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rfc:rfc7937

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.

Le Faucheur, et al. Standards Track [Page 1] RFC 7937 CDNI Logging August 2016

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

Le Faucheur, et al. Standards Track [Page 2] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 3] RFC 7937 CDNI Logging August 2016

 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

Le Faucheur, et al. Standards Track [Page 4] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 5] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 6] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 7] RFC 7937 CDNI Logging August 2016

                 +-----+
                 | 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.

Le Faucheur, et al. Standards Track [Page 8] RFC 7937 CDNI Logging August 2016

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.

Le Faucheur, et al. Standards Track [Page 9] RFC 7937 CDNI Logging August 2016

           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.

Le Faucheur, et al. Standards Track [Page 10] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 11] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 12] RFC 7937 CDNI Logging August 2016

 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

Le Faucheur, et al. Standards Track [Page 13] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 14] RFC 7937 CDNI Logging August 2016

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)

Le Faucheur, et al. Standards Track [Page 15] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 16] RFC 7937 CDNI Logging August 2016

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].

Le Faucheur, et al. Standards Track [Page 17] RFC 7937 CDNI Logging August 2016

    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.

Le Faucheur, et al. Standards Track [Page 18] RFC 7937 CDNI Logging August 2016

 +----------------------------------------------------------+
 |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

Le Faucheur, et al. Standards Track [Page 19] RFC 7937 CDNI Logging August 2016

 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."

Le Faucheur, et al. Standards Track [Page 20] RFC 7937 CDNI Logging August 2016

    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

Le Faucheur, et al. Standards Track [Page 21] RFC 7937 CDNI Logging August 2016

 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).

Le Faucheur, et al. Standards Track [Page 22] RFC 7937 CDNI Logging August 2016

  • 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".

Le Faucheur, et al. Standards Track [Page 23] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 24] RFC 7937 CDNI Logging August 2016

  • 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-

Le Faucheur, et al. Standards Track [Page 25] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 26] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 27] RFC 7937 CDNI Logging August 2016

 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

Le Faucheur, et al. Standards Track [Page 28] RFC 7937 CDNI Logging August 2016

          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:
  1. 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).
  1. It is RECOMMENDED that the mapping varies at least once

every 24 hours.

  1. 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.
  1. 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.
  1. 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

Le Faucheur, et al. Standards Track [Page 29] RFC 7937 CDNI Logging August 2016

                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.

Le Faucheur, et al. Standards Track [Page 30] RFC 7937 CDNI Logging August 2016

  • 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.

Le Faucheur, et al. Standards Track [Page 31] RFC 7937 CDNI Logging August 2016

  • 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.

Le Faucheur, et al. Standards Track [Page 32] RFC 7937 CDNI Logging August 2016

  • 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

Le Faucheur, et al. Standards Track [Page 33] RFC 7937 CDNI Logging August 2016

       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.

Le Faucheur, et al. Standards Track [Page 34] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 35] RFC 7937 CDNI Logging August 2016

 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

Le Faucheur, et al. Standards Track [Page 36] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 37] RFC 7937 CDNI Logging August 2016

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.

Le Faucheur, et al. Standards Track [Page 38] RFC 7937 CDNI Logging August 2016

 #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>

Le Faucheur, et al. Standards Track [Page 39] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 40] RFC 7937 CDNI Logging August 2016

 #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

Le Faucheur, et al. Standards Track [Page 41] RFC 7937 CDNI Logging August 2016

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,

Le Faucheur, et al. Standards Track [Page 42] RFC 7937 CDNI Logging August 2016

 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)

Le Faucheur, et al. Standards Track [Page 43] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 44] RFC 7937 CDNI Logging August 2016

 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]).

Le Faucheur, et al. Standards Track [Page 45] RFC 7937 CDNI Logging August 2016

 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).

Le Faucheur, et al. Standards Track [Page 46] RFC 7937 CDNI Logging August 2016

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.

Le Faucheur, et al. Standards Track [Page 47] RFC 7937 CDNI Logging August 2016

 <?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

Le Faucheur, et al. Standards Track [Page 48] RFC 7937 CDNI Logging August 2016

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.

Le Faucheur, et al. Standards Track [Page 49] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 50] RFC 7937 CDNI Logging August 2016

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.

Le Faucheur, et al. Standards Track [Page 51] RFC 7937 CDNI Logging August 2016

 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]).

Le Faucheur, et al. Standards Track [Page 52] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 53] RFC 7937 CDNI Logging August 2016

 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]).

Le Faucheur, et al. Standards Track [Page 54] RFC 7937 CDNI Logging August 2016

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.

Le Faucheur, et al. Standards Track [Page 55] RFC 7937 CDNI Logging August 2016

 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.

Le Faucheur, et al. Standards Track [Page 56] RFC 7937 CDNI Logging August 2016

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

Le Faucheur, et al. Standards Track [Page 57] RFC 7937 CDNI Logging August 2016

 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>.

Le Faucheur, et al. Standards Track [Page 58] RFC 7937 CDNI Logging August 2016

 [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>.

Le Faucheur, et al. Standards Track [Page 59] RFC 7937 CDNI Logging August 2016

 [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>.

Le Faucheur, et al. Standards Track [Page 60] RFC 7937 CDNI Logging August 2016

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>.

Le Faucheur, et al. Standards Track [Page 61] RFC 7937 CDNI Logging August 2016

 [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.

Le Faucheur, et al. Standards Track [Page 62] RFC 7937 CDNI Logging August 2016

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

Le Faucheur, et al. Standards Track [Page 63]

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