-.      _,-'    \\ Data
      `--'--'                  `--'-'        ||
                                          ,-----.
                                        ,'       `-.
                                       (  dCDN-3    )
                                        `.       ,-'
                                          `--'--'

   ===> CDNI Logging interface
   ***> outside the scope of CDNI

        Figure 1: Interactions in the CDNI Logging Reference Model

   A downstream CDN relative to uCDN (e.g., dCDN-2) integrates the
   relevant Logging information obtained from its own downstream CDNs
   (i.e., dCDN-3) in the Logging information that it provides to the
   uCDN, so that the uCDN ultimately obtains all Logging information
   relevant to a CSP for which it acts as the authoritative CDN.  Such
   aggregation is further discussed in Section 3.7.

   Note that the format of Logging information that a CDN provides over
   the CDNI interface might be different from the one that the CDN uses
   internally.  In this case, the CDN needs to reformat the Logging
   information before it provides this information to the other CDN over
   the CDNI Logging interface.  Similarly, a CDN might reformat the
   Logging information that it receives over the CDNI Logging interface
   before injecting it into its log-consuming applications or before
   providing some of this Logging information to the CSP.  Such
   reformatting operations introduce latency in the logging distribution
   chain and introduce a processing burden.  Therefore, there are
   benefits in specifying CDNI Logging formats that are suitable for use
   inside CDNs and also are close to the intra-CDN Logging formats
   commonly used in CDNs today.





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2.2.  Overall Logging Chain

   This section discusses the overall logging chain within and across
   CDNs to clarify how CDN Logging information is expected to fit in
   this overall chain.  Figure 2 illustrates the overall logging chain
   within the dCDN, across CDNs using the CDNI Logging interface, and
   within the uCDN.  Note that the logging chain illustrated in the
   figure is obviously only an example and varies depending on the
   specific environments.  For example, there may be more or fewer
   instantiations of each entity (e.g., there may be 4 log-consuming
   applications in a given CDN).  As another example, there may be one
   instance of a Rectification process per log-consuming application
   instead of a shared one.






































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             Log-Consuming    Log-Consuming
                 App              App
                 ^                ^
                 |                |
           Rectification----------
           ^
           |
           Filtering
            ^
            |
        Collection
        ^        ^
        |        |
        |     Generation
        |
        |                                                     uCDN
   CDNI Logging ---------------------------------------------------
   exchange                                                   dCDN
        ^
        |          Log-Consuming    Log-Consuming
        |                 App              App
        |                  ^               ^
        |                  |               |
   Rectification     Rectification---------
           ^        ^
           |        |
           Filtering
            ^
            |
         Collection
         ^        ^
         |        |
   Generation    Generation

            Figure 2: CDNI Logging in the Overall Logging Chain

   The following subsections describe each of the processes potentially
   involved in the logging chain of Figure 2.

2.2.1.  Logging Generation and During-Generation Aggregation

   CDNs typically generate Logging information for all significant task
   completions, events, and failures.  Logging information is typically
   generated by many devices in the CDN including the surrogates, the
   request routing system, and the control system.






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   The amount of Logging information generated can be huge.  Therefore,
   during contract negotiations, interconnected CDNs often agree on a
   retention duration for Logging information, and/or potentially on a
   maximum volume of Logging information that the dCDN ought to keep.
   If this volume is exceeded, the dCDN is expected to alert the uCDN
   but may not keep more Logging information for the considered time
   period.  In addition, CDNs may aggregate Logging information and
   transmit only summaries for some categories of operations instead of
   the full Logging information.  Note that such aggregation leads to an
   information loss, which may be problematic for some usages of the
   Logging information (e.g., debugging).

   [RFC6983] discusses logging for HTTP Adaptive Streaming (HAS).  In
   accordance with the recommendations articulated there, it is expected
   that a surrogate will generate separate Logging information for
   delivery of each chunk of HAS content.  This ensures that separate
   Logging information can then be provided to interconnected CDNs over
   the CDNI Logging interface.  Still in line with the recommendations
   of [RFC6983], the Logging information for per-chunk delivery may
   include some information (a Content Collection IDentifier and a
   Session IDentifier) intended to facilitate subsequent post-generation
   aggregation of per-chunk logs into per-session logs.  Note that a CDN
   may also elect to generate aggregate per-session logs when performing
   HAS delivery, but this needs to be in addition to, and not instead
   of, the per-chunk delivery logs.  We note that aggregate per-session
   logs for HAS delivery are for further study and are outside the scope
   of this document.

2.2.2.  Logging Collection

   This is the process that continuously collects Logging information
   generated by the log-generating entities within a CDN.

   In a CDNI environment, in addition to collecting Logging information
   from log-generating entities within the local CDN, the Collection
   process also collects Logging information provided by another CDN, or
   other CDNs, through the CDNI Logging interface.  This is illustrated
   in Figure 2 where we see that the Collection process of the uCDN
   collects Logging information from log-generating entities within the
   uCDN as well as Logging information coming from the dCDNs through the
   CDNI Logging interface.

2.2.3.  Logging Filtering

   A CDN may be required to only present different subsets of the whole
   Logging information collected to various log-consuming applications.
   This is achieved by the Filtering process.




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   In particular, the Filtering process can also filter the right subset
   of Logging information that needs to be provided to a given
   interconnected CDN.  For example, the filtering process in the dCDN
   can be used to ensure that only the Logging information related to
   tasks performed on behalf of a given uCDN are made available to that
   uCDN (thereby filtering out all the Logging information related to
   deliveries by the dCDN of content for its own CSPs).  Similarly, the
   Filtering process may filter or partially mask some fields, for
   example, to protect end-users' privacy when communicating CDNI
   Logging information to another CDN.  Filtering of Logging information
   prior to communication of this information to other CDNs via the CDNI
   Logging interface requires that the downstream CDN can recognize the
   subset of Logging information that relates to each interconnected
   CDN.

   The CDN will also filter some internal scope information such as
   information related to its internal alarms (security, failures, load,
   etc.).

   In some use cases described in [RFC6770], the interconnected CDNs do
   not want to disclose details on their internal topology.  The
   filtering process can then also filter confidential data on the
   dCDNs' topology (number of servers, location, etc.).  In particular,
   information about the requests served by each Surrogate may be
   confidential.  Therefore, the Logging information needs to be
   protected so that data such as the Surrogates' hostnames are not
   disclosed to the uCDN.  In the "Inter-Affiliates Interconnection" use
   case, this information may be disclosed to the uCDN because both the
   dCDN and the uCDN are operated by entities of the same group.

2.2.4.  Logging Rectification and Post-Generation Aggregation

   If Logging information is generated periodically, it is important
   that the sessions that start in one Logging period and end in another
   are correctly reported.  If they are reported in the starting period,
   then the Logging information of this period will be available only
   after the end of the session, which delays the Logging information
   generation.  A simple approach is to provide the complete Logging
   Record for a session in the Logging Period of the session end.

   A Logging rectification/update mechanism could be useful to reach a
   good trade-off between the Logging information generation delay and
   the Logging information accuracy.

   In the presence of HAS, some log-consuming applications can benefit
   from aggregate per-session logs.  For example, for analytics, per-
   session logs allow display of session-related trends, which are much
   more meaningful for some types of analysis than chunk-related trends.



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   In the case where aggregate logs have been generated directly by the
   log-generating entities, those can be used by the applications.  In
   the case where aggregate logs have not been generated, the
   Rectification process can be extended with a Post-Generation
   Aggregation process that generates per-session logs from the per-
   chunk logs, possibly leveraging the information included in the per-
   chunk logs for that purpose (Content Collection IDentifier and a
   Session IDentifier).  However, in accordance with [RFC6983], this
   document does not define the exchange of such aggregate logs on the
   CDNI Logging interface.  We note that this is for further study and
   is outside the scope of this document.

2.2.5.  Log-Consuming Applications

2.2.5.1.  Maintenance and Debugging

   Logging information is useful to permit the detection (and limit the
   risk) of content delivery failures.  In particular, Logging
   information facilitates the detection of configuration issues.

   To detect faults, Logging information needs to report the success and
   failure of CDN-delivery operations.  The uCDN can summarize such
   information into KPIs.  For instance, Logging information needs to
   allow the computation of the number of times, during a given time
   period, that content delivery related to a specific service succeeds
   or fails.

   Logging information enables the CDN providers to identify and
   troubleshoot performance degradations.  In particular, Logging
   information enables tracking of traffic data (e.g., the amount of
   traffic that has been forwarded by a dCDN on behalf of an uCDN over a
   given period of time), which is particularly useful for CDN and
   network planning operations.

   Some of these maintenance and debugging applications only require
   aggregate Logging information highly compatible with the use of
   anonymization of IP addresses (as supported by the present document
   and specified in the definition of the c-groupid field in
   Section 3.4.1).  However, in some situations, it may be useful, where
   compatible with privacy protection, to access some CDNI Logging
   Records containing full non-anonymized IP addresses.  This is allowed
   in the definition of the c-groupid (in Section 3.4.1), with very
   significant privacy protection limitations that are discussed in the
   definition of the c-groupid field.  For example, this may be useful
   for detailed fault tracking of a particular end-user content delivery
   issue.  Where there is a hard requirement by uCDN or CSP to associate
   a given end user to individual CDNI Logging Records (e.g., to allow a
   posteriori analysis of individual delivery, for example, in



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   situations of performance-based penalties), instead of using
   aggregates containing a single client as discussed in the c-groupid
   field definition, an alternate approach is to ensure that a client
   identifier is embedded in the request fields that can be logged in a
   CDNI Logging Record (for example, by including the client identifier
   in the URI query string or in an HTTP Header).  That latter approach
   offers two significant benefits: first, the aggregate inside the
   c-groupid can contain more than one client, thereby ensuring stronger
   privacy protection; second, it allows a reliable identification of
   the client while IP address does not in many situations (e.g., behind
   NAT, where dynamic IP addresses are used and reused, etc.).  However,
   care SHOULD be taken so that the client identifiers exposed in other
   fields of the CDNI Records cannot themselves be linked back to actual
   users.

2.2.5.2.  Accounting

   Logging information is essential for accounting, to permit inter-CDN
   billing and CSP billing by uCDNs.  For instance, Logging information
   provided by dCDNs enables the uCDN to compute the total amount of
   traffic delivered by every dCDN for a particular Content Provider, as
   well as the associated bandwidth usage (e.g., peak, 95th percentile),
   and the maximum number of simultaneous sessions over a given period
   of time.

2.2.5.3.  Analytics and Reporting

   The goals of analytics include gathering any relevant information in
   order to be able to develop statistics on content download, analyze
   user behavior, and monitor the performance and quality of content
   delivery.  For instance, Logging information enables the CDN
   providers to report on content consumption (e.g., delivered sessions
   per content) in a specific geographic area.

   The goal of reporting is to gather any relevant information to
   monitor the performance and quality of content delivery, and allow
   detection of delivery issues.  For instance, reporting could track
   the average delivery throughput experienced by end users in a given
   region for a specific CSP or content set over a period of time.

2.2.5.4.  Content Protection

   The goal of content protection is to prevent and monitor unauthorized
   access, misuse, modification, and denial of access to content.  A set
   of information is logged in a CDN for security purposes.  In
   particular, a record of access to content is usually collected to
   permit the CSP to detect infringements of content delivery policies
   and other abnormal end-user behaviors.



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2.2.5.5.  Notions Common to Multiple Log-Consuming Applications

2.2.5.5.1.  Logging Information Views

   Within a given log-consuming application, different views may be
   provided to different users depending on privacy, business, and
   scalability constraints.

   For example, an analytics tool run by the uCDN can provide one view
   to a uCDN operator that exploits all the Logging information
   available to the uCDN, while the tool may provide a different view to
   each CSP exploiting only the Logging information related to the
   content of the given CSP.

   As another example, maintenance and debugging tools may provide
   different views to different CDN operators, based on their
   operational role.

2.2.5.5.2.  Key Performance Indicators (KPIs)

   This section presents, for explanatory purposes, a non-exhaustive
   list of Key Performance Indicators (KPIs) that can be extracted/
   produced from logs.

   Multiple log-consuming applications, such as analytics, monitoring,
   and maintenance applications, often compute and track such KPIs.

   In a CDNI environment, depending on the situation, these KPIs may be
   computed by the uCDN or by the dCDN.  But it is usually the uCDN that
   computes KPIs, because the uCDN and dCDN may have different
   definitions of the KPIs and the computation of some KPIs requires a
   vision of all the deliveries performed by the uCDN and all its dCDNs.

   Here is a list of important examples of KPIs:

   o  Number of delivery requests received from end users in a given
      region for each piece of content, during a given period of time
      (e.g., hour/day/week/month)

   o  Percentage of delivery successes/failures among the aforementioned
      requests

   o  Number of failures listed by failure type (e.g., HTTP error code)
      for requests received from end users in a given region and for
      each piece of content, during a given period of time (e.g.,
      hour/day/week/month)





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   o  Number and cause of premature delivery termination for end users
      in a given region and for each piece of content, during a given
      period of time (e.g., hour/day/week/month)

   o  Maximum and mean number of simultaneous sessions established by
      end users in a given region, for a given Content Provider, and
      during a given period of time (e.g., hour/day/week/month)

   o  Volume of traffic delivered for sessions established by end users
      in a given region, for a given Content Provider, and during a
      given period of time (e.g., hour/day/week/month)

   o  Maximum, mean, and minimum delivery throughput for sessions
      established by end users in a given region, for a given Content
      Provider, and during a given period of time (e.g., hour/day/week/
      month)

   o  Cache-hit and byte-hit ratios for requests received from end users
      in a given region for each piece of content, during a given period
      of time (e.g., hour/day/week/month)

   o  Top 10 most popularly requested contents (during a given day/week/
      month)

   o  Terminal type (mobile, PC, Set-Top Box (STB), if this information
      can be acquired from the browser type inferred from the User Agent
      string, for example)

   Additional KPIs can be computed from other sources of information
   than the Logging information, for instance, data collected by a
   content portal or by specific client-side application programming
   interfaces.  Such KPIs are out of scope for the present document.

   The KPIs used depend strongly on the considered log-consuming
   application -- the CDN operator may be interested in different
   metrics than the CSP.  In particular, CDN operators are often
   interested in delivery and acquisition performance KPIs, information
   related to Surrogates' performance, caching information to evaluate
   the cache-hit ratio, information about the delivered file size to
   compute the volume of content delivered during peak hour, etc.

   Some of the KPIs, for instance those providing an instantaneous
   vision of the active sessions for a given CSP's content, are useful
   essentially if they are provided in a timely manner.  By contrast,
   some other KPIs, such as those averaged over a long period of time,
   can be provided in non-real-time.





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3.  CDNI Logging File

3.1.  Rules

   This specification uses the Augmented Backus-Naur Form (ABNF)
   notation and core rules of [RFC5234].  In particular, the present
   document uses the following rules from [RFC5234]:

      CR = %x0D ; carriage return

      ALPHA = %x41-5A / %x61-7A ; A-Z / a-z

      DIGIT = %x30-39 ; 0-9

      DQUOTE = %x22 ; " (Double Quote)

      CRLF = CR LF ; Internet standard newline

      HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"

      HTAB = %x09 ; horizontal tab

      LF = %x0A ; linefeed

      VCHAR = %x21-7E ; visible (printing) characters

      OCTET = %x00-FF ; 8 bits of data

   The present document also uses the following rules from [RFC3986]:

      host = as specified in Section 3.2.2 of [RFC3986].

      IPv4address = as specified in Section 3.2.2 of [RFC3986].

      IPv6address = as specified in Section 3.2.2 of [RFC3986].

      partial-time = as specified in Section 5.6 of [RFC3339].

   The present document also defines the following additional rules:

      ADDRESS = IPv4address / IPv6address

      ALPHANUM = ALPHA / DIGIT

      DATE = 4DIGIT "-" 2DIGIT "-" 2DIGIT

         ; Dates are encoded as "full-date" specified in [RFC3339].




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      DEC = 1*DIGIT ["." 1*DIGIT]

      NAMEFORMAT = ALPHANUM *(ALPHANUM / "_" / "-")

      QSTRING = DQUOTE *(NDQUOTE / PCT-ENCODED) DQUOTE

      NDQUOTE = %x20-21 / %x23-24 / %x26-7E / UTF8-2 / UTF8-3 / UTF8-4

         ; whereby a DQUOTE is conveyed inside a QSTRING unambiguously
         ; by escaping it with PCT-ENCODED.

      PCT-ENCODED = "%" HEXDIG HEXDIG

         ; percent encoding is used for escaping octets that might be
         ; possible in HTTP headers such as bare CR, bare LF, CR LF,
         ; HTAB, SP, or null.  These octets are rendered with percent
         ; encoding in ABNF as specified by [RFC3986] in order to avoid
         ; considering them as separators for the Logging Records.

      NHTABSTRING = 1*(SP / VCHAR)

      TIME = partial-time

      USER-COMMENT = *(SP / VCHAR / UTF8-2 / UTF8-3 / UTF8-4)

3.2.  CDNI Logging File Structure

   As defined in Section 1.1, a CDNI Logging Field is an atomic Logging
   information element, a CDNI Logging Record is a collection of CDNI
   Logging fields containing all logging information corresponding to a
   single logging event, and a CDNI Logging File contains a collection
   of CDNI Logging Records.  This structure is illustrated in Figure 3.
   The use of a file structure for transfer of CDNI Logging information
   is selected since this is the most common practice today for exchange
   of Logging information within and across CDNs.
















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   +----------------------------------------------------------+
   |CDNI Logging File                                         |
   |                                                          |
   | #Directive 1                                             |
   | #Directive 2                                             |
   | ...                                                      |
   | #Directive P                                             |
   |                                                          |
   | +------------------------------------------------------+ |
   | |CDNI Logging Record 1                                 | |
   | |  +-------------+ +-------------+     +-------------+ | |
   | |  |CDNI Logging | |CDNI Logging | ... |CDNI Logging | | |
   | |  |   Field 1   | |   Field 2   |     |   Field N   | | |
   | |  +-------------+ +-------------+     +-------------+ | |
   | +------------------------------------------------------+ |
   |                                                          |
   | +------------------------------------------------------+ |
   | |CDNI Logging Record 2                                 | |
   | |  +-------------+ +-------------+     +-------------+ | |
   | |  |CDNI Logging | |CDNI Logging | ... |CDNI Logging | | |
   | |  |   Field 1   | |   Field 2   |     |   Field N   | | |
   | |  +-------------+ +-------------+     +-------------+ | |
   | +------------------------------------------------------+ |
   |                                                          |
   |  ...                                                     |
   |                                                          |
   | #Directive P+1                                           |
   |                                                          |
   |  ...                                                     |
   |                                                          |
   | +------------------------------------------------------+ |
   | |CDNI Logging Record M                                 | |
   | |  +-------------+ +-------------+     +-------------+ | |
   | |  |CDNI Logging | |CDNI Logging | ... |CDNI Logging | | |
   | |  |   Field 1   | |   Field 2   |     |   Field N   | | |
   | |  +-------------+ +-------------+     +-------------+ | |
   | +------------------------------------------------------+ |
   |                                                          |
   |                                                          |
   | #Directive P+Q                                           |
   +----------------------------------------------------------+

                   Figure 3: Structure of Logging Files








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   The CDNI Logging File format is inspired from the W3C Extended Log
   File Format [ELF].  However, it is fully specified by the present
   document.  Where the present document differs from the W3C Extended
   Log File Format, an implementation of the CDNI Logging interface MUST
   comply with the present document.  The W3C Extended Log File Format
   was used as a starting point, reused where possible, and expanded
   when necessary.

   Using a format that resembles the W3C Extended Log File Format is
   intended to keep the CDNI logging format close to the intra-CDN
   Logging information format commonly used in CDNs today, thereby
   minimizing systematic translation at the CDN/CDNI boundary.

   A CDNI Logging File MUST contain a sequence of lines containing US-
   ASCII characters [CHAR_SET] terminated by CRLF.  Each line of a CDNI
   Logging File MUST contain either a directive or a CDNI Logging
   Record.

   Directives record information about the CDNI Logging process itself.
   Lines containing directives MUST begin with the "#" character.
   Directives are specified in Section 3.3.

   Logging Records provide actual details of the logged event.  Logging
   Records are specified in Section 3.4.

   The CDNI Logging File has a specific structure.  It always starts
   with a directive line, and the first directive it contains MUST be
   the version.

   The directive lines form together a group that contains at least one
   directive line.  Each directives group is followed by a group of
   Logging Records.  The records group contains zero or more actual
   Logging Record lines about the event being logged.  A record line
   consists of the values corresponding to all or a subset of the
   possible Logging fields defined within the scope of the record-type
   directive.  These values MUST appear in the order defined by the
   fields directive.

   Note that future extensions MUST be compliant with the previous
   description.  The following examples depict the structure of a
   CDNILOGFILE as defined currently by the record-type
   "cdni_http_request_v1."









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      DIRLINE = "#" directive CRLF

      DIRGROUP = 1*DIRLINE

      RECLINE = <any subset of record values that match what is expected
      according to the fields directive within the immediately preceding
      DIRGROUP>

      RECGROUP = *RECLINE

      CDNILOGFILE = 1*(DIRGROUP RECGROUP)

3.3.  CDNI Logging Directives

   A CDNI Logging directive line contains the directive name followed by
   ":" HTAB and the directive value.

   Directive names MUST be of the format NAMEFORMAT.  All directive
   names MUST be registered in the "CDNI Logging Directives Names"
   registry.  Directive names are case-insensitive as per the basic ABNF
   ([RFC5234]).  Unknown directives MUST be ignored.  Directive values
   can have various formats.  All possible directive values for the
   record-type "cdni_http_request_v1" are further detailed in this
   section.

   The following example shows the structure of a directive and
   enumerates strictly the directive values presently defined in the
   version "cdni/1.0" of the CDNI Logging File.

      directive = DIRNAME ":" HTAB DIRVAL

      DIRNAME = NAMEFORMAT

      FIENAME = <any CDNI Logging field name registered in the CDNI
      Logging Field Names registry (Section 6.4) that is valid for the
      record type specified in the record-type directive.>

      DIRVAL = NHTABSTRING / QSTRING / host / USER-COMMENT / FIENAME
      *(HTAB FIENAME) / 64HEXDIG












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   An implementation of the CDNI Logging interface MUST support all of
   the following directives, listed below by their directive name:

   o  Version:

      *  Format: NHTABSTRING

      *  Directive value: Indicates the version of the CDNI Logging File
         format.  The entity transmitting a CDNI Logging File as per the
         present document MUST set the value to "cdni/1.0".  In the
         future, other versions of the CDNI Logging File might be
         specified; those would use a value different from "cdni/1.0",
         which allows the entity receiving the CDNI Logging File to
         identify the corresponding version.  CDNI Logging File versions
         are case-insensitive as per the basic ABNF ([RFC5234]).

      *  Occurrence: There MUST be one and only one instance of this
         directive per the CDNI Logging File.  It MUST be the first line
         of the CDNI Logging File.

      *  Example: "version: HTAB cdni/1.0".

   o  UUID:

      *  Format: NHTABSTRING

      *  Directive value: This a Uniform Resource Name (URN) from the
         Universally Unique IDentifier (UUID) URN namespace specified in
         [RFC4122].  The UUID contained in the URN uniquely identifies
         the CDNI Logging File.

      *  Occurrence: There MUST be one and only one instance of this
         directive per the CDNI Logging File.

      *  Example: "UUID: HTAB NHTABSTRING".

   o  Claimed-origin:

      *  Format: Host

      *  Directive value: This contains the claimed identification of
         the entity transmitting the CDNI Logging File (e.g., the host
         in a dCDN supporting the CDNI Logging interface) or the entity
         responsible for transmitting the CDNI Logging File (e.g., the
         dCDN).






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      *  Occurrence: There MUST be zero or exactly one instance of this
         directive per the CDNI Logging File.  This directive MAY be
         included by the dCDN.  It MUST NOT be included or modified by
         the uCDN.

      *  Example: "claimed-origin: HTAB host".

   o  Established-origin:

      *  Format: Host

      *  Directive value: This contains the identification, as
         established by the entity receiving the CDNI Logging File, of
         the entity transmitting the CDNI Logging File (e.g., the host
         in a dCDN supporting the CDNI Logging interface) or the entity
         responsible for transmitting the CDNI Logging File (e.g., the
         dCDN).

      *  Occurrence: There MUST be zero or exactly one instance of this
         directive per the CDNI Logging File.  This directive MAY be
         added by the uCDN (e.g., before storing the CDNI Logging File).
         It MUST NOT be included by the dCDN.  The mechanisms used by
         the uCDN to establish and validate the entity responsible for
         the CDNI Logging File is outside the scope of the present
         document.  We observe that, in particular, this may be achieved
         through authentication mechanisms that are part of the
         transport layer of the CDNI Logging File pull mechanism
         (Section 4.2).

      *  ABNF example: "established-origin: HTAB host".

   o  Remark:

      *  Format: USER-COMMENT

      *  Directive value: This contains comment information.  Data
         contained in this field is to be ignored by analysis tools.

      *  Occurrence: There MAY be zero, one, or any number of instances
         of this directive per the CDNI Logging File.

      *  Example: "remark: HTAB USER-COMMENT".









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   o  Record-type:

      *  Format: NAMEFORMAT

      *  Directive value: Indicates the type of the CDNI Logging Records
         that follow this directive, until another record-type directive
         appears in the CDNI Logging File (or the end of the CDNI
         Logging File).  This can be any CDNI Logging Record type
         registered in the "CDNI Logging record-types" registry
         (Section 6.3).  For example, this may be "cdni_http_request_v1"
         as specified in Section 3.4.1.  CDNI Logging record-types are
         case-insensitive as per the basic ABNF ([RFC5234]).

      *  Occurrence: There MUST be at least one instance of this
         directive per the CDNI Logging File.  The first instance of
         this directive MUST precede a fields directive and MUST precede
         all CDNI Logging Records.

      *  Example: "record-type: HTAB cdni_http_request_v1".

   o  Fields:

      *  Format: FIENAME *(HTAB FIENAME) ; where FIENAME can take any
         CDNI Logging field name registered in the "CDNI Logging Field
         Names" registry (Section 6.4) that is valid for the record type
         specified in the record-type directive.

      *  Directive value: This lists the names of all the fields for
         which a value is to appear in the CDNI Logging Records that
         follow the instance of this directive (until another instance
         of this directive appears in the CDNI Logging File).  The names
         of the fields, as well as their occurrences, MUST comply with
         the corresponding rules specified in the document referenced in
         the "CDNI Logging record-types" registry (Section 6.3) for the
         corresponding CDNI Logging record-type.

      *  Occurrence: There MUST be at least one instance of this
         directive per record-type directive.  The first instance of
         this directive for a given record-type MUST appear before any
         CDNI Logging Record for this record-type.  One situation where
         more than one instance of the fields directive can appear
         within a given CDNI Logging File is when there is a change, in
         the middle of a fairly large logging period, and in the
         agreement between the uCDN and the dCDN about the set of fields
         that are to be exchanged.  The multiple occurrences allow
         records with the old set of fields and records with the new set
         of fields to be carried inside the same Logging File.




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      *  Example: "fields: HTAB FIENAME * (HTAB FIENAME)".

   o  SHA256-hash:

      *  Format: 64HEXDIG

      *  Directive value: This directive permits the detection of a
         corrupted CDNI Logging File.  This can be useful, for instance,
         if a problem occurs on the file system of the dCDN Logging
         system and leads to a truncation of a Logging File.  The valid
         SHA256-hash value is included in this directive by the entity
         that transmits the CDNI Logging File.  It MUST be computed by
         applying the SHA-256 ([RFC6234]) cryptographic hash function on
         the CDNI Logging File, including all the directives and Logging
         Records, up to the SHA256-hash directive itself, excluding the
         SHA256-hash directive itself.  The SHA256-hash value MUST be
         represented as a 64-digit hexadecimal number encoded in US-
         ASCII (representing a 256 bit hash value).  The entity
         receiving the CDNI Logging File also computes, in a similar
         way, the SHA-256 hash on the received CDNI Logging File and
         compares this hash to the value of the SHA256-hash directive.
         If the two values are equal, then the received CDNI Logging
         File is to be considered non-corrupted.  If the two values are
         different, the received CDNI Logging File is to be considered
         corrupted.  The behavior of the entity that received a
         corrupted CDNI Logging File is outside the scope of this
         specification; we note that the entity MAY attempt to pull the
         same CDNI Logging File from the transmitting entity again.  If
         the entity receiving a non-corrupted CDNI Logging File adds an
         established-origin directive, it MUST then recompute and update
         the SHA256-hash directive so that it also protects the added
         established-origin directive.

      *  Occurrence: There MUST be zero or exactly one instance of this
         directive.  There SHOULD be exactly one instance of this
         directive.  One situation where that directive could be omitted
         is where integrity protection is already provided via another
         mechanism (for example, if an integrity hash is associated to
         the CDNI Logging File out of band through the CDNI Logging Feed
         (Section 4.1) leveraging ATOM extensions such as those proposed
         in [ATOMPUB].  When present, the SHA256-hash field MUST be the
         last line of the CDNI Logging File.

      *  Example: "SHA256-hash: HTAB 64HEXDIG".

   A uCDN-side implementation of the CDNI Logging interface MUST ignore
   a CDNI Logging File that does not comply with the occurrences
   specified above for each and every directive.  For example, a uCDN-



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   side implementation of the CDNI Logging interface receiving a CDNI
   Logging File with zero occurrence of the version directive, or with
   two occurrences of the SHA256-hash, MUST ignore this CDNI Logging
   File.

   An entity receiving a CDNI Logging File with a value set to
   "cdni/1.0" MUST process the CDNI Logging File as per the present
   document.  An entity receiving a CDNI Logging File with a value set
   to a different value MUST process the CDNI Logging File as per the
   specification referenced in the "CDNI Logging File version" registry
   (see Section 6.1) if the implementation supports this specification
   and MUST ignore the CDNI Logging File otherwise.

3.4.  CDNI Logging Records

   A CDNI Logging Record consists of a sequence of CDNI Logging fields
   relating to that single CDNI Logging Record.

   CDNI Logging fields MUST be separated by the horizontal tabulation
   (HTAB) character.

   To facilitate readability, a prefix scheme is used for CDNI Logging
   field names in a similar way to the one used in W3C Extended Log File
   Format [ELF].  The semantics of the prefix in the present document
   are:

   o  "c-" refers to the User Agent that issues the request (corresponds
      to the "client" of W3C Extended Log Format)

   o  "d-" refers to the dCDN (relative to a given CDN acting as an
      uCDN)

   o  "s-" refers to the dCDN Surrogate that serves the request
      (corresponds to the "server" of the W3C Extended Log Format)

   o  "u-" refers to the uCDN (relative to a given CDN acting as a dCDN)

   o  "cs-" refers to communication from the User Agent towards the dCDN
      Surrogate

   o  "sc-" refers to communication from the dCDN Surrogate towards the
      User Agent

   An implementation of the CDNI Logging interface as per the present
   specification MUST support the CDNI HTTP Request Logging Record as
   specified in Section 3.4.1.





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   A CDNI Logging Record contains the corresponding values for the
   fields that are enumerated in the last fields directive before the
   current log line.  Note that the order in which the field values
   appear is dictated by the order of the fields names in the fields
   directive.  There SHOULD be no dependency between the various fields
   values.

3.4.1.  HTTP Request Logging Record

   This section defines the CDNI Logging Record of record-type
   "cdni_http_request_v1".  It is applicable to content delivery
   performed by the dCDN using HTTP/1.0 ([RFC1945]), HTTP/1.1 ([RFC7230]
   [RFC7231] [RFC7232] [RFC7233] [RFC7234] [RFC7235]), or HTTPS
   ([RFC2818] [RFC7230]).  We observe that, in the case of HTTPS
   delivery, there may be value in logging additional information
   specific to the operation of HTTP over Transport Layer Security (TLS)
   and we note that this is outside the scope of the present document
   and may be addressed in a future document defining another CDNI
   Logging Record or another version of the HTTP Request Logging Record.

   The "cdni_http_request_v1" record-type is also expected to be
   applicable to HTTP/2 [RFC7540] since a fundamental design tenet of
   HTTP/2 is to preserve the HTTP/1.1 semantics.  We observe that, in
   the case of HTTP/2 delivery, there may be value in logging additional
   information specific to the additional functionality of HTTP/2 (e.g.,
   information related to connection identification, to stream
   identification, to stream priority, and to flow control).  We note
   that such additional information is outside the scope of the present
   document and may be addressed in a future document defining another
   CDNI Logging Record or another version of the HTTP Request Logging
   Record.

   The "cdni_http_request_v1" record-type contains the following CDNI
   Logging fields, listed by their field name:

   o  Date:

      *  Format: DATE

      *  Field value: The date on which the processing of the request
         completed on the Surrogate.

      *  Occurrence: There MUST be one and only one instance of this
         field.







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   o  Time:

      *  Format: TIME

      *  Field value: The time, which MUST be expressed in Coordinated
         Universal Time (UTC), at which the processing of the request
         completed on the Surrogate.

      *  Occurrence: There MUST be one and only one instance of this
         field.

   o  Time-taken:

      *  Format: DEC

      *  Field value: Decimal value of the duration, in seconds, between
         the start of the processing of the request and the completion
         of the request processing (e.g., completion of delivery) by the
         Surrogate.

      *  Occurrence: There MUST be one and only one instance of this
         field.

   o  c-groupid:

      *  Format: NHTABSTRING

      *  Field value: An opaque identifier for an aggregate set of
         clients, derived from the client IPv4 or IPv6 address in the
         request received by the Surrogate and/or other network-level
         identifying information.  The c-groupid serves to group clients
         into aggregates.  Example aggregates include civil geolocation
         information (the country, second-level administrative division,
         or postal code from which the client is presumed to make the
         request based on a geolocation database lookup) or network
         topological information (e.g., the BGP autonomous system (AS)
         number announcing the prefix containing the address).  The
         c-groupid MAY be structured, e.g., US/TN/MEM/38138.  Agreement
         between the dCDN and the uCDN on a mapping between IPv4 and
         IPv6 addresses and aggregates is presumed to occur out of band.
         The aggregation mapping SHOULD be chosen such that each
         aggregate contains more than one client.

         +  When the aggregate is chosen so that it contains a single
            client (e.g., to allow more detailed analytics, or to allow
            a posteriori analysis of individual delivery, for example,
            in situations of performance-based penalties), the c-groupid
            MAY be structured where some elements identify aggregates



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            and one element identifies the client, e.g.,
            US/TN/MEM/38138/43a5bdd6-95c4-4d62-be65-7410df0021e2.  In
            the case where the aggregate is chosen so that it contains a
            single client:

            -  The element identifying the client SHOULD be
               algorithmically generated (from the client IPv4 or IPv6
               address in the request received by the Surrogate and/or
               other network-level identifying information) in a way
               that SHOULD NOT be linkable back to the global addressing
               context and that SHOULD vary over time (to offer
               protection against long-term attacks).

            -  It is RECOMMENDED that the mapping varies at least once
               every 24 hours.

            -  The algorithmic mapping and variation over time can, in
               some cases, allow the uCDN (with the knowledge of the
               algorithm, the time variation, and the associated
               attributes and keys) to reconstruct the actual client
               IPv4 or IPv6 address and/or other network-level
               identifying information when required (e.g., to allow a
               posteriori analysis of individual delivery, for example,
               in situations of performance-based penalties).  However,
               these end-user addresses SHOULD only be reconstructed on-
               demand and the CDNI Logging File SHOULD only be stored
               with the anonymized c-groupid value.

            -  Allowing reconstruction of client address information
               carries with it grave risks to end-user privacy.  Since
               the c-groupid is, in this case, equivalent in
               identification power to a client IP address, its use may
               be restricted by regulation or law as personally
               identifiable information.  For this reason, such use is
               NOT RECOMMENDED.

            -  One method for mapping that MAY be supported by
               implementations relies on a symmetric key that is known
               only to the uCDN, the dCDN, and the HMAC-based Extract-
               and-Expand Key Derivation Function (HKDF) key derivation
               ([RFC5869]), as will be used in TLS 1.3 ([TLS-1.3]).
               When that method is used:

               o  The uCDN and dCDN need to agree on the "salt" and
                  "input keying material", as described in Section 2.2
                  of [RFC5869] and the initial "info" parameter (which
                  could be something like the business names of the two
                  organizations in UTF-8, concatenated), as described in



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                  Section 2.3 of [RFC5869].  The hash SHOULD be either
                  SHA-2 or SHA-3 [SHA-3], and the encryption algorithm
                  SHOULD be 128-bit AES [AES] in Galois Counter Mode
                  (GCM) [GCM] (AES-GCM) or better.  The pseudorandom key
                  (PRK) SHOULD be chosen by both parties contributing
                  alternate random bytes until sufficient length exists.
                  After the initial setup, client-information can be
                  encrypted using the key generated by the "expand" step
                  of Section 2.3 of [RFC5869].  The encrypted value
                  SHOULD be hex encoded or base64 encoded (as specified
                  in Section 4 of [RFC4648]).  At the agreed-upon
                  expiration time, a new key SHOULD be generated and
                  used.  New keys SHOULD be indicated by prefixing the
                  key with a special character such as an exclamation
                  point.  In this way, shorter lifetimes can be used as
                  needed.

      *  Occurrence: There MUST be one and only one instance of this
         field.

   o  s-ip:

      *  Format: ADDRESS

      *  Field value: The IPv4 or IPv6 address of the Surrogate that
         served the request (i.e., the "server" address).

      *  Occurrence: There MUST be zero or exactly one instance of this
         field.

   o  s-hostname:

      *  Format: Host

      *  Field value: The hostname of the Surrogate that served the
         request (i.e., the "server" hostname).

      *  Occurrence: There MUST be zero or exactly one instance of this
         field.

   o  s-port:

      *  Format: 1*DIGIT

      *  Field value: The destination TCP port (i.e., the "server" port)
         in the request received by the Surrogate.





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      *  Occurrence: There MUST be zero or exactly one instance of this
         field.

   o  cs-method:

      *  Format: NHTABSTRING

      *  Field value: This is the method of the request received by the
         Surrogate.  In the case of HTTP delivery, this is the HTTP
         method in the request.

      *  Occurrence: There MUST be one and only one instance of this
         field.

   o  cs-uri:

      *  Format: NHTABSTRING

      *  Field value: This is the "effective request URI" of the request
         received by the Surrogate as specified in [RFC7230].  It
         complies with the "http" URI scheme or the "https" URI scheme
         as specified in [RFC7230].  Note that cs-uri can be privacy
         sensitive.  In that case, and where appropriate, u-uri could be
         used instead of cs-uri.

      *  Occurrence: There MUST be zero or exactly one instance of this
         field.

   o  u-uri:

      *  Format: NHTABSTRING

      *  Field value: This is a complete URI, derived from the
         "effective request URI" ([RFC7230]) of the request received by
         the Surrogate (i.e., the cs-uri) but transformed by the entity
         generating or transmitting the CDNI Logging Record, in a way
         that is agreed upon between the two ends of the CDNI Logging
         interface, so the transformed URI is meaningful to the uCDN.
         For example, the two ends of the CDNI Logging interface could
         agree that the u-uri is constructed from the cs-uri by removing
         the part of the hostname that exposes which individual
         Surrogate actually performed the delivery.  The details of
         modification performed to generate the u-uri, as well as the
         mechanism to agree on these modifications between the two sides
         of the CDNI Logging interface are outside the scope of the
         present document.





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      *  Occurrence: There MUST be one and only one instance of this
         field.

   o  Protocol:

      *  Format: NHTABSTRING

      *  Field value: This is the value of the HTTP-Version field as
         specified in [RFC7230] of the Request-Line of the request
         received by the Surrogate (e.g., "HTTP/1.1").

      *  Occurrence: There MUST be one and only one instance of this
         field.

   o  sc-status:

      *  Format: 3DIGIT

      *  Field value: This is the Status-Code in the response from the
         Surrogate.  In the case of HTTP delivery, this is the HTTP
         Status-Code in the HTTP response.

      *  Occurrence: There MUST be one and only one instance of this
         field.

   o  sc-total-bytes:

      *  Format: 1*DIGIT

      *  Field value: This is the total number of bytes of the response
         sent by the Surrogate in response to the request.  In the case
         of HTTP delivery, this includes the bytes of the Status-Line,
         the bytes of the HTTP headers, and the bytes of the message-
         body.

      *  Occurrence: There MUST be one, and only one, instance of this
         field.

   o  sc-entity-bytes:

      *  Format: 1*DIGIT

      *  Field value: This is the number of bytes of the message-body in
         the HTTP response sent by the Surrogate in response to the
         request.  This does not include the bytes of the Status-Line or
         the bytes of the HTTP headers.





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      *  Occurrence: There MUST be zero or exactly one instance of this
         field.

   o  cs(insert_HTTP_header_name_here):

      *  Format: QSTRING

      *  Field value: The value of the HTTP header (identified by the
         insert_HTTP_header_name_here in the CDNI Logging field name) as
         it appears in the request processed by the Surrogate, but
         prepended by a DQUOTE and appended by a DQUOTE.  For example,
         when the CDNI Logging field name (FIENAME) listed in the
         preceding fields directive is cs(User-Agent), this CDNI Logging
         field value contains the value of the User-Agent HTTP header as
         received by the Surrogate in the request it processed, but
         prepended by a DQUOTE and appended by a DQUOTE.  If the HTTP
         header, as it appeared in the request processed by the
         Surrogate, contains one or more DQUOTE, each DQUOTE MUST be
         escaped with percent encoding.  For example, if the HTTP header
         contains My_Header"value", then the field value of the
         cs(insert_HTTP_header_name_here) is "My_Header%x22value%x22".
         The entity transmitting the CDNI Logging File MUST ensure that
         the respective insert_HTTP_header_name_here of the
         cs(insert_HTTP_header_name_here) listed in the fields directive
         comply with HTTP specifications.  In particular, this field
         name does not include any HTAB, since this would prevent proper
         parsing of the fields directive by the entity receiving the
         CDNI Logging File.

      *  Occurrence: There MAY be zero, one, or any number of instance
         of this field.

   o  sc(insert_HTTP_header_name_here):

      *  Format: QSTRING

      *  Field value: The value of the HTTP header (identified by the
         insert_HTTP_header_name_here in the CDNI Logging field name) as
         it appears in the response issued by the Surrogate to serve the
         request, but prepended by a DQUOTE and appended by a DQUOTE.
         If the HTTP header, as it appeared in the request processed by
         the Surrogate, contains one or more DQUOTEs, each DQUOTE MUST
         be escaped with percent encoding.  For example, if the HTTP
         header contains My_Header"value", then the field value of the
         sc(insert_HTTP_header_name_here) is "My_Header%x22value%x22".
         The entity transmitting the CDNI Logging File MUST ensure that
         the respective insert_HTTP_header_name_here of the
         cs(insert_HTTP_header_name_here) listed in the fields directive



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         comply with HTTP specifications.  In particular, this field
         name does not include any HTAB, since this would prevent proper
         parsing of the fields directive by the entity receiving the
         CDNI Logging File.

      *  Occurrence: There MAY be zero, one, or any number of instances
         of this field.  For a given insert_HTTP_header_name_here, there
         MUST be zero or exactly one instance of this field.

   o  s-ccid:

      *  Format: QSTRING

      *  Field value: This contains the value of the Content Collection
         IDentifier (CCID) associated by the uCDN to the content served
         by the Surrogate via the CDNI Metadata interface ([CDNI-META]),
         prepended by a DQUOTE and appended by a DQUOTE.  If the CCID
         conveyed in the CDNI Metadata interface contains one or more
         DQUOTEs, each DQUOTE MUST be escaped with percent encoding.
         For example, if the CCID conveyed in the CDNI Metadata
         interface is My_CCIDD"value", then the field value of the
         s-ccid is "My_CCID%x22value%X22".

      *  Occurrence: There MUST be zero or exactly one instance of this
         field.  For a given insert_HTTP_header_name_here, there MUST be
         zero or exactly one instance of this field.

   o  s-sid:

      *  Format: QSTRING

      *  Field value: This contains the value of a Session IDentifier
         (SID) generated by the dCDN for a specific HTTP session,
         prepended by a DQUOTE and appended by a DQUOTE.  In particular,
         for an HTTP Adaptive Streaming (HAS) session, the SID value is
         included in the Logging Record for every content chunk delivery
         of that session in view of facilitating the later correlation
         of all the per-content chunk log records of a given HAS
         session.  See Section 3.4.2.2. of [RFC6983] for more discussion
         on the concept of Session IDentifier in the context of HAS.  If
         the SID conveyed contains one or more DQUOTEs, each DQUOTE MUST
         be escaped with percent-encoding.  For example, if the SID is
         My_SID"value", then the field value of the s-sid is
         "My_SID%x22value%x22".

      *  Occurrence: There MUST be zero or exactly one instance of this
         field.




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   o  s-cached:

      *  Format: 1DIGIT

      *  Field value: This characterizes whether or not the Surrogate
         served the request using content already stored on its local
         cache.  The allowed values are "0" (for miss) and "1" (for
         hit). "1" MUST be used when the Surrogate did serve the request
         exclusively using content already stored on its local cache.
         "0" MUST be used otherwise (including cases where the Surrogate
         served the request using some, but not all, content already
         stored on its local cache).  Note that a "0" only means a cache
         miss in the Surrogate and does not provide any information on
         whether or not the content was already stored in another device
         of the dCDN, i.e., whether this was a "dCDN hit" or a "dCDN
         miss".

      *  Occurrence: There MUST be zero or exactly one instance of this
         field.

   CDNI Logging field names are case-insensitive as per the basic ABNF
   ([RFC5234]).  The "fields" directive corresponding to an HTTP Request
   Logging Record MUST contain all the fields names whose occurrence is
   specified above as "[t]here MUST be one and only one instance of this
   field."  The corresponding fields value MUST be present in every HTTP
   Request Logging Record.

   The "fields" directive corresponding to an HTTP Request Logging
   Record MAY list all the fields values whose occurrence is specified
   above as "[t]here MUST be zero or exactly one instance of this field"
   or "[t]here MAY be zero, one, or any number of instances of this
   field."  The set of such field names actually listed in the "fields"
   directive is selected by the CDN generating the CDNI Logging File
   based on agreements between the interconnected CDNs established
   through mechanisms outside the scope of this specification (e.g.,
   contractual agreements).  When such a field name is not listed in the
   "fields" directive, the corresponding field value MUST NOT be
   included in the Logging Record.  When such a field name is listed in
   the "fields" directive, the corresponding field value MUST be
   included in the Logging Record; if the value for the field is not
   available, this MUST be conveyed via a dash character ("-").

   The fields names listed in the "fields" directive MAY be listed in
   the order in which they are listed in Section 3.4.1 or MAY be listed
   in any other order.






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   Logging some specific fields from HTTP requests and responses can
   introduce serious security and privacy risks.  For example, cookies
   will often contain (months) long-lived token values that can be used
   to log into a service as the relevant user.  Similar values may be
   included in other header fields or within URLs or elsewhere in HTTP
   requests and responses.  Centralizing such values in a CDNI Logging
   File can therefore represent a significant increase in risk both for
   the user and the web service provider, but also for the CDNs
   involved.  Therefore, implementations ought to attempt to lower the
   probability of such bad outcomes, e.g., by only allowing a configured
   set of headers to be added to CDNI Logging Records, or by not
   supporting wildcard selection of HTTP request/response fields to add.
   Such mechanisms can reduce the probability that security (or privacy)
   sensitive values are centralized in CDNI Logging Files.  Also, when
   agreeing on which HTTP request/response fields are to be provided in
   CDNI Logging Files, the uCDN and dCDN administrators ought to
   consider these risks.  Furthermore, CDNs making use of c-groupid to
   identify an aggregate of clients rather than individual clients ought
   to realize that, by logging certain header fields, they may create
   the possibility to re-identify individual clients.  In these cases,
   heeding the above advice, or not logging header fields at all, is
   particularly important if the goal is to provide logs that do not
   identify individual clients.

   A dCDN-side implementation of the CDNI Logging interface MUST
   implement all the following Logging fields in a CDNI Logging Record
   of record-type "cdni_http_request_v1" and MUST support the ability to
   include valid values for each of them:

   o  date

   o  time

   o  time-taken

   o  c-groupid

   o  s-ip

   o  s-hostname

   o  s-port

   o  cs-method

   o  cs-uri

   o  u-uri



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   o  protocol

   o  sc-status

   o  sc-total-bytes

   o  sc-entity-bytes

   o  cs(insert_HTTP_header_name_here)

   o  sc(insert_HTTP_header_name_here)

   o  s-cached

   A dCDN-side implementation of the CDNI Logging interface MAY support
   the following Logging fields in a CDNI Logging Record of record-type
   "cdni_http_request_v1":

   o  s-ccid

   o  s-sid

   If a dCDN-side implementation of the CDNI Logging interface supports
   these fields, it MUST support the ability to include valid values for
   them.

   An uCDN-side implementation of the CDNI Logging interface MUST be
   able to accept CDNI Logging Files with CDNI Logging Records of
   record-type "cdni_http_request_v1" containing any CDNI Logging Field
   defined in Section 3.4.1 as long as the CDNI Logging Record and the
   CDNI Logging File are compliant with the present document.

   In case an uCDN-side implementation of the CDNI Logging interface
   receives a CDNI Logging File with HTTP Request Logging Records that
   do not contain field values for exactly the set of field names
   actually listed in the preceding "fields" directive, the
   implementation MUST ignore those HTTP Request Logging Records and
   MUST accept the other HTTP Request Logging Records.

   To ensure that the Logging File is correct, the text MUST be
   sanitized before being logged.  Null, bare CR, bare LF, and HTAB have
   to be removed by escaping them through percent encoding to avoid
   confusion with the Logging Record separators.








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3.5.  CDNI Logging File Extension

   The CDNI Logging File contains blocks of directives and blocks of
   corresponding records.  The supported set of directives is defined
   relative to the CDNI Logging File Format version.  The complete set
   of directives for version "cdni/1.0" are defined in Section 3.3.  The
   directive list is not expected to require much extension, but when it
   does, the new directive MUST be defined and registered in the "CDNI
   Logging Directive Names" registry, as described in Figure 9, and a
   new version MUST be defined and registered in the "CDNI Logging File
   version" registry, as described in Section 6.2.  For example, adding
   a new CDNI Logging Directive, e.g., "foo", to the set of directives
   defined for "cdni/1.0" in Section 3.3, would require registering both
   the new CDNI Logging Directive "foo" and a new CDNI Logging File
   version, e.g., "CDNI/2.0", which includes all of the existing CDNI
   Logging Directives of "cdni/1.0" plus "foo".

   It is expected that as new logging requirements arise, the list of
   fields to log will change and expand.  When adding new fields, the
   new fields MUST be defined and registered in the "CDNI Logging Field
   Names" registry, as described in Section 6.4, and a new record-type
   MUST be defined and registered in the "CDNI Logging record-types"
   registry, as described in Section 6.3.  For example, adding a new
   CDNI Logging Field, e.g., "c-bar", to the set of fields defined for
   "cdni_http_request_v1" in Section 3.4.1, would require registering
   both the new CDNI Logging Field "c-bar" and a new CDNI record-type,
   e.g., "cdni_http_request_v2", which includes all of the existing CDNI
   Logging Fields of "cdni_http_request_v1" plus "c-bar".

3.6.  CDNI Logging File Examples

   Let us consider the upstream CDN and the downstream CDN-labeled uCDN
   and dCDN-1 in Figure 1.  When dCDN-1 acts as a downstream CDN for
   uCDN and performs content delivery on behalf of uCDN, dCDN-1 will
   include the CDNI Logging Records corresponding to the content
   deliveries performed on behalf of uCDN in the CDNI Logging Files for
   uCDN.  An example CDNI Logging File communicated by dCDN-1 to uCDN is
   shown below in Figure 4.













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   #version:<HTAB>cdni/1.0<CRLF>

   #UUID:<HTAB>urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6<CRLF>

   #claimed-origin:<HTAB>cdni-logging-entity.dcdn-1.example.com<CRLF>

   #record-type:<HTAB>cdni_http_request_v1<CRLF>

   #fields:<HTAB>date<HTAB>time<HTAB>time-taken<HTAB>c-groupid<HTAB>
   cs-method<HTAB>u-uri<HTAB>protocol<HTAB>
   sc-status<HTAB>sc-total-bytes<HTAB>cs(User-Agent)<HTAB>
   cs(Referer)<HTAB>s-cached<CRLF>

   2013-05-17<HTAB>00:38:06.825<HTAB>9.058<HTAB>US/TN/MEM/38138<HTAB>
   GET<HTAB>
   http://cdni-ucdn.dcdn-1.example.com/video/movie100.mp4<HTAB>
   HTTP/1.1<HTAB>200<HTAB>6729891<HTAB>"Mozilla/5.0
   (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
   Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
   "host1.example.com"<HTAB>1<CRLF>

   2013-05-17<HTAB>00:39:09.145<HTAB>15.32<HTAB>FR/PACA/NCE/06100<HTAB>
   GET<HTAB>
   http://cdni-ucdn.dcdn-1.example.com/video/movie118.mp4<HTAB>
   HTTP/1.1<HTAB>200<HTAB>15799210<HTAB>"Mozilla/5.0
   (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
   Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
   "host1.example.com"<HTAB>1<CRLF>

   2013-05-17<HTAB>00:42:53.437<HTAB>52.879<HTAB>US/TN/MEM/38138<HTAB>
   GET<HTAB>
   http://cdni-ucdn.dcdn-1.example.com/video/picture11.mp4<HTAB>
   HTTP/1.0<HTAB>200<HTAB>97234724<HTAB>"Mozilla/5.0
   (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
   Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
   "host5.example.com"<HTAB>0<CRLF>

   #SHA256-hash:<HTAB> 64-hexadecimal-digit hash value <CRLF>

                    Figure 4: CDNI Logging File Example

   If uCDN establishes, by some means (e.g., via TLS authentication when
   pulling the CDNI Logging File), the identity of the entity from which
   it pulled the CDNI Logging File, uCDN can add an established-origin
   directive to the CDNI Logging as illustrated below:

  #established-origin:<HTAB>cdni-logging-entity.dcdn-1.example.com<CRLF>




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   As illustrated in Figure 2, uCDN will then ingest the corresponding
   CDNI Logging Records into its Collection process, alongside the
   Logging Records generated locally by the uCDN itself.  This allows
   uCDN to aggregate Logging Records for deliveries performed by itself
   (through Records generated locally) as well as for deliveries
   performed by its downstream CDN(s).  This aggregate information can
   then be used (after Filtering and Rectification, as illustrated in
   Figure 2) by log-consuming applications that take into account
   deliveries performed by uCDN as well as by all of its downstream
   CDNs.

   We observe that the time between

   1.  when a delivery is completed in dCDN and

   2.  when the corresponding Logging Record is ingested by the
       Collection process in uCDN

   depends on a number of parameters such as the Logging Period agreed
   to by uCDN and dCDN, how much time uCDN waits before pulling the CDNI
   Logging File once it is advertised in the CDNI Logging Feed, and the
   time to complete the pull of the CDNI Logging File.  Therefore, if we
   consider the set of Logging Records aggregated by the Collection
   process in uCDN in a given time interval, there could be a permanent
   significant timing difference between the CDNI Logging Records
   received from the dCDN and the Logging Records generated locally.
   For example, in a given time interval, the Collection process in uCDN
   may be aggregating Logging Records generated locally by uCDN for
   deliveries performed in the last hour and CDNI Logging Records
   generated in the dCDN for deliveries in the hour before last.

   Say that, for some reason (for example, a Surrogate bug), dCDN-1
   could not collect the total number of bytes of the responses sent by
   the Surrogate (in other words, the value for sc-total-bytes is not
   available).  Then the corresponding CDNI Logging Records would
   contain a dash character ("-") in lieu of the value for the sc-total-
   bytes field (as specified in Section 3.4.1).  In that case, the CDNI
   Logging File that would be communicated by dCDN-1 to uCDN is shown
   below in Figure 5.












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   #version:<HTAB>cdni/1.0<CRLF>

   #UUID:<HTAB>urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6<CRLF>

   #claimed-origin:<HTAB>cdni-logging-entity.dcdn-1.example.com<CRLF>

   #record-type:<HTAB>cdni_http_request_v1<CRLF>

   #fields:<HTAB>date<HTAB>time<HTAB>time-taken<HTAB>c-groupid<HTAB>
   cs-method<HTAB>u-uri<HTAB>protocol<HTAB>
   sc-status<HTAB>sc-total-bytes<HTAB>cs(User-Agent)<HTAB>
   cs(Referer)<HTAB>s-cached<CRLF>

   2013-05-17<HTAB>00:38:06.825<HTAB>9.058<HTAB>US/TN/MEM/38138<HTAB>
   GET<HTAB>
   http://cdni-ucdn.dcdn-1.example.com/video/movie100.mp4<HTAB>
   HTTP/1.1<HTAB>200<HTAB>-<HTAB>"Mozilla/5.0
   (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
   Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
   "host1.example.com"<HTAB>1<CRLF>

   2013-05-17<HTAB>00:39:09.145<HTAB>15.32<HTAB>FR/PACA/NCE/06100<HTAB>
   GET<HTAB>
   http://cdni-ucdn.dcdn-1.example.com/video/movie118.mp4<HTAB>
   HTTP/1.1<HTAB>200<HTAB>-<HTAB>"Mozilla/5.0
   (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
   Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
   "host1.example.com"<HTAB>1<CRLF>

   2013-05-17<HTAB>00:42:53.437<HTAB>52.879<HTAB>US/TN/MEM/38138<HTAB>
   GET<HTAB>
   http://cdni-ucdn.dcdn-1.example.com/video/picture11.mp4<HTAB>
   HTTP/1.0<HTAB>200<HTAB>-<HTAB>"Mozilla/5.0
   (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
   Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
   "host5.example.com"<HTAB>0<CRLF>

   #SHA256-hash:<HTAB> 64-hexadecimal-digit hash value <CRLF>

      Figure 5: CDNI Logging File Example with a Missing Field Value











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3.7.  Cascaded CDNI Logging Files Example

   Let us consider the cascaded CDN scenario of uCDN, dCDN-2, and dCDN-3
   as depicted in Figure 1.  After completion of a delivery by dCDN-3 on
   behalf of dCDN-2, dCDN-3 will include a corresponding Logging Record
   in a CDNI Logging File that will be pulled by dCDN-2 and that is
   illustrated below in Figure 6.  In practice, a CDNI Logging File is
   likely to contain a very high number of CDNI Logging Records.
   However, for readability, the example in Figure 6 contains a single
   CDNI Logging Record.

   #version:<HTAB>cdni/1.0<CRLF>

   #UUID:<HTAB>urn:uuid:65718ef-0123-9876-adce4321bcde<CRLF>

   #claimed-origin:<HTAB>cdni-logging-entity.dcdn-3.example.com<CRLF>

   #record-type:<HTAB>cdni_http_request_v1<CRLF>

   #fields:<HTAB>date<HTAB>time<HTAB>time-taken<HTAB>c-groupid<HTAB>
   cs-method<HTAB>u-uri<HTAB>protocol<HTAB>
   sc-status<HTAB>sc-total-bytes<HTAB>cs(User-Agent)<HTAB>
   cs(Referer)<HTAB>s-cached<CRLF>

   2013-05-17<HTAB>00:39:09.119<HTAB>14.07<HTAB>US/CA/SFO/94114<HTAB>
   GET<HTAB>
   http://cdni-dcdn-2.dcdn-3.example.com/video/movie118.mp4<HTAB>
   HTTP/1.1<HTAB>200<HTAB>15799210<HTAB>"Mozilla/5.0
   (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
   Gecko) Chrome/5.0.375.127 Safari /533.4"<HTAB>
   "host1.example.com"<HTAB>1<CRLF>

   #SHA256-hash:<HTAB> 64-hexadecimal-digit hash value <CRLF>

      Figure 6: Cascaded CDNI Logging File Example (dCDN-3 to dCDN-2)

   If dCDN-2 establishes, by some means (e.g., via TLS authentication
   when pulling the CDNI Logging File), the identity of the entity from
   which it pulled the CDNI Logging File, dCDN-2 can add an established-
   origin directive to the CDNI Logging as illustrated below:

  #established-origin:<HTAB>cdni-logging-entity.dcdn-3.example.com<CRLF>

   dCDN-2 (behaving as an upstream CDN from the viewpoint of dCDN-3)
   will then ingest the CDNI Logging Record for the considered dCDN-3
   delivery into its Collection process (as illustrated in Figure 2).
   This Logging Record may be aggregated with Logging Records generated
   locally by dCDN-2 for deliveries performed by dCDN-2 itself.  Say,



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   for illustration, that the content delivery performed by dCDN-3 on
   behalf of dCDN-2 had actually been redirected to dCDN-2 by uCDN, and
   say that another content delivery has just been redirected by uCDN to
   dCDN-2 and that dCDN-2 elected to perform the corresponding delivery
   itself.  Then, after Filtering and Rectification (as illustrated in
   Figure 2), dCDN-2 will include the two Logging Records corresponding
   respectively to the delivery performed by dCDN-3 and the delivery
   performed by dCDN-2, in the next CDNI Logging File that will be
   communicated to uCDN.  An example of such a CDNI Logging File is
   illustrated below in Figure 7.

   #version:<HTAB>cdni/1.0<CRLF>

   #UUID:<HTAB>urn:uuid:1234567-8fedc-abab-0987654321ff<CRLF>

   #claimed-origin:<HTAB>cdni-logging-entity.dcdn-2.example.com<CRLF>

   #record-type:<HTAB>cdni_http_request_v1<CRLF>

   #fields:<HTAB>date<HTAB>time<HTAB>time-taken<HTAB>c-groupid<HTAB>
   cs-method<HTAB>u-uri<HTAB>protocol<HTAB>
   sc-status<HTAB>sc-total-bytes<HTAB>cs(User-Agent)<HTAB>
   cs(Referer)<HTAB>s-cached<CRLF>

   2013-05-17<HTAB>00:39:09.119<HTAB>14.07<HTAB>US/CA/SFO/94114<HTAB>
   GET<HTAB>
   http://cdni-ucdn.dcdn-2.example.com/video/movie118.mp4<HTAB>
   HTTP/1.1<HTAB>200<HTAB>15799210<HTAB>"Mozilla/5.0
   (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
   Gecko) Chrome/5.0.375.127 Safari /533.4"<HTAB>
   "host1.example.com"<HTAB>1<CRLF>

   2013-05-17<HTAB>01:42:53.437<HTAB>52.879<HTAB>FR/IDF/PAR/75001<HTAB>
   GET<HTAB>
   http://cdni-ucdn.dcdn-2.example.com/video/picture11.mp4<HTAB>
   HTTP/1.0<HTAB>200<HTAB>97234724<HTAB>"Mozilla/5.0
   (Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
   Gecko) Chrome/5.0.375.127 Safari /533.4"<HTAB>
   "host5.example.com"<HTAB>0<CRLF>

   #SHA256-hash:<HTAB> 64-hexadecimal-digit hash value <CRLF>

       Figure 7: Cascaded CDNI Logging File Example (dCDN-2 to uCDN)








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   If uCDN establishes, by some means (e.g., via TLS authentication when
   pulling the CDNI Logging File), the identity of the entity from which
   it pulled the CDNI Logging File, uCDN can add to the CDNI Logging an
   established-origin directive as illustrated below:

  #established-origin:<HTAB>cdni-logging-entity.dcdn-2.example.com<CRLF>

   In the example of Figure 7, we observe that:

   o  The first Logging Record corresponds to the Logging Record
      communicated earlier to dCDN-2 by dCDN-3, which corresponds to a
      delivery redirected by uCDN to dCDN-2 and then redirected by
      dCDN-2 to dCDN-3.  The fields values in this Logging Record are
      copied from the corresponding CDNI Logging Record communicated to
      dCDN2 by dCDN-3, with the exception of the u-uri that now reflects
      the URI convention between uCDN and dCDN-2 and that presents the
      delivery to uCDN as if it was performed by dCDN-2 itself.  This
      reflects the fact that dCDN-2 had taken full responsibility of the
      corresponding delivery (even if in this case, dCDN-2 elected to
      redirect the delivery to dCDN-3 so it is actually performed by
      dCDN-3 on behalf of dCDN-2).

   o  The second Logging Record corresponds to a delivery redirected by
      uCDN to dCDN-2 and performed by dCDN-2 itself.  The time of the
      delivery in this Logging Record may be significantly more recent
      than the first Logging Record since it was generated locally while
      the first Logging Record was generated by dCDN-3 and had to be
      advertised, and then pulled and then ingested into the dCDN-2
      Collection process, before being aggregated with the second
      Logging Record.

4.  Protocol for Exchange of CDNI Logging File after Full Collection

   This section specifies a protocol for the exchange of CDNI Logging
   Files as specified in Section 3 after the CDNI Logging File is fully
   collected by the dCDN.

   This protocol comprises:

   o  a CDNI Logging feed, allowing the dCDN to notify the uCDN about
      the CDNI Logging Files that can be retrieved by that uCDN from the
      dCDN, as well as all the information necessary for retrieving each
      of these CDNI Logging Files.  The CDNI Logging feed is specified
      in Section 4.1.

   o  a CDNI Logging File pull mechanism, allowing the uCDN to obtain
      from the dCDN a given CDNI Logging File at the uCDN's convenience.
      The CDNI Logging File pull mechanism is specified in Section 4.2.



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   An implementation of the CDNI Logging interface on the dCDN side (the
   entity generating the CDNI Logging File) MUST support the server side
   of the CDNI Logging feed (as specified in Section 4.1) and the server
   side of the CDNI Logging pull mechanism (as specified in
   Section 4.2).

   An implementation of the CDNI Logging interface on the uCDN side (the
   entity consuming the CDNI Logging File) MUST support the client side
   of the CDNI Logging feed (as specified in Section 4.1) and the client
   side of the CDNI Logging pull mechanism (as specified in
   Section 4.2).

4.1.  CDNI Logging Feed

   The server-side implementation of the CDNI Logging feed MUST produce
   an Atom feed [RFC4287].  This feed is used to advertise log files
   that are available for the client-side to retrieve using the CDNI
   Logging pull mechanism.

4.1.1.  Atom Formatting

   A CDNI Logging feed MUST be structured as an Archived feed, as
   defined in [RFC5005], and MUST be formatted in Atom [RFC4287].  This
   means it consists of a subscription document that is regularly
   updated as new CDNI Logging Files become available, and information
   about older CDNI Logging Files is moved into archive documents.  Once
   created, archive documents are never modified.

   Each CDNI Logging File listed in an Atom feed MUST be described in an
   atom:entry container element.

   The atom:entry MUST contain an atom:content element whose "src"
   attribute is a link to the CDNI Logging File and whose "type"
   attribute is the MIME Media Type indicating that the entry is a CDNI
   Logging File.  This MIME Media Type is defined as "application/cdni"
   (See [RFC7736]) with the Payload Type (ptype) parameter set to
   "logging-file".

   For compatibility with some Atom feed readers, the atom:entry MAY
   also contain an atom:link entry whose "href" attribute is a link to
   the CDNI Logging File and whose "type" attribute is the MIME Media
   Type indicating that the entry is a CDNI Logging File using the
   "application/cdni" MIME Media Type with the Payload Type (ptype)
   parameter set to "logging-file" (see [RFC7736]).







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   The URI used in the atom:id of the atom:entry MUST contain the UUID
   of the CDNI Logging File.

   The atom:updated in the atom:entry MUST indicate the time at which
   the CDNI Logging File was last updated.

4.1.2.  Updates to Log Files and the Feed

   CDNI Logging Files MUST NOT be modified by the dCDN once published in
   the CDNI Logging feed.

   The frequency with which the subscription feed is updated, the period
   of time covered by each CDNI Logging File or each archive document,
   and timeliness of publishing of CDNI Logging Files are outside the
   scope of the present document and are expected to be agreed upon by
   uCDN and dCDN via other means (e.g., human agreement).

   The server-side implementation MUST be able to set, and SHOULD set,
   HTTP-cache control headers on the subscription feed to indicate the
   frequency at which the client-side is to poll for updates.

   The client-side MAY use HTTP-cache control headers (set by the
   server-side) on the subscription feed to determine the frequency at
   which to poll for updates.  The client-side MAY instead, or in
   addition, use other information to determine when to poll for updates
   (e.g., a polling frequency that may have been negotiated between the
   uCDN and dCDN by mechanisms outside the scope of the present document
   and that is to override the indications provided in the HTTP-cache
   control headers).

   The potential retention limits (e.g., sliding time window) within
   which the dCDN is to retain and be ready to serve an archive document
   is outside the scope of the present document and is expected to be
   agreed upon by uCDN and dCDN via other means (e.g., human agreement).
   The server-side implementation MUST retain, and be ready to serve,
   any archive document within the agreed retention limits.  Outside
   these agreed limits, the server-side implementation MAY indicate its
   inability to serve (e.g., with HTTP status code 404) an archive
   document or MAY refuse to serve it (e.g., with HTTP status code 403
   or 410).











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4.1.3.  Redundant Feeds

   The server-side implementation MAY present more than one CDNI Logging
   feed for redundancy.  Each CDNI Logging File MAY be published in more
   than one feed.

   A client-side implementation MAY support such redundant CDNI Logging
   feeds.  If it supports a redundant CDNI Logging feed, the client-side
   can use the UUID of the CDNI Logging File, presented in the atom:id
   element of the Atom feed, to avoid unnecessarily pulling and storing
   a given CDNI Logging File more than once.

4.1.4.  Example CDNI Logging Feed

   Figure 8 illustrates an example of the subscription document of a
   CDNI Logging feed.



































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   <?xml version="1.0" encoding="utf-8"?>
   <feed xmlns="http://www.w3.org/2005/Atom">
     <title type="text">CDNI Logging Feed</title>
     <updated>2013-03-23T14:46:11Z</updated>
     <id>urn:uuid:663ae677-40fb-e99a-049d-c5642916b8ce</id>
     <link href="https://dcdn.example/logfeeds/ucdn1"
        rel="self" type="application/atom+xml" />
     <link href="https://dcdn.example/logfeeds/ucdn1"
        rel="current" type="application/atom+xml" />
     <link href="https://dcdn.example/logfeeds/ucdn1/201303231400"
        rel="prev-archive" type="application/atom+xml" />
     <generator version="example version 1">CDNI Log Feed
        Generator</generator>
     <author><name>dcdn.example</name></author>
     <entry>
       <title type="text">CDNI Logging File for uCDN at
         2013-03-23 14:15:00</title>
         <id>urn:uuid:12345678-1234-abcd-00aa-01234567abcd</id>
         <updated>2013-03-23T14:15:00Z</updated>
         <content src="https://dcdn.example/logs/ucdn/
            http-requests-20130323141500000000"
            type="application/cdni"
            ptype="logging-file"/>
         <summary>CDNI Logging File for uCDN at
         2013-03-23 14:15:00</summary>
     </entry>
     <entry>
       <title type="text">CDNI Logging File for uCDN at
         2013-03-23 14:30:00</title>
         <id>urn:uuid:87654321-4321-dcba-aa00-dcba7654321</id>
         <updated>2013-03-23T14:30:00Z</updated>
         <content src="https://dcdn.example/logs/ucdn/
            http-requests-20130323143000000000"
            type="application/cdni"
            ptype="logging-file"/>
         <summary>CDNI Logging File for uCDN at
         2013-03-23 14:30:00</summary>
     </entry>
     ...
     <entry>
       ...
     </entry>
   </feed>

      Figure 8: Example Subscription Document of a CDNI Logging Feed






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4.2.  CDNI Logging File Pull

   A client-side implementation of the CDNI Logging interface MAY pull,
   at its convenience, a CDNI Logging File that is published by the
   server-side in the CDNI Logging Feed (in the subscription document or
   an archive document).  To do so, the client-side:

   o  MUST implement HTTP/1.1 ([RFC7230] [RFC7231] [RFC7232] [RFC7233]
      [RFC7234] [RFC7235]), MAY also support other HTTP versions (e.g.,
      HTTP/2 [RFC7540]), and MAY negotiate which HTTP version is
      actually used.  This allows operators and implementers to choose
      to use later versions of HTTP to take advantage of new features,
      while still ensuring interoperability with systems that only
      support HTTP/1.1;

   o  MUST use the URI that was associated to the CDNI Logging File
      (within the "src" attribute of the corresponding atom:content
      element) in the CDNI Logging Feed;

   o  MUST support exchange of CDNI Logging Files with no content
      encoding applied to the representation;

   o  MUST support exchange of CDNI Logging Files with "gzip" content
      encoding (as defined in [RFC7230]) applied to the representation.

   Note that a client-side implementation of the CDNI Logging interface
   MAY pull a CDNI Logging File that it has already pulled.

   The server-side implementation MUST respond to a valid pull request
   by a client-side implementation for a CDNI Logging File published by
   the server-side in the CDNI Logging Feed (in the subscription
   document or an archive document).  The server-side implementation:

   o  MUST implement HTTP/1.1 to handle the client-side request and MAY
      also support other HTTP versions (e.g., HTTP/2);

   o  MUST include the CDNI Logging File identified by the request URI
      inside the body of the HTTP response;

   o  MUST support exchange of CDNI Logging Files with no content
      encoding applied to the representation;

   o  MUST support exchange of CDNI Logging Files with "gzip" content
      encoding (as defined in [RFC7231]) applied to the representation.







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   Content negotiation approaches defined in [RFC7231] (e.g., using
   Accept-Encoding request-header field or Content-Encoding entity-
   header field) MAY be used by the client-side and server-side
   implementations to establish the content coding to be used for a
   particular exchange of a CDNI Logging File.

   Applying compression content encoding (such as "gzip") is expected to
   mitigate the impact of exchanging the large volumes of logging
   information expected across CDNs.  This is expected to be
   particularly useful in the presence of HTTP Adaptive Streaming (HAS)
   that, as per the present version of the document, will result in a
   separate CDNI Log Record for each HAS segment delivery in the CDNI
   Logging File.

   The potential retention limits (e.g., sliding time window and maximum
   aggregate file storage quotas) within which the dCDN is to retain and
   be ready to serve a CDNI Logging File previously advertised in the
   CDNI Logging Feed is outside the scope of the present document and is
   expected to be agreed upon by uCDN and dCDN via other means (e.g.,
   human agreement).  The server-side implementation MUST retain, and be
   ready to serve, any CDNI Logging File within the agreed retention
   limits.  Outside these agreed limits, the server-side implementation
   MAY indicate its inability to serve (e.g., with HTTP status code 404)
   a CDNI Logging File or MAY refuse to serve it (e.g., with HTTP status
   code 403 or 410).

5.  Protocol for Exchange of CDNI Logging File During Collection

   We note that, in addition to the CDNI Logging File exchange protocol
   specified in Section 4, implementations of the CDNI Logging interface
   may also support other mechanisms to exchange CDNI Logging Files.  In
   particular, such mechanisms might allow the exchange of the CDNI
   Logging File to start before the file is fully collected.  This can
   allow CDNI Logging Records to be communicated by the dCDN to the uCDN
   as they are gathered by the dCDN without having to wait until all the
   CDNI Logging Records of the same logging period are collected in the
   corresponding CDNI Logging File.  This approach is commonly referred
   to as the "tailing" of the file.

   Such an approach could be used, for example, to exchange logging
   information with a significantly reduced time-lag (e.g., sub-minute
   or sub-second) between when the event occurred in the dCDN and when
   the corresponding CDNI Logging Record is made available to the uCDN.
   This can satisfy log-consuming applications requiring extremely fresh
   logging information such as near-real-time content delivery
   monitoring.  Such mechanisms are for further study and are outside
   the scope of this document.




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6.  IANA Considerations

6.1.  CDNI Logging Directive Names Registry

   IANA has created a new "CDNI Logging Directive Names" subregistry
   under the "Content Delivery Networks Interconnection (CDNI)
   Parameters" registry.

   The initial contents of the "CDNI Logging Directives" registry
   comprise the names of the directives specified in Section 3.3 of the
   present document and are as follows:

     +------------------------------+-----------+
     | Directive Name               | Reference |
     +------------------------------+-----------+
     | version                      | RFC 7937  |
     | UUID                         | RFC 7937  |
     | claimed-origin               | RFC 7937  |
     | established-origin           | RFC 7937  |
     | remark                       | RFC 7937  |
     | record-type                  | RFC 7937  |
     | fields                       | RFC 7937  |
     | SHA256-hash                  | RFC 7937  |
     +------------------------------+-----------+

              Figure 9: CDNI Logging Directive Names Registry

   Within the registry, names are to be allocated by IANA according to
   the "Specification Required" policy specified in [RFC5226].
   Directive names are to be allocated by IANA with a format of
   NAMEFORMAT (see Section 3.1).  All directive names defined in the
   Logging File are case-insensitive as per the basic ABNF ([RFC5234]).

   Each specification that defines a new CDNI Logging directive needs to
   contain a description for the new directive with the same set of
   information as provided in Section 3.3 (i.e., format, directive
   value, and occurrence).

6.2.  CDNI Logging File version Registry

   IANA has created a new "CDNI Logging File version" subregistry under
   the "Content Delivery Networks Interconnection (CDNI) Parameters"
   registry.








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   The initial contents of the "CDNI Logging File version" registry
   comprise the value "cdni/1.0" specified in Section 3.3 of the present
   document and are as follows:

    +-----------------+-----------+----------------------------------+
    | version         | Reference |        Description               |
    +-----------------+-----------+----------------------------------+
    | cdni/1.0        | RFC 7937  | CDNI Logging File version 1.0    |
    |                 |           | as specified in RFC 7937         |
    +-----------------+-----------+----------------------------------+

               Figure 10: CDNI Logging File version Registry

   Within the registry, version values are to be allocated by IANA
   according to the "Specification Required" policy specified in
   [RFC5226].  Version values are to be allocated by IANA with a format
   of NAMEFORMAT (see Section 3.1).  All version values defined in the
   Logging File are case-insensitive as per the basic ABNF ([RFC5234]).

6.3.  CDNI Logging record-types Registry

   IANA has created a new "CDNI Logging record-types" subregistry under
   the "Content Delivery Networks Interconnection (CDNI) Parameters"
   registry.

   The initial contents of the "CDNI Logging record-types" registry
   comprise the names of the CDNI Logging record-types specified in
   Section 3.4 of the present document and are as follows:

  +----------------------+-----------+---------------------------------+
  | record-types         | Reference |        Description              |
  +----------------------+-----------+---------------------------------+
  | cdni_http_request_v1 | RFC 7937  | CDNI Logging Record version 1   |
  |                      |           | for content delivery using HTTP |
  +----------------------+-----------+---------------------------------+

               Figure 11: CDNI Logging record-types Registry

   Within the registry, record-types are to be allocated by IANA
   according to the "Specification Required" policy specified in
   [RFC5226].  Record-types are to be allocated by IANA with a format of
   NAMEFORMAT (see Section 3.1).  All record-types defined in the
   Logging File are case-insensitive as per the basic ABNF ([RFC5234]).








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   Each specification that defines a new record-type needs to contain a
   description for the new record-type with the same set of information
   as provided in Section 3.4.1.  This includes:

   o  A list of all the CDNI Logging fields that can appear in a CDNI
      Logging Record of the new record-type

   o  For all these fields: a specification of the occurrence for each
      Field in the new record-type

   o  For every newly defined Field, i.e., for every Field that results
      in a registration in the "CDNI Logging Field Names" registry
      (Section 6.4): a specification of the field name, format, and
      field value.

6.4.  CDNI Logging Field Names Registry

   IANA has created a new "CDNI Logging Field Names" subregistry under
   the "Content Delivery Networks Interconnection (CDNI) Parameters"
   registry.

   This registry is intended to be shared across the currently defined
   record-type (i.e., cdni_http_request_v1) as well as potentially other
   CDNI Logging record-types that may be defined in separate
   specifications.  When a field from this registry is used by another
   CDNI Logging record-type, it is to be used with the exact semantics
   and format specified in the document that registered this field and
   that is identified in the Reference column of the registry.  If
   another CDNI Logging record-type requires a field with semantics that
   are not strictly identical, or a format that is not strictly
   identical, then this new field is to be registered in the registry
   with a different field name.  When a field from this registry is used
   by another CDNI Logging record-type, it can be used with different
   occurrence rules.

















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   The initial contents of the "CDNI Logging Fields Names" registry
   comprise the names of the CDNI Logging fields specified in
   Section 3.4 of the present document and are as follows:

     +------------------------------------------+-----------+
     | Field Name                               | Reference |
     +------------------------------------------+-----------+
     | date                                     | RFC 7937  |
     | time                                     | RFC 7937  |
     | time-taken                               | RFC 7937  |
     | c-groupid                                | RFC 7937  |
     | s-ip                                     | RFC 7937  |
     | s-hostname                               | RFC 7937  |
     | s-port                                   | RFC 7937  |
     | cs-method                                | RFC 7937  |
     | cs-uri                                   | RFC 7937  |
     | u-uri                                    | RFC 7937  |
     | protocol                                 | RFC 7937  |
     | sc-status                                | RFC 7937  |
     | sc-total-bytes                           | RFC 7937  |
     | sc-entity-bytes                          | RFC 7937  |
     | cs(insert_HTTP_header_name_here)         | RFC 7937  |
     | sc(insert_HTTP_header_name_here)         | RFC 7937  |
     | s-ccid                                   | RFC 7937  |
     | s-sid                                    | RFC 7937  |
     | s-cached                                 | RFC 7937  |
     +------------------------------------------+-----------+

               Figure 12: CDNI Logging Field Names Registry

   Within the registry, names are to be allocated by IANA according to
   the "Specification Required" policy specified in [RFC5226].  Field
   names are to be allocated by IANA with a format of NHTABSTRING (see
   Section 3.1).  All field names defined in the Logging File are case-
   insensitive as per the basic ABNF ([RFC5234]).
















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6.5.  CDNI Logging Payload Type

   IANA has registered the following new Payload Type in the "CDNI
   Payload Types" registry for use with the application/cdni MIME media
   type.

                    +----------------------+---------------+
                    | Payload Type         | Specification |
                    +----------------------+---------------+
                    | logging-file         | RFC 7937]     |
                    +----------------------+---------------+

                   Figure 13: CDNI Logging Payload Type

   The purpose of the logging-file payload type is to distinguish
   between CDNI Logging Files and other CDNI messages.

   o  Interface: LI

   o  Encoding: See Section 3.2, Section 3.3, and Section 3.4

7.  Security Considerations

7.1.  Authentication, Authorization, Confidentiality, and Integrity
      Protection

   An implementation of the CDNI Logging interface MUST support TLS
   transport of the CDNI Logging feed (Section 4.1) and of the CDNI
   Logging File pull (Section 4.2) as per [RFC2818] and [RFC7230].

   TLS MUST be used by the server-side and the client-side of the CDNI
   Logging feed, as well as the server-side and the client-side of the
   CDNI Logging File pull mechanism, including authentication of the
   remote end, unless alternate methods are used for ensuring the
   security of the information exchanged over the LI interface (such as
   setting up an IPsec tunnel between the two CDNs or using a physically
   secured internal network between two CDNs that are owned by the same
   corporate entity).

   The use of TLS for transport of the CDNI Logging feed and CDNI
   Logging File pull allows:

   o  the dCDN and uCDN to authenticate each other using TLS client auth
      and TLS server auth.







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   And, once they have mutually authenticated each other, it allows:

   o  the dCDN and uCDN to authorize each other (to ensure they are
      transmitting/receiving CDNI Logging File to/from an authorized
      CDN).

   o  the CDNI Logging information to be transmitted with
      confidentiality.

   o  the integrity of the CDNI Logging information to be protected
      during the exchange.

   When TLS is used, the general TLS usage guidance in [RFC7525] MUST be
   followed.

   The SHA256-hash directive inside the CDNI Logging File provides
   additional integrity protection, this time targeting potential
   corruption of the CDNI Logging information during the CDNI Logging
   File generation, storage, or exchange.  This mechanism does not
   itself allow restoration of the corrupted CDNI Logging information,
   but it allows detection of such corruption, and therefore triggering
   of appropriate corrective actions (e.g., discard of corrupted
   information, and attempt to re-obtain the CDNI Logging information).
   Note that the SHA256-hash does not protect against tampering by a
   third party, since such a third party could have recomputed and
   updated the SHA256-hash after tampering.  Protection against third-
   party tampering, when the CDNI Logging File is communicated over the
   CDN Logging interface, can be achieved as discussed above through the
   use of TLS.

7.2.  Denial of Service

   This document does not define a specific mechanism to protect against
   Denial-of-Service (DoS) attacks on the Logging interface.  However,
   the CDNI Logging feed and CDNI Logging pull endpoints are typically
   to be accessed only by a very small number of valid remote endpoints,
   and therefore can be easily protected against DoS attacks through the
   usual conventional DoS-protection mechanisms such as firewalling or
   use of Virtual Private Networks (VPNs).

   Protection of dCDN Surrogates against spoofed delivery requests is
   outside the scope of the CDNI Logging interface.









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7.3.  Privacy

   CDNs have the opportunity to collect detailed information about the
   downloads performed by end users.  A dCDN is expected to collect such
   information into CDNI Logging Files, which are then communicated to a
   uCDN.

   Having detailed CDNI Logging information known by the dCDN in itself
   does not represent a particular privacy concern since the dCDN is
   obviously fully aware of all information logged since it generated
   the information in the first place.

   Transporting detailed CDNI Logging information over the HTTP-based
   CDNI Logging interface does not represent a particular privacy
   concern because it is protected by the usual privacy-protection
   mechanism (e.g., TLS).

   When HTTP redirection is used between the uCDN and the dCDN, making
   detailed CDNI Logging information known to the uCDN does not
   represent a particular privacy concern because the uCDN is already
   exposed at request redirection time to most of the information that
   shows up as CDNI Logging information (e.g., end-user IP address, URL,
   and HTTP headers).  When DNS redirection is used between the uCDN and
   the dCDN, there are cases where there is no privacy concern in making
   detailed CDNI logging information known to the uCDN; this may be the
   case, for example, where (1) it is considered that because the uCDN
   has the authority (with respect to the CSP) and control on how the
   requests are delivered (including whether it is served by the uCDN
   itself or by a dCDN), the uCDN is entitled to access all detailed
   information related to the corresponding deliveries, and (2) there is
   no legal reason to restrict access by the uCDN to all this detailed
   information.  Conversely still, when DNS redirection is used between
   the uCDN and the dCDN, there are cases where there may be some
   privacy concern in making detailed CDNI Logging information known to
   the uCDN; this may be the case, for example, because the uCDN is in a
   different jurisdiction to the dCDN, resulting is some legal reasons
   to restrict access by the uCDN to all the detailed information
   related to the deliveries.  In this latter case, the privacy concerns
   can be taken into account when the uCDN and dCDN agree about which
   fields are to be conveyed inside the CDNI Logging Files and which
   privacy protection mechanism is to be used as discussed in the
   definition of the c-groupid field specified in Section 3.4.1.

   Another privacy concern arises from the fact that large volumes of
   detailed information about content delivery to users, potentially
   traceable back to individual users, may be collected in CDNI Logging
   Files.  These CDNI Logging Files represent high-value targets, likely
   concentrated in a fairly centralized system (although the CDNI



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   Logging architecture does not mandate a particular level of
   centralization/distribution) and at risk of potential data
   exfiltration.  Note that the means of such data exfiltration are
   beyond the scope of the CDNI Logging interface itself (e.g.,
   corrupted employee, corrupted logging storage system, etc.).  This
   privacy concern calls for some protection.

   The collection of large volumes of such information into CDNI Logging
   Files introduces potential end-users' privacy protection concerns.
   Mechanisms to address these concerns are discussed in the definition
   of the c-groupid field specified in Section 3.4.1.

   The use of mutually authenticated TLS to establish a secure session
   for the transport of the CDNI Logging feed and CDNI Logging pull as
   discussed in Section 7.1 provides confidentiality while the Logging
   information is in transit and prevents any party other than the
   authorized uCDN to gain access to the logging information.

   We also note that the query string portion of the URL that may be
   conveyed inside the cs-uri and u-uri fields of CDNI Logging Files, or
   the HTTP cookies( [RFC6265]) that may be conveyed as part of the
   cs(<HTTP-header-name>) field of CDNI Logging Files, may contain
   personal information or information that can be exploited to derive
   personal information.  Where this is a concern, the CDNI Logging
   interface specification allows the dCDN to not include the cs-uri and
   to include a u-uri that removes (or hides) the sensitive part of the
   query string and allows the dCDN to not include the cs(<HTTP-header-
   name>) fields corresponding to HTTP headers associated with cookies.

8.  References

8.1.  Normative References

   [AES]      NIST, "Advanced Encryption Standard (AES)", National
              Institute of Standards and Technology FIPS 197, November
              2001, <http://csrc.nist.gov/publications/fips/fips197/
              fips-197.pdf>.

   [GCM]      NIST, "Recommendation for Block Cipher Modes of Operation:
              Galois/Counter Mode (GCM) and GMAC", National Institute of
              Standards and Technology SP 800-38D,
              DOI 10.6028/NIST.SP.800-38D, November 2007,
              <http://csrc.nist.gov/publications/nistpubs/800-38D/
              SP-800-38D.pdf>.







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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <http://www.rfc-editor.org/info/rfc3339>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <http://www.rfc-editor.org/info/rfc3986>.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              DOI 10.17487/RFC4122, July 2005,
              <http://www.rfc-editor.org/info/rfc4122>.

   [RFC4287]  Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
              Syndication Format", RFC 4287, DOI 10.17487/RFC4287,
              December 2005, <http://www.rfc-editor.org/info/rfc4287>.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <http://www.rfc-editor.org/info/rfc4648>.

   [RFC5005]  Nottingham, M., "Feed Paging and Archiving", RFC 5005,
              DOI 10.17487/RFC5005, September 2007,
              <http://www.rfc-editor.org/info/rfc5005>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <http://www.rfc-editor.org/info/rfc5234>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,
              <http://www.rfc-editor.org/info/rfc7230>.






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   [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
              DOI 10.17487/RFC7231, June 2014,
              <http://www.rfc-editor.org/info/rfc7231>.

   [RFC7232]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
              DOI 10.17487/RFC7232, June 2014,
              <http://www.rfc-editor.org/info/rfc7232>.

   [RFC7233]  Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed.,
              "Hypertext Transfer Protocol (HTTP/1.1): Range Requests",
              RFC 7233, DOI 10.17487/RFC7233, June 2014,
              <http://www.rfc-editor.org/info/rfc7233>.

   [RFC7234]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
              RFC 7234, DOI 10.17487/RFC7234, June 2014,
              <http://www.rfc-editor.org/info/rfc7234>.

   [RFC7235]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Authentication", RFC 7235,
              DOI 10.17487/RFC7235, June 2014,
              <http://www.rfc-editor.org/info/rfc7235>.

   [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
              2015, <http://www.rfc-editor.org/info/rfc7525>.

   [RFC7540]  Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
              Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
              DOI 10.17487/RFC7540, May 2015,
              <http://www.rfc-editor.org/info/rfc7540>.

   [SHA-3]    NIST, "SHA-3 Standard: Permutation-Based Hash and
              Extendable-Output Functions", National Institute of
              Standards and Technology FIPS 202,
              DOI 10.6028/NIST.FIPS.202, August 2015,
              <http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf>.










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8.2.  Informative References

   [ATOMPUB]  Snell, J., "Atom Link Extensions", Work in Progress,
              draft-snell-atompub-link-extensions-09, June 2012.

   [CDNI-META]
              Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,
              "CDN Interconnection Metadata", Work in Progress,
              draft-ietf-cdni-metadata-20, August 2016.

   [CHAR_SET] IANA, "Character Sets",
              <http://www.iana.org/assignments/character-sets>.

   [ELF]      Phillip M. Hallam-Baker, and Brian Behlendorf, "Extended
              Log File Format", W3C Working Draft, WD-logfile-960323,
              <http://www.w3.org/TR/WD-logfile.html>.

   [RFC1945]  Berners-Lee, T., Fielding, R., and H. Frystyk, "Hypertext
              Transfer Protocol -- HTTP/1.0", RFC 1945,
              DOI 10.17487/RFC1945, May 1996,
              <http://www.rfc-editor.org/info/rfc1945>.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
              DOI 10.17487/RFC2818, May 2000,
              <http://www.rfc-editor.org/info/rfc2818>.

   [RFC5869]  Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
              Key Derivation Function (HKDF)", RFC 5869,
              DOI 10.17487/RFC5869, May 2010,
              <http://www.rfc-editor.org/info/rfc5869>.

   [RFC6234]  Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
              (SHA and SHA-based HMAC and HKDF)", RFC 6234,
              DOI 10.17487/RFC6234, May 2011,
              <http://www.rfc-editor.org/info/rfc6234>.

   [RFC6265]  Barth, A., "HTTP State Management Mechanism", RFC 6265,
              DOI 10.17487/RFC6265, April 2011,
              <http://www.rfc-editor.org/info/rfc6265>.

   [RFC6707]  Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
              Distribution Network Interconnection (CDNI) Problem
              Statement", RFC 6707, DOI 10.17487/RFC6707, September
              2012, <http://www.rfc-editor.org/info/rfc6707>.







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   [RFC6770]  Bertrand, G., Ed., Stephan, E., Burbridge, T., Eardley,
              P., Ma, K., and G. Watson, "Use Cases for Content Delivery
              Network Interconnection", RFC 6770, DOI 10.17487/RFC6770,
              November 2012, <http://www.rfc-editor.org/info/rfc6770>.

   [RFC6983]  van Brandenburg, R., van Deventer, O., Le Faucheur, F.,
              and K. Leung, "Models for HTTP-Adaptive-Streaming-Aware
              Content Distribution Network Interconnection (CDNI)",
              RFC 6983, DOI 10.17487/RFC6983, July 2013,
              <http://www.rfc-editor.org/info/rfc6983>.

   [RFC7336]  Peterson, L., Davie, B., and R. van Brandenburg, Ed.,
              "Framework for Content Distribution Network
              Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336,
              August 2014, <http://www.rfc-editor.org/info/rfc7336>.

   [RFC7337]  Leung, K., Ed. and Y. Lee, Ed., "Content Distribution
              Network Interconnection (CDNI) Requirements", RFC 7337,
              DOI 10.17487/RFC7337, August 2014,
              <http://www.rfc-editor.org/info/rfc7337>.

   [RFC7736]  Ma, K., "Content Delivery Network Interconnection (CDNI)
              Media Type Registration", RFC 7736, DOI 10.17487/RFC7736,
              December 2015, <http://www.rfc-editor.org/info/rfc7736>.

   [TLS-1.3]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", Work in Progress, draft-ietf-tls-tls13-15,
              August 2016.























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Acknowledgments

   This document borrows from the W3C Extended Log Format [ELF].

   Rob Murray significantly contributed into the text of Section 4.1.
   The authors thank Ben Niven-Jenkins, Kevin Ma, David Mandelberg, and
   Ray van Brandenburg for their ongoing input.

   Brian Trammel and Rich Salz made significant contributions into
   making this interface privacy-friendly.

   Finally, we also thank Sebastien Cubaud, Pawel Grochocki, Christian
   Jacquenet, Yannick Le Louedec, Anne Marrec, Emile Stephan, Fabio
   Costa, Sara Oueslati, Yvan Massot, Renaud Edel, Joel Favier, and the
   contributors of the EU FP7 OCEAN project for their input in the early
   draft versions of this document.

Authors' Addresses

   Francois Le Faucheur (editor)
   France

   Phone: +33 6 19 98 50 90
   Email: flefauch@gmail.com


   Gilles Bertrand (editor)

   Phone: +41 76 675 91 44
   Email: gilbertrand@gmail.com


   Iuniana Oprescu (editor)
   France

   Email: iuniana.oprescu@gmail.com


   Roy Peterkofsky
   Google Inc.
   345 Spear St, 4th Floor
   San Francisco  CA 94105
   United States of America

   Email: peterkofsky@google.com






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