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Versions: (draft-bertrand-cdni-logging) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 RFC 7937

Internet Engineering Task Force                         G. Bertrand, Ed.
Internet-Draft                                           I. Oprescu, Ed.
Intended status: Informational                   France Telecom - Orange
Expires: November 28, 2013                           F. Le Faucheur, Ed.
                                                           Cisco Systems
                                                          R. Peterkofsky
                                                           Skytide, Inc.
                                                            May 27, 2013


                         CDNI Logging Interface
                       draft-ietf-cdni-logging-02

Abstract

   This memo specifies the Logging interface between a downstream CDN
   (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 Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on November 28, 2013.

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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  CDNI Logging Reference Model  . . . . . . . . . . . . . . . .   5
     2.1.  CDNI Logging interactions . . . . . . . . . . . . . . . .   5
     2.2.  Overall Logging Chain . . . . . . . . . . . . . . . . . .   8
       2.2.1.  Logging Generation and During-Generation Aggregation    9
       2.2.2.  Logging Collection  . . . . . . . . . . . . . . . . .  10
       2.2.3.  Logging Filtering . . . . . . . . . . . . . . . . . .  10
       2.2.4.  Logging Rectification and Post-Generation Aggregation  11
       2.2.5.  Log-Consuming Applications  . . . . . . . . . . . . .  12
         2.2.5.1.  Maintenance/Debugging . . . . . . . . . . . . . .  12
         2.2.5.2.  Accounting  . . . . . . . . . . . . . . . . . . .  12
         2.2.5.3.  Analytics and Reporting . . . . . . . . . . . . .  13
         2.2.5.4.  Security  . . . . . . . . . . . . . . . . . . . .  13
         2.2.5.5.  Legal Logging Duties  . . . . . . . . . . . . . .  13
         2.2.5.6.  Notions common to multiple Log Consuming
                   Applications  . . . . . . . . . . . . . . . . . .  13
   3.  CDNI Logging File Format  . . . . . . . . . . . . . . . . . .  15
     3.1.  CDNI Logging File Directives  . . . . . . . . . . . . . .  16
     3.2.  Logging Records . . . . . . . . . . . . . . . . . . . . .  19
       3.2.1.  HTTP Request Logging Record . . . . . . . . . . . . .  20
       3.2.2.  CDNI Logging File Example . . . . . . . . . . . . . .  26
     3.3.  Fields and Directives Formats . . . . . . . . . . . . . .  27
   4.  CDNI Logging File Exchange Protocol . . . . . . . . . . . . .  27
     4.1.  CDNI Logging Feed . . . . . . . . . . . . . . . . . . . .  28
     4.2.  CDNI Logging File Pull  . . . . . . . . . . . . . . . . .  28
   5.  Open Issues . . . . . . . . . . . . . . . . . . . . . . . . .  29
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  31



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   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  31
     7.1.  Authentication, Confidentiality, Integrity Protection . .  31
     7.2.  Non Repudiation . . . . . . . . . . . . . . . . . . . . .  32
     7.3.  Privacy . . . . . . . . . . . . . . . . . . . . . . . . .  32
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  32
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  33
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  33
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  33
   Appendix A.  Requirements . . . . . . . . . . . . . . . . . . . .  34
     A.1.  Compliance with cdni-requirements . . . . . . . . . . . .  34
     A.2.  Additional Requirements . . . . . . . . . . . . . . . . .  34
       A.2.1.  Timeliness  . . . . . . . . . . . . . . . . . . . . .  34
       A.2.2.  Reliability . . . . . . . . . . . . . . . . . . . . .  35
       A.2.3.  Security  . . . . . . . . . . . . . . . . . . . . . .  35
       A.2.4.  Scalability . . . . . . . . . . . . . . . . . . . . .  35
       A.2.5.  Consistency between CDNI Logging and CDN Logging  . .  35
       A.2.6.  Dispatching/Filtering . . . . . . . . . . . . . . . .  35
   Appendix B.  Analysis of candidate protocols for Logging
                Transport  . . . . . . . . . . . . . . . . . . . . .  36
     B.1.  Syslog  . . . . . . . . . . . . . . . . . . . . . . . . .  36
     B.2.  XMPP  . . . . . . . . . . . . . . . . . . . . . . . . . .  36
     B.3.  SNMP  . . . . . . . . . . . . . . . . . . . . . . . . . .  36
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  36

1.  Introduction

   This memo specifies the 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
      [I-D.ietf-cdni-framework] identify a Logging interface,

   o  Section 8 of [I-D.ietf-cdni-requirements] 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.

   As stated in [RFC6707], "the CDNI Logging interface enables details
   of logs or events to be exchanged between interconnected CDNs".

   The present document describes:




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   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
   [I-D.ietf-cdni-framework], and extend it with the additional terms
   defined below.

   For clarity, we use the word "Log" only for referring to internal CDN
   logs and we use the word "Logging" for any inter-CDN information
   exchange and processing operations related to CDNI Logging interface.
   Log and Logging formats may be different.

   CDN Logging information: logging information generated and collected
   within a CDN

   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
   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 CSP in deferred time.  Such information typically includes
   aggregated data that can cover a large 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).



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   CDN Monitoring: the process of providing content delivery information
   in real-time.  Monitoring typically includes data in real time to
   provide 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.

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 logging
      fields are to be communicated to the uCDN for a given task
      performed by the dCDN, 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
      customisation by the uCDN of CDNI Logging information is outside
      the scope of this document and left for further study.  We note
      that the CDNI Control interface or the CDNI Metadata interface
      appear as candidate interfaces on which to potentially build such
      a customisation mechanism in the future.  Before such a mechanism
      is available, the uCDN and dCDN are expected to agree off-line on
      what CDNI logging information is to be provide by dCDN to UCDN and
      rely on management plane actions to configure the CDNI Logging
      functions to generate (respectively, expect) in dCDN
      (respectively, in uCDN).

   o  generation and collection by the dCDN of 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



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      the CDNI Logging interface and 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 trouble-shooting.

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

   o  generation and collection by the uCDN of 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 form this information for security
      auditing or content acquisition troubleshooting.  This is outside
      the scope of this document and left for further study.

   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 4 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, dCDN2 has a CDNI interconnection with
   dCDN3.  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, uCDN uses the Logging data:

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

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

   For instance, uCDN merges Logging data, 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 his behalf.  uCDN
   may also provide Logging data as raw log files to the CSP, so that
   the CSP can use its own logging analysis tools.




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

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


          Figure 1: Interactions in CDNI Logging Reference Model

   A dCDN (e.g., dCDN-2) integrates the relevant logging information
   obtained from its dCDNs (e.g., 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.

   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 data 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 format that are suitable for use inside CDNs
   and also are close to the CDN Log formats commonly used in CDNs
   today.





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2.2.  Overall Logging Chain

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






































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             Log Consuming    Log Consuming
                 App              App
                 /\              /\
                 |               |
           Rectification--------
           /\
           |
           Filtering
            /\
            |
        Collection                        uCDN
        /\       /\
        |        |
        |     Generation
        |
   CDNI Logging ---------------------------------------------
   exchange
        /\         Log Consuming    Log Consuming
        |                 App              App
        |                  /\              /\
        |                  |               |
   Rectification     Rectification---------
           /\       /\
           |        |
           Filtering
            /\
            |
         Collection                         dCDN
         /\       /\
         |        |
   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.  Logs are typically generated by
   many devices in the CDN including the surrogates, the request routing
   system, and the control system.

   The amount of Logging information generated can be huge.  Therefore,
   during contract negotiations, interconnected CDNs often agree on a



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   Logging retention duration, and optionally, on a maximum size of the
   Logging data that the dCDN must keep.  If this size is exceeded, the
   dCDN must alert the uCDN but may not keep more Logs for the
   considered time period.  In addition, CDNs may aggregate logs and
   transmit only summaries for some categories of operations instead of
   the full Logging data.  Note that such aggregation leads to an
   information loss, which may be problematic for some usages of Logging
   (e.g., debugging).

   [I-D.brandenburg-cdni-has] 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 [I-D.brandenburg-cdni-has], the logging
   information for per-chunck 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 this may be revisited in future versions
   of this document.

   Note that in the case of non real-time logging, the trigger of the
   transmission or generation of the logging file appears to be a
   synchronous process from a protocol standpoint.  The implementation
   algorithm can choose to enforce a maximum size for the logging file
   beyond which the transmission is automatically triggered (and thus
   allow for an asynchronous transmission process).

2.2.2.  Logging Collection

   This is the process that continuously collects logs 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 through CDNI Logging
   exchange with the dCDN through the CDNI Logging interface.

2.2.3.  Logging Filtering




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   A CDN may require to only present different subset of the whole
   logging information collected to various log-consuming applications.
   This is achieved by the Filtering process.

   In particular, the Filtering process can also filter the right subset
   of 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 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 set of log records that
   relate 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 every Surrogate may be
   confidential.  Therefore, the Logging information must be protected
   so that data such as Surrogates' hostnames is 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 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 of this period will be available only after the end
   of the session, which delays the Logging generation.

   A Logging rectification/update mechanism could be useful to reach a
   good trade-off between the Logging generation delay and the Logging
   accuracy.  Depending on the selected Logging protocol(s), such
   mechanism may be invaluable for real time Logging, which must be
   provided rapidly and cannot wait for the end of operations in
   progress.




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   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.
   In the case where the log-generating entities have generated during-
   generation aggregate logs, 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
   [I-D.brandenburg-cdni-has], this document does not define exchange of
   such aggregate logs on the CDNI Logging interface.  We note that this
   may be revisited in future versions of this document.

2.2.5.  Log-Consuming Applications

2.2.5.1.  Maintenance/Debugging

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

   To detect faults, Logging must enable the reporting of any CDN
   operation success and failure, such as request redirection, content
   acquisition, etc.  The uCDN can summarize such information into KPIs.
   For instance, Logging format should allow the computation of the
   number of times during a given epoch that content delivery related to
   a specific service succeeds/fails.

   Logging enables the CDN providers to identify and troubleshoot
   performance degradations.  In particular, Logging enables the
   communication 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.

2.2.5.2.  Accounting

   Logging 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.




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2.2.5.3.  Analytics and Reporting

   The goal of analytics is to gather any relevant information to track
   audience, analyze user behavior, and monitor the performance and
   quality of content delivery.  For instance, Logging 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.  Security

   The goal of security is to prevent and monitor unauthorized access,
   misuse, modification, and denial of access of a service.  A set of
   information is logged 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.

2.2.5.5.  Legal Logging Duties

   Depending on the country considered, the CDNs may have to retain
   specific Logging information during a legal retention period, to
   comply with judicial requisitions.

2.2.5.6.  Notions common to multiple Log Consuming Applications

2.2.5.6.1.  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 an 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.





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2.2.5.6.2.  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 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)

   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)






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   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 of the most popularly requested content (during a given day
      /week/month),

   o  Terminal type (mobile, PC, STB, if this information can be
      acquired from the browser type header, for example).

   Additional KPIs can be computed from other sources of information
   than the Logging, 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 memo.

   The KPIs used depend strongly on the considered log-consuming
   application -- the CDN operator may be interested in different
   metrics than the CSP is.  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 real-time.  By contrast, some
   other KPIs, such as the one averaged on a long period of time, can be
   provided in non-real time.

3.  CDNI Logging File Format

   As defined in Section 1.1 a CDNI logging field is as an atomic
   logging information element and a CDNI Logging Record is a collection
   of CDNI Logging Fields containing all logging information
   corresponding to a single logging event.  This document defines a
   third level of structure, the CDNI Logging File, that is a collection
   of CDNI Logging Records.  This structure is illustrated in Figure 3.
   The CDNI Logging File structure and encoding is specified in the
   present section.

   +------------------------------------------------------+
   |CDNI Logging File                                     |
   |                                                      |
   | +--------------------------------------------------+ |
   | |CDNI Logging Record                               | |
   | |  +-------------+ +-------------+ +-------------+ | |
   | |  |CDNI Logging | |CDNI Logging | |CDNI Logging | | |
   | |  |   Field     | |   Field     | |   Field     | | |



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   | |  +-------------+ +-------------+ +-------------+ | |
   | +--------------------------------------------------+ |
   |                                                      |
   | +--------------------------------------------------+ |
   | |CDNI Logging Record                               | |
   | |  +-------------+ +-------------+ +-------------+ | |
   | |  |CDNI Logging | |CDNI Logging | |CDNI Logging | | |
   | |  |   Field     | |   Field     | |   Field     | | |
   | |  +-------------+ +-------------+ +-------------+ | |
   | +--------------------------------------------------+ |
   |                                                      |
   | +--------------------------------------------------+ |
   | |CDNI Logging Record                               | |
   | |  +-------------+ +-------------+ +-------------+ | |
   | |  |CDNI Logging | |CDNI Logging | |CDNI Logging | | |
   | |  |   Field     | |   Field     | |   Field     | | |
   | |  +-------------+ +-------------+ +-------------+ | |
   | +--------------------------------------------------+ |
   +------------------------------------------------------+


                   Figure 3: Structure of Logging Files

   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 CDNI Logging MUST comply with
   the present document.

   A CDNI Logging File MUST contain a sequence of lines containing US-
   ASCII characters [CHAR_SET] terminated by either the sequence LF or
   CRLF.  A CDNI Logging implementation consuming CDNI Logging Files
   MUST accept lines terminated by either LF or 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 3.1.

   Logging Records provide actual details of the logged event.  Logging
   Records are specified in Section 3.2.

3.1.  CDNI Logging File Directives






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   An implementation of the CDNI Logging interface MUST support the
   following directives (formats specified in the form <...> are
   specified in Section 3.3):

   o  Version:

      *  format: <digit>.<digit>

      *  semantic: indicates the version of the CDNI Logging File
         format.  The value MUST be "1.0" for the version specified in
         the present document.

      *  occurrence: there MUST be one and only one instance of this
         directive.  It MUST be the first line of the CDNI Logging file.

   o  UUID:

      *  format: <string>

      *  semantic: this is Universally Unique IDentifier for the CDNI
         Logging File as specified in [RFC4122].

      *  occurrence: there MUST be one and only one instance of this
         directive.

   o  Origin:

      *  format: <host>

      *  semantic: this identifies 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 one instance of this
         directive.  This directive MAY be included by the
         implementation transmitting the CDNI Logging file.  When
         included by the transmitting side, it MUST be validated or
         over-written by the receiving side.  When, it is not included
         by the transmitting side, it MAY be added locally by the
         receiving side.  [Editor's Note if we include a non-repudiation
         mechanism: discuss the fact that this will provide incentive to
         dCDN to not cheat , as it can be detected]

   o  Record-Type:

      *  format: <string>




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      *  semantic: indicates the type of the CDNI Logging Records that
         follow this directive, until another Record-Type directive (or
         the end of the CDNI Logging File).  "cdni_http_request_v1" MUST
         be indicated in the Record-Type directive for CDNI Logging
         records corresponding to HTTP request (e.g.  a HTTP delivery
         request) as specified in Section 3.2.1.

      *  occurrence: there MUST be at least one instance of this
         directive.  The first instance of this directive MUST precede a
         Fields directive and precede any CDNI Logging Record.

   o  Fields:

      *  format: <field-name>[ <field-name>], where the allowed list of
         <field-name> are specified for each Record-Type in Section 3.2.

      *  semantic: this lists the names of all the fields for which a
         value is to appear in the CDNI Logging Records that are after
         this directive.  The names of the fields, as well as their
         possible occurrences, are specified for each type of CDNI
         Logging Records in Section 3.2.  The field names listed in this
         directive MUST be separated by a whitespace (" ").

      *  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 precede any CDNI
         Logging Record for this Record-Type.

   o  Integrity-Hash:

      *  format: <string>

      *  semantic: This directive permits the detection of a corrupted
         CDNI Logging File.  This can be useful, for instance, if a
         problem occurs on the filesystem of the dCDN Logging system and
         leads to a truncation of a logging file.  The Integrity-Hash
         value is computed, and included in this directive by the entity
         that transmits the CDNI Logging File, by applying the MD5
         ([RFC1321]) cryptographic hash function on the CDNI Logging
         File, including all the directives and logging records, up to
         the Intergrity-Hash directive itself, excluding the Integrity-
         Hash directive itself and, when present, also excluding the
         Non-Repudiation-Hash directive.  The Integrity-Hash value is
         represented as a US-ASCII encoded hexadecimal number, 32 digits
         long (representing a 128 bit hash value).  The entity receiving
         the CDNI Logging File also computes in a similar way the MD5
         hash on the received CDNI Logging File and compares this hash
         to the value of the Integrity-Hash directive.  If the two



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         values are equal, then the received CDNI Logging File MUST be
         considered non-corrupted.  If the two values are different, the
         received CDNI Logging File MUST 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 again the same CDNI Logging file
         from the transmitting entity.

      *  occurrence: there MUST be one and only one instance of this
         directive.  This field MUST be the last line of the CDNI
         Logging File when the Non-Repudiation-Hash is absent, and MUST
         be the one before last line of the CDNI Logging File when the
         Non-Repudiation-Hash is present.

   o  Non-Repudiation-Hash:

      *  format: <string>

      *  semantic: This hash field permits the non-repudiation of the
         CDNI Logging File by the entity that transmitted the CDNI
         Logging File.  [Editor's Note: I need help for specifying the
         appropriate hash - ie hash must be signed with private-key of
         entity transmitting the CDNI Logging File]

      *  occurrence: there MAY be one and only one instance of this
         directive.  When present, this directive MUST be the last line
         of the CDNI Logging File.

3.2.  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
   (TAB)" character.

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

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

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

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



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

   [Editor's Note: see discussion with Rob about adding definition for
   "r"]

   An implementation of the CDNI Logging interface as per the present
   specification MUST support the CDNI HTTP Delivery Records as
   specified in Section 3.2.1.  [Editor's Note": other types of delivery
   records will be listed here if we specify other types for this
   version eg Request Routing].

   The formats listed in this section in the form <...> are specified in
   Section 3.3).

3.2.1.  HTTP Request Logging Record

   The HTTP Request Logging Record contains the following CDNI Logging
   Fields, listed by their field name:

   o  date:

      *  format: <date>

      *  semantic: the date at which the processing of request started
         on the Surrogate.

      *  occurrence: there MUST be one and only one instance of this
         field.

   o  time:

      *  format: <time>

      *  semantic: the time at which the processing of request started
         on the Surrogate.

      *  occurrence: there MUST be one and only one instance of this
         field.

   o  time-taken:

      *  format: <fixed>

      *  semantic: duration, in seconds, between the start of the
         processing of the request and the completion of the delivery by
         the Surrogate.




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      *  occurrence: there MUST be one and only one instance of this
         field.

   o  c-ip:

      *  format: <address>

      *  semantic: the source IPv4 or IPv6 address (i.e.  the "client"
         address) in the request received by the Surrogate.

      *  occurrence: there MUST be one and only one instance of this
         field.

   o  c-port:

      *  format: <integer>

      *  semantic: the source TCP port (i.e.  the "client" port) in the
         request received by the Surrogate.

      *  occurrence: there MUST be zero or exactly one instance of this
         field.

   o  s-ip:

      *  format: <address>

      *  semantic: 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>

      *  semantic: 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: <integer>





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      *  semantic: the destination TCP port (i.e.  the "server" port) in
         the request received by the Surrogate.

      *  occurrence: there MUST be zero or exactly one instance of this
         field.

   o  cs-method:

      *  format: <string>

      *  semantic: this is the HTTP method of the HTTP request received
         by the Surrogate.

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

   o  cs-uri: [Editor's note: rename "sr-uri" ?]

      *  format: <uri>

      *  semantic: this is the absolute-URI of the request received by
         the Surrogate.  [Editor's Note: do we agree this should be an
         absolute-URI even if teh request uses a relative-URI?]

      *  occurrence: there MUST be zero or exactly one instance of this
         field.

   o  ucdn-centric-uri:

      *  format: <uri>

      *  semantic: this is an absolute URI derived from the absolute-URI
         of the request received by the Surrogate but modified 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.  For example, the two ends of the CDNI
         Logging interface could agree that the ucdn-centric-uri strips
         the part of the delivery-uri that exposes which individual
         Surrogate actually performed the delivery.  The details of
         modification performed to generate the ucdn-centric-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.  [Editor's Note: do we agree
         this should be an absolute-URI even if the request uses a
         relative-URI?]

      *  occurrence: there MUST be one and only one instance of this
         field.



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   o  protocol:

      *  format: <string>

      *  semantic: this is value of the HTTP-Version field as specified
         in [RFC2616] 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: <digit><digit><digit>

      *  semantic: this is the HTTP Status-Code in the HTTP response
         from the Surrogate.

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

   o  sc-total-bytes:

      *  format: <integer>

      *  semantic: this is the total number of bytes of the HTTP
         response sent by the Surrogate in response to the request.
         This includes the bytes of the Status-Line (including HTTP
         headers) and of the message-body.

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

   o  sc-entity-bytes:

      *  format: <integer>

      *  semantic: 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
         (and therefore does not include the bytes of the HTTP headers).

      *  occurrence: there MUST be zero or exactly one instance of this
         field.

   o  cs(<HTTP-header>):

      *  format: <string>



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      *  semantic: the value of the HTTP header identified in the field
         name as it appears in the request processed by the Surrogate.

      *  occurrence: there MUST be zero, one or any number of instance
         of this field.

   o  sc(<HTTP-header>):

      *  format: <string>

      *  semantic: the value of the HTTP header identified in the field
         name as it appears in the response issued by the Surrogate to
         serve the request.

      *  occurrence: there MUST be zero, one or any number of instance
         of this field.

   o  s-ccid:

      *  format: [Editor's Note: to be based on cdni-metadata or
         relevant companion I-D]

      *  semantic: this contains the value of the Content Collection
         IDentifier specified in [I-D.ietf-cdni-metadata] and associated
         to the content served by the Surrogate through the CDNI
         Metadata interface.

      *  occurrence: there MUST be zero or exactly one instance of this
         field.

   o  s-sid:

      *  format: [Editor's Note: add reference to the I-D defining the
         format of Session ID>?]

      *  semantic: this contains the value of the Session IDentifier
         specified in ??? and associated to the served request by the
         Surrogate.

      *  occurrence: there MUST be zero or exactly one instance of this
         field.

   o  s-cached: [Editor's Note: W3C uses "cached" . is "s-cached"
      better?]

      *  format: <string>





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      *  semantic: this characterises whether the Surrogate could serve
         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 could serve the request using
         exclusively 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 the content was already stored, or not, in another
         device of the dCDN i.e.  whether this was a "dCDN hit" or "dCDN
         miss".

      *  occurrence: there MUST be zero or exactly one instance of this
         field.

   o  s-uri-signing:

      *  format: <string>

      *  semantic: this characterises the uri signing validation
         performed by the Surrogate on the request.  The allowed values
         are:

      *

         +  "0" : no uri signature validation performed

         +  "1" : uri signature validation performed and validated

         +  "2" : uri signature validation performed and rejected

      *  occurrence: there MUST be zero or exactly one instance of this
         field.

   The "Fields" directive corresponding to a HTTP Request Logging Record
   MUST list all the fields whose occurrence is specified above as
   "There MUST be one and only one instance of this field".  These
   fields MUST be present in every HTTP Request Logging Record.

   The "Fields" directive corresponding to a HTTP Request Logging Record
   MAY list all the fields whose occurrence is specified above as "there
   MUST be zero or exactly one instance of this field" or "there MUST be
   zero, one or any number of instance of this field".  The set of such
   fields actually listed in the "Fields" directive is selected by the
   implementation generating the CDNI Logging File based on agreements
   between the interconnected CDNs established through mechanisms
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   agreements) . When such a field is not listed in the "Fields"
   directive, it MUST NOT be included in the Logging Record.  When such
   a field is listed in the "Fields" directive, it MUST be included in
   the Logging Record; in that case, if the value for the field is not
   available, this MUST be conveyed via a dash character ("-").

   The fields listed in the "Fields" directive can be listed in the
   order in which they are listed in Section 3.2.1 or in any other
   order.

   [Editor's Note: discuss private fields ]

3.2.2.  CDNI Logging File Example

   #Version: 1.0

   #UUID: urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6???

   #Origin: cdni-logging-entity.dcdn.example.com

   #Record-Type: cdni_http_request_v1

   #Fields: date time time-taken c-ip cs-method ucdn-centric-uri
   protocol sc-status sc-total-bytes cs(User-Agent) cs(Referer) s-cached

   2013-05-17 00:38:06.825 88.958 10.5.7.1 GET http://cdni-
   ucdn.dcdn.example.com/video/movie100.mp4 HTTP/1.1 200 672989 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 host1.example.com 1

   2013-05-17 00:39:09.145 169.790 10.5.10.5 GET http://cdni-
   ucdn.dcdn.example.com/video/movie118.mp4 HTTP/1.1200 1579920 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 host1.example.com 1

   2013-05-17 00:42:53.437 2.879 10.5.10.5 GET http://cdni-
   ucdn.dcdn.example.com/video/picture11.mp4 HTTP/1.0 200 17724 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 host5.example.com 0

   #Integrity-Hash: 9e107d9d372bb6826bd81d3542a419d6 [Editor's Note:
   include the correct MD5-hash value for the actual example]









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3.3.  Fields and Directives Formats

   [Editor's Note: still needs work to minimise the number of types
   defined across this section and specific types defined inside the
   field definitions themselves]

   o  <digit> = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" |
      "9"

   o  <integer> = 1*<digit>

   o  <address> = <integer> [ "."  *<integer> ] [ ":" <integer> ]

   o  <host> = as specified in [RFC3986].

   o  <date> = 4<digit> "-" 2<digit> "-" 2<digit>

      *  Dates are recorded in the format YYYY-MM-DD where YYYY, MM and
         DD stand for the numeric year, month and day respectively.  All
         dates are specified in Universal Time Coordinated (UTC).

   o  <time> = 2<digit> ":" 2<digit> ":" 2<digit> ["."  *<digit>]

      *  Times are recorded in the form HH:MM:SS or HH:MM:SS.S where HH
         is the hour in 24 hour format, MM is minutes and SS is seconds.
         All times are specified in Universal Time Coordinated (UTC).

   o  <uri> = <string> containing a URI as specified in [RFC3986].

   o  <fixed> = Fixed Format Float = 1*<digit> [.  *<digit>]

   o  <HTTP-header> = <string> containing a HTTP header field name (e.g.
      "User-Agent", "Referer") as specified in [RFC2616].

4.  CDNI Logging File Exchange Protocol

   This document specifies a protocol for the exchange of CDNI Logging
   Files as specified in Section 3.

   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 File.  The CDNI Logging feed is specified in
      Section 4.1.





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

   An implementation of the CDNI Logging interface as per the present
   document generating CDNI Logging file (i.e.  on the dCDN side) MUST
   support the server side of the CDNI Logging feed and the server side
   of the CDNI Logging pull mechanism.

   An implementation of the CDNI Logging interface as per the present
   document consuming CDNI Logging file (i.e.  on the uCDN side) MUST
   support the client side of the CDNI Logging feed and the client side
   of the CDNI Logging pull mechanism.

   [Editor's note: verify that the client side and server side are well
   defined in the respective sections]

   We note that implementations of the CDNI Logging interface MAY also
   support other mechanisms to exchange CDNI Logging Files, for example
   in view of exchanging logging information with minimum time-lag (e.g.
   sub-minute or sub-second) between when the event occurred in the dCDN
   and when the corresponding Logging Record is made available to the
   uCDN (e.g.  for log-consuming applications requiring extremely fresh
   logging information such as near-real-time content delivery
   monitoring).  Such mechanism might be defined in future version of
   the present document.

4.1.  CDNI Logging Feed

   [Editor's Note: text to be added.  Feed is based on ATOM and contains
   a UUID + URI for each CDNI Logging File in "window" - if appropriate
   the text should refer to the side generating the CDNI Logging Feed
   "as server-side", and the side consuming the Feed as the client-
   side].

4.2.  CDNI Logging File Pull

   A client-side implementation of the CDNI Logging interface MAY pull
   at its convenience any CDNI Logging File that is advertised by the
   server-side in the CDNI Logging Feed.  To do so, the client-side:

   o  MUST use HTTP v1.1

   o  SHOULD use TLS (i.e.  use what is loosely referred to as "HTTPS")

   o  MUST use the URI associated to the CDNI Logging File in the CDNI
      Logging Feed




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   o  SHOULD indicate the compression schemes it supports

   Note that a client-side implementation of the CDNI Logging interface
   MAY pull a CDNI Logging File that it has already pulled, as long as
   the file is still advertised by the server-side in the CDNI Logging
   Feed.

   The server-side implementation MUST respond to any valid pull request
   by a client-side implementation for a CDNI Logging File advertised by
   the server-side in the CDNI Logging Feed.  The server-side
   implementation:

   o  MUST handle the client-side request as per HTTP v1.1

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

   o  MUST support the gzip and deflate compression schemes

   o  MAY support other compression schemes

   o  when the client-side request indicates client-supported
      compression schemes, SHOULD use a compression scheme that it
      supports and is supported by the client-side

   [Editor's Note: discuss Non-Repudiation : it is a nice to have and
   how it could be supported, via a different digest than the one for
   integrity]

5.  Open Issues

   o  The proposed format for Date and Time is based on W3C and is only
      in UTC.  Is this all OK?  RFC 5322 (Section 3.3) format could be
      used or ISO 8601 formatted date and time in UTC (same format as
      proposed in [draft-caulfield-cdni-metadata-core-00]).  Also see
      RFC5424 Section 6.2.3.  We currently use same field names as W3C
      since we have same definition.

   o  (comment from Kevin) how are errors handled ? If the client gets
      handed a bunch of 403s and 404s, but still gets the content
      eventually, without triggering an event, are those still logged?
      For Bytes-Sent, if there were aborted requests, do those get
      counted as well?  Not all client behavior can be correlated with
      the simplified log

   o  Do we need to specify Logs for Request Routing performed by dCDN?
      Observation: Probably can be generalized to the requirement for
      "event" logging (e.g.  dCDN request Router not able to redirect,



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      dCDN cannot acquire metadata, dCDN cannot aquire content, "dCDN
      Busy Tone" ) Recommendation: Try first specify what events and
      what information needs to be exchanged.  Depending on progress
      include in initial logging spec or not i.e.  handle as a [MED]
      requirement.

   o  Privacy: do we need some explicit support of IP address masking by
      dCDN to uCDN, or is it OK to assume that uCDN is to keep this info
      confidential (like dCDN is assumed to do already)?

   o  definition of field prefixes: add "r" is uCDN.  This one is less
      clear to me.  I need to see how you propose to use "r" below,
      before I can agree.  (Just for my own notes, I thought "r" could
      be used if the dCDN Surrogate was going to Log something related
      to acquisition of content by the dCDN Surrogate from some content
      source.  Also, in a delivery log generated by a dCDN Surrogate ,
      how can it know about acquisition from uCDN that can be done by
      other devices than the dCDN Surrogate).  "ucdn-centric-uri": ROB>
      going back to the definitions of s/c/r suggested above, for a CDNI
      logfile field would then just be "sr-uri".  So we don't need to
      invent a new prefix for CDNI, we can use the basic w3c naming?
      FRANCOIS: I am OK to use "sr-uri" as long as we feel confident
      that we will never need Surrogate to log information about how it
      acquires from within the dCDN (ie regular use of "r" prefix).  Are
      we confident?

   o  Do we need Record-Type as File Directive?: ROB> Is this needed -
      would a record type per file do the job?  ... if we don't allow
      mixed record types, we can include the record type in the ATOM
      feed (to allow the reader to decide whether there might be records
      it's interested in without getting the logfile).  I can't think of
      a reason to mix, (for example) http/rtmp records, or delivery/req-
      routing.  Different things are likely to be generating those
      records anyway.  A version change can always be done by starting a
      new file.  <Francois> Here are a couple potential use cases for
      mixing record types in a single file: * we later define
      "cdni_has_delivery_v1" record types for HTTP Adaptive BitRate
      sessions.  Then a dCDN Surrogate will be generating a continuous
      mixture of "cdni_http_request_v1" records for PDL requests and
      "cdni_has_request_v1" records for HAS sessions.  Why should we be
      forced to break those?  * we later define some record types for
      events taking place on Surrogates , which can happen any time in
      the middle of sessions.  Why shoudl we be forced to break those
      into separate files.  It seems wise to keep the flexibility in the
      File structure to allow the mix in the future.  And the overhead
      is very small since it is encoded in a Directive.





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   o  Integrity-Hash:ROB> draft-snell-atompub-link-extensions adds a
      hash of the resource to the ATOM feed (not sure about the status
      of that doc, looks like it's stalled a bit).  But if we include
      that in the ATOM feed, the value in the feed would need to include
      this Integrity-Hash in the log file itself, which might mean re-
      calculating the hash (especially if the feed is not generated in
      the same place as the logfile).  So we probably only want one of
      the two?  I think my preference would be to keep it in the feed,
      saves any complications about what to hash (just running "md5sum"
      on a downloaded logfile would work, rather than needing to remove
      the last line).  The draft-snell also allows other hashes, "sha1"
      and so on - for cdni interoperability, we could limit it to md5 or
      stick with draft-snell's base set.  <Francois> Very good point.  I
      agree we should probably want one of the two in a typical
      deployment.  Leveraging draft-snell-atompub-link-extensions is
      attractive because it leverages generic ATOM features and
      expertise.  It has the potential drawback of introducing a
      dependency on a document that may be published later (or
      potentially never since it is not even a WG doc).  Defining our
      own hash in the file is attractive because we can be done right
      away, and there could be simple short term implementation that
      start using the CDNI Logging File without relying on the ATOM
      Feed.  At the same time we don't want to end up with two redundant
      hashes eventually.  How about an approach where : * we define a
      simple MD5 has only, and make it optional * when there is no other
      mechanism to get the hash, it can be included in the file * when
      there are other mechanism (e.g.  draft-snell-atompub-link-
      extensions), it is not included in the file.

   o  Compression: <Ben>When we say the server MUST support gzip &
      deflate we probably need to think through whether we mean content-
      encoding, transfer-encoding or both.  The semantics get a little
      confusing so we probably just need to think them through to ensure
      we allow a server to store compressed logs as transmit them
      compressed.

6.  IANA Considerations

   TBD

7.  Security Considerations

7.1.  Authentication, Confidentiality, Integrity Protection

   The use of TLS for transport of the CDNI Logging feed mechanism
   (Section 4.1) and CDNI Logging File pull mechanism (Section 4.2)
   allows:




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   o  the dCDN and uCDN to authenticate each other (to ensure they are
      transmitting/receiving CDNI Logging File from an authenticated
      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.

   The Integrity-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.  This mechanism does not allow restoration of the
   corrupted CDNI Logging information, but it allows detection of such
   corruption and therefore triggering of appropraite correcting actions
   (e.g.  discard of corrupted information, attempt to re-obtain the
   CDNI Logging information).

7.2.  Non Repudiation

   The Non-Repudiation-Hash directive in the CDNI Logging File allows
   support of non-repudiation of the CDNI Logging File by the dCDN.  The
   optional Non-Repudiation-Hash can be used on the CDNI Logging
   interface where needed.

7.3.  Privacy

   CDNs have the opportunity to collect detailed information about the
   downloads performed by End-Users.  The provision of this information
   to another CDN introduces End-Users privacy protection concerns.
   [Editor's Note: see list of open questions]

8.  Acknowledgments

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

   The authors would like to thank Sebastien Cubaud, Pawel Grochocki,
   Christian Jacquenet, Yannick Le Louedec, Anne Marrec and Emile
   Stephan for their contributions on early versions of this document.

   The authors would like also to thank Rob Murray, Fabio Costa, Sara
   Oueslati, Yvan Massot, Renaud Edel, and Joel Favier for their input
   and comments.

   Finally, they thank the contributors of the EU FP7 OCEAN project for
   valuable inputs.




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9.  References

9.1.  Normative References

   [I-D.ietf-cdni-metadata]
              Niven-Jenkins, B., Murray, R., Watson, G., Caulfield, M.,
              Leung, K., and K. Ma, "CDN Interconnect Metadata", draft-
              ietf-cdni-metadata-01 (work in progress), February 2013.

   [RFC1321]  Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
              April 1992.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66, RFC
              3986, January 2005.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122, July
              2005.

   [RFC5424]  Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009.

9.2.  Informative References

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

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

   [I-D.brandenburg-cdni-has]
              Brandenburg, R., Deventer, O., Faucheur, F., and K. Leung,
              "Models for adaptive-streaming-aware CDN Interconnection",
              draft-brandenburg-cdni-has-05 (work in progress), April
              2013.

   [I-D.ietf-cdni-framework]





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              Peterson, L. and B. Davie, "Framework for CDN
              Interconnection", draft-ietf-cdni-framework-03 (work in
              progress), February 2013.

   [I-D.ietf-cdni-requirements]
              Leung, K. and Y. Lee, "Content Distribution Network
              Interconnection (CDNI) Requirements", draft-ietf-cdni-
              requirements-06 (work in progress), April 2013.

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

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

Appendix A.  Requirements

A.1.  Compliance with cdni-requirements

   This section checks that all the identified requirements in the
   Section 7 of [I-D.ietf-cdni-requirements] are fulfilled by this
   document.

   [Editor's node: to be written later]

A.2.  Additional Requirements

   This section identies additional requirements that must also be met.

   [Editor's node: How do we incorporate this info into the I-D: in
   appendix?  in main body?  does it remain after publication or is
   temporary?]

A.2.1.  Timeliness

   Some applications consuming CDNI Logging information, such as
   accounting or trend analytics, only require logging information to be
   available with a timeliness of the order of a day or the hour.  This
   document focuses on addressing this requirement.

   Some applications consuming CDNI Logging information, such as real-
   time analytics, require logging information to be available in real-
   time (i.e.  of the order of a second after the corresponding event).
   This document leaves this requirement out of scope.





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A.2.2.  Reliability

   CDNI logging information must be transmitted reliably.  The transport
   protocol should contain an anti-replay mechanism.

A.2.3.  Security

   CDNI logging information exchange must allow authentication,
   integrity protection, and confidentiality protection.  Also, a non-
   repudiation mechanism is mandatory, the transport protocol should
   support it.

A.2.4.  Scalability

   CDNI logging information exchange must support large scale
   information exchange, particularly so in the presence of HTTP
   Adaptive Streaming.

   For example, if we consider a client pulling HTTP Progressive
   Download content with an average duration of 10 minutes, this
   represents 1/600 CDNI delivery Logging Records per second.  If we
   assume the dCDN is simultaneously serving 100,000 such clients on
   behalf of the uCDN, the dCDN will be generating 167 Logging Records
   per second to be communicated to the uCDN over the CDNI Logging
   interface.  Or equivalently, if we assume an average delivery rate of
   2Mb/s, the dCDN generates 0.83 CDNI Logging Records per second for
   every Gb/s of streaming on behalf of the uCDN.

   For example, if we consider a client pulling HAS content and
   receiving a video chunk every 2 seconds, a separate audio chunck
   every 2 seconds and a refreshed manifest every 10 seconds, this
   represents 1.1 delivery Logging Record per second.  If we assume the
   dCDN is simultaneously serving 100,000 such clients on behalf of the
   uCDN, the dCDN will be generating 110,000 Logging Records per second
   to be communicated to the uCDN over the CDNI Logging interface.  Or
   equivalently, if we assume an average delivery rate of 2Mb/s, the
   dCDN generates 550 CDNI Logging Records per second for every Gb/s of
   streaming on behalf of the uCDN.

A.2.5.  Consistency between CDNI Logging and CDN Logging

   There are benefits in using a CDNI logging format as close as
   possible to intra-CDN logging format commonly used in CDNs today in
   order to minimize systematic translation at CDN/CDNI boundary.

A.2.6.  Dispatching/Filtering





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   When a CDN is acting as a dCDN for multiple uCDNs, the dCDN needs to
   dispatch each CDNI Logging Record to the uCDN that redirected the
   corresponding request.  The CDNI Logging format need to allow, and
   possibly facilitate, such a dispatching.

Appendix B.  Analysis of candidate protocols for Logging Transport

   This section will be expanded later with an analysis of alternative
   candidate protocols for transport of CDNI Logging in non-real-time as
   well as real-time.

B.1.  Syslog

   [Ed.  node: to be written later]

B.2.  XMPP

   [Ed.  node: to be written later]

B.3.  SNMP

Authors' Addresses

   Gilles Bertrand (editor)
   France Telecom - Orange
   38-40 rue du General Leclerc
   Issy les Moulineaux  92130
   FR

   Phone: +33 1 45 29 89 46
   Email: gilles.bertrand@orange.com


   Iuniana Oprescu (editor)
   France Telecom - Orange
   38-40 rue du General Leclerc
   Issy les Moulineaux  92130
   FR

   Phone: +33 6 89 06 92 72
   Email: iuniana.oprescu@orange.com










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   Francois Le Faucheur (editor)
   Cisco Systems
   E.Space Park - Batiment D
   6254 Allee des Ormes - BP 1200
   Mougins cedex  06254
   FR

   Phone: +33 4 97 23 26 19
   Email: flefauch@cisco.com


   Roy Peterkofsky
   Skytide, Inc.
   One Kaiser Plaza, Suite 785
   Oakland  CA 94612
   USA

   Phone: +01 510 250 4284
   Email: roy@skytide.com































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