Internet Engineering Task Force F. Le Faucheur, Ed.
Internet-Draft Cisco Systems
Intended status: Standards Track G. Bertrand, Ed.
Expires: March 31, 2014 I. Oprescu, Ed.
Orange
R. Peterkofsky
Skytide, Inc.
September 27, 2013
CDNI Logging Interface
draft-ietf-cdni-logging-06
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
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This Internet-Draft will expire on March 31, 2014.
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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
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 5
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 . . . . . . . . . . . . . 12
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 . . . . . . . . . . . . . . . . . . . . . . 15
3.1. Rules . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2. CDNI Logging File Structure . . . . . . . . . . . . . . . 16
3.3. CDNI Logging File Directives . . . . . . . . . . . . . . 18
3.4. CDNI Logging Records . . . . . . . . . . . . . . . . . . 21
3.4.1. HTTP Request Logging Record . . . . . . . . . . . . . 22
3.5. CDNI Logging File Example . . . . . . . . . . . . . . . . 29
4. CDNI Logging File Exchange Protocol . . . . . . . . . . . . . 30
4.1. CDNI Logging Feed . . . . . . . . . . . . . . . . . . . . 31
4.1.1. Atom Formatting . . . . . . . . . . . . . . . . . . . 31
4.1.2. Updates to Log Files and the Feed . . . . . . . . . . 32
4.1.3. Redundant Feeds . . . . . . . . . . . . . . . . . . . 32
4.1.4. Example CDNI Logging Feed . . . . . . . . . . . . . . 32
4.2. CDNI Logging File Pull . . . . . . . . . . . . . . . . . 33
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
5.1. CDNI Logging Directive Names Registry . . . . . . . . . . 34
5.2. CDNI Logging Record-Types Registry . . . . . . . . . . . 35
5.3. CDNI Logging Field Names Registry . . . . . . . . . . . . 35
5.4. CDNI Logging MIME Media Type . . . . . . . . . . . . . . 36
6. Security Considerations . . . . . . . . . . . . . . . . . . . 36
6.1. Authentication, Confidentiality, Integrity Protection . . 36
6.2. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 37
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7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 38
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 38
8.1. Normative References . . . . . . . . . . . . . . . . . . 38
8.2. Informative References . . . . . . . . . . . . . . . . . 39
Appendix A. Requirements . . . . . . . . . . . . . . . . . . . . 40
A.1. Compliance with cdni-requirements . . . . . . . . . . . . 40
A.1.1. General requirements . . . . . . . . . . . . . . . . 40
A.1.2. Logging Interface requirements . . . . . . . . . . . 40
A.1.3. Security requirements . . . . . . . . . . . . . . . . 42
A.2. Considerations on CDNI Logging Applicability . . . . . . 42
A.2.1. Timeliness . . . . . . . . . . . . . . . . . . . . . 42
A.2.2. Reliability . . . . . . . . . . . . . . . . . . . . . 42
A.2.3. Security . . . . . . . . . . . . . . . . . . . . . . 42
A.2.4. Scalability . . . . . . . . . . . . . . . . . . . . . 42
A.2.5. Consistency between CDNI Logging and CDN Logging . . 43
A.2.6. Dispatching/Filtering . . . . . . . . . . . . . . . . 43
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 43
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
[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:
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).
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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).
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
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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", "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 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.
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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 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.
This document 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 left for further study. This document specifies
exchange of logging information related to content delivery;
exchange of logging information related to operational events
(e.g. dCDN request routing function unavailable, content
acquisition failure by dCDN) for audit or operational reactive
adjustments by uCDN is outside the scope of the present document
and left for further study.
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 from 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:
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o to analyze the performance of the delivery operated by the dCDNs
and to adjust its operations a-posteriori (e.g., request routing)
as appropriate,
o to provide (non real-time) reporting and monitoring 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.
+-----+
| 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
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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.
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 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.
Log Consuming Log Consuming
App App
/\ /\
| |
Rectification--------
/\
|
Filtering
/\
|
Collection uCDN
/\ /\
| |
| Generation
|
CDNI Logging ---------------------------------------------
exchange
/\ Log Consuming Log Consuming
| App App
| /\ /\
| | |
Rectification Rectification---------
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/\ /\
| |
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
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).
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[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-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
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
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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.
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-
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chunk logs for that purpose (Content Collection IDentifier and a
Session IDentifier). However, in accordance with [RFC6983], 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
detection of configuration issues.
To detect faults, Logging must enable the reporting of any CDN
delivery operation success and failure. The uCDN can summarize such
information into KPIs. For instance, Logging needs to allow the
computation of the number of times, during a given time period, 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.
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
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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.
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
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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)
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.
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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
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
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
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].
The present document also defines the folowing additional rules:
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ADDRESS = IPv4address / IPv6address
DATE = 4DIGIT "-" 2DIGIT "-" 2DIGIT
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).
DEC = 1*DIGIT ["." *DIGIT]
QSTRING = DQUOTE *NDQUOTE DQUOTE ; where
NDQUOTE = <any OCTET excluding DQUOTE> / 2DQUOTE ; whereby a
DQUOTE is conveyed inside a QSTRING unambiguously by repeating
it.
NHTABSTRING = *NHTAB ; where
NHTAB = <any OCTET excluding HTAB>
TIME = 2DIGIT ":" 2DIGIT ":" 2DIGIT ["." *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).
3.2. CDNI Logging File Structure
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 use of a file structure for transfer of CDNI Logging information
is selected since this is the most common practise today for exchange
of logging information within and across CDNs.
+----------------------------------------------------------+
|CDNI Logging File |
| |
| #Directive 1 |
| #Directive 2 |
| ... |
| #Directive P |
| |
| +------------------------------------------------------+ |
| |CDNI Logging Record 1 | |
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| | +-------------+ +-------------+ +-------------+ | |
| | |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
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 CRLF.
Each line of a CDNI Logging File MUST contain either a directive or a
CDNI Logging Record.
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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 File structure is defined by the following rules:
DIRLINE = "#" directive CRLF
DIRGROUP = 1*DIRLINE
RECLINE = <CDNI Logging Record> CRLF
RECGROUP = *RECLINE
<CDNI Logging File> = 1*<DIRGROUP RECGROUP>
3.3. CDNI Logging File Directives
The CDNI Logging File directives are defined by the following rules:
directive = DIRNAME ":" HTAB DIRVAL
DIRNAME = any CDNI Logging Directive name registered in the CDNI
Logging Directive Names registry (Section 5.1).
DIRVAL = <directive value as specified below for each directive
name>
An implementation of the CDNI Logging interface MUST support all of
the following directives, listed below by their directive name:
o Version:
* format: "CDNI" "/" 1*DIGIT "." 1*DIGIT
* directive value: indicates the version of the CDNI Logging File
format. The value MUST be "CDNI/1.0" for the version specified
in the present document.
* occurrence: there MUST be one and only one instance of this
directive per CDNI Logging File. It MUST be the first line of
the CDNI Logging file.
o UUID:
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* format: NHTABSTRING
* directive value: this a Universally Unique IDentifier (UUID)
from the UUID Uniform Resource Name (URN) namespace specified
in [RFC4122]) for the CDNI Logging File .
* occurrence: there MUST be one and only one instance of this
directive per CDNI Logging File.
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).
* occurrence: there MUST be zero or one instance of this
directive per CDNI Logging File. This directive MAY be
included by the dCDN. It MUST NOT be included or modified by
the uCDN.
o Verified-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 one instance of this
directive per 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 CDNI Logging
File pull mechanism (Section 4.2).
o Record-Type:
* format: NHTABSTRING
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* directive value: 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). This can be any CDNI
Logging Record type registered in the CDNI Logging Record-types
registry (Section 5.2). "cdni_http_request_v1" MUST be
indicated as the Record-Type directive value for CDNI Logging
records corresponding to HTTP request (e.g. a HTTP delivery
request) as specified in Section 3.4.1.
* occurrence: there MUST be at least one instance of this
directive per CDNI Logging File. The first instance of this
directive MUST precede a Fields directive and precede any CDNI
Logging Record.
o Fields:
* format: FIENAME *<HTAB FIENAME> ; where FIENAME can take any
CDNI Logging field name registered in the CDNI Logging Field
Names registry (Section 5.3).
* 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). The names of the fields, as well as their
possible occurrences, are specified for each type of CDNI
Logging Records in Section 3.4.
* 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.
o Integrity-Hash:
* format: 32HEXDIG
* 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 filesystem of the dCDN Logging
system and leads to a truncation of a logging file. The valid
Integrity-Hash value is included in this directive by the
entity that transmits the CDNI Logging File. It is computed 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. The Integrity-Hash value
is represented as a US-ASCII encoded hexadecimal number, 32
digits long (representing a 128 bit hash value). The entity
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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 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. If the entity
receiving the CDNI Logging File adds a Verified-Origin
directive, it MUST recompute and update the Integrity-Hash
directive so it also protects the added Verified-Origin
directive.
* occurrence: there MUST be zero or one instance of this
directive. There SHOULD be 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 Logging Feed
Section 4.1 leveraging ATOM extensions such as those proposed
in [I-D.snell-atompub-link-extensions]. When present, this
field MUST be the last line of the CDNI Logging File.
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
is:
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 a uCDN)
o s: refers to the dCDN Surrogate that serves the request
(corresponds to the "server" of W3C Extended Log Format)
o u: refers to the uCDN (relative to a given CDN acting as a dCDN)
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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 Delivery Records as
specified in Section 3.4.1.
A CDNI Logging Record is defined by the following rules:
FIEVAL = <CDNI Logging Field value>
<CDNI Logging Record> = FIEVAL *<HTAB FIEVAL> ; where FIEVAL
contains the CDNI Logging field values corresponding to the CDNI
Logging field names (FIENAME) listed is the last Fields directive
predecing the present CDNI Logging Record.
3.4.1. HTTP Request Logging Record
The HTTP Request Logging Record is a CDNI Logging Record of Record-
Type "cdni_http_request_v1". It contains the following CDNI Logging
Fields, listed by their field name:
o date:
* format: DATE
* field value: the date at which the processing of request
completed on the Surrogate.
* occurrence: there MUST be one and only one instance of this
field.
o time:
* format: TIME
* field value: the time at which the processing of request
completed on the Surrogate.
* occurrence: there MUST be one and only one instance of this
field.
o time-taken:
* format: DEC
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* 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-ip:
* format: ADDRESS
* field value: 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-ip-anonimizing:
* format: 1*DIGIT
* field value: the number of rightmost bits of the address in the
c-ip field that are zeroed-out in order to anonymize the
logging record. The mechanism by which the two ends of the
CDNI Logging interface agree on whether anonimization is to be
supported and the number of bits that need to be zeroed-out for
this purpose are outside the scope of the present document.
* occurrence: there MUST be zero or one instance of this field.
o c-port:
* format: 1*DIGIT
* field value: 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
* field value: the IPv4 or IPv6 address of the Surrogate that
served the request (i.e. the "server" address).
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* 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.
* occurrence: there MUST be zero or exactly one instance of this
field.
o cs-method:
* format: NHTABSTRING
* field value: 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:
* format: NHTABSTRING
* field value: this is the complete URL of the request received
by the Surrogate. It is exactly in the format of a http_URL
specified in [RFC2616]) or, when the request was a HTTPS
request ([RFC2818]), it is in the format of a http_URL but with
the scheme part set to "https" instead of "http".
* occurrence: there MUST be zero or exactly one instance of this
field.
o u-uri:
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* format: NHTABSTRING
* field value: this is a complete URL, derived from the complete
URI 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.
* occurrence: there MUST be one and only one instance of this
field.
o protocol:
* format: NHTABSTRING
* field value: 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: 3DIGIT
* field value: 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: 1*DIGIT
* field value: 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.
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* 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
(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-name>):
* format: QSTRING
* field value: the value of the HTTP header (identified by the
<HTTP-header-name> in the CDNI Logging field name) as it
appears in the request processed by the Surrogate. For
example, when the CDNI Logging field name (FIENAME) listed in
the prededing 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.
* occurrence: there MUST be zero, one or any number of instance
of this field.
o sc(<HTTP-header-name>):
* format: QSTRING
* field value: the value of the HTTP header (identified by the
<HTTP-header-name> in the CDNI Logging 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: QSTRING
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* field value: this contains the value of the Content Collection
IDentifier associated by the uCDN to the content served by the
Surrogate via the CDNI Metadata interface
([I-D.ietf-cdni-metadata]).
* occurrence: 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
generated by the dCDN for a specific HTTP Adaptive Streaming
(HAS) session and whose 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.
* occurrence: there MUST be zero or exactly one instance of this
field.
o s-cached:
* format: 1DIGIT
* field value: this characterises whether the Surrogate served
the request using content already stored on its local cache or
not. The allowed values are "0" (for miss) and "1" (for hit).
"1" MUST be used when the Surrogate did 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.
The "Fields" directive corresponding to a HTTP Request Logging Record
MUST list all the fields name whose occurrence is specified above as
"There MUST be one and only one instance of this field". The
corresponding fields value MUST be present in every HTTP Request
Logging Record.
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The "Fields" directive corresponding to a HTTP Request Logging Record
MAY list all the fields value 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 name 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 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; in that case, if the value for the field is not
available, this MUST be conveyed via a dash character ("-").
The fields name 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.
A dCDN-side implementation of the CDNI Logging interface MUST support
the ability to include valid values for the following Logging Fields
in a CDNI Logging Record of Record-Type "cdni_http_request_v1":
o date
o time
o time-taken
o c-ip
o c-port
o s-ip
o s-hostname
o s-port
o cs- method
o cs-uri
o u-uri
o protocol
o sc-status
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o sc- total-bytes
o sc-entity-bytes
o cs(<HTTP-header>)
o sc(<HTTP-header>)
o s-ccid
o s-sid
o s-cached
A dCDN-side implementation of the CDNI Logging interface MAY support
the ability to include valid values for the following Logging Fields
in a CDNI Logging Record of Record-Type "cdni_http_request_v1":
o c-ip-anonimizing
o s-ccid
o s-sid
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.
3.5. CDNI Logging File Example
#Version:<HTAB>CDNI/1.0<CRLF>
#UUID:<HTAB>"urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6"<CRLF>
#Claimed-Origin:<HTAB>cdni-logging-entity.dcdn.example.com<CRLF>
#Record-Type:<HTAB>cdni_http_request_v1<CRLF>
#Fields:<HTAB>date<HTAB>time<TAB>time-taken<HTAB>c-ip<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>
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2013-05-17<HTAB>00:38:06.825<HTAB>9.058<HTAB>10.5.7.1<HTAB>GET<HTAB>h
ttp://cdni-ucdn.dcdn.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>10.5.10.5<HTAB>GET<HTAB>
http://cdni-ucdn.dcdn.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>10.5.10.5<HTAB>GET<HTAB
>http://cdni-ucdn.dcdn.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>
#Integrity-Hash: 9e107d9d372bb6826bd81d3542a419d6 [Editor's Note:
include the correct MD5-hash value for the actual example]<CRLF>
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.
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.
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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 mechanisms are outside the scope of the present
document but might be defined in future version of this document .
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. We define this MIME Media Type as "application/
cdni.LoggingFile" (See Section 5.4).
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.LoggingFile" MIME Media Type (See Section 5.4).
The IRI 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.
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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 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 SHOULD use HTTP cache control headers
on the subscription feed to indicate the frequency at which the
client-side is to poll for updates.
4.1.3. Redundant Feeds
The server-side implementation MAY present more than one CDNI Logging
feed and for redundancy, CDNI Logging files MAY be published in more
than one feed.
A client-side implementation MAY support such redundant CDNI Logging
feeds. If it supports redundant CDNI Logging feed, the client-side
SHOULD use the UUID of the CDNI Logging file, presented in the
atom:id element of the Atom feed, to avoid uncessarily pulling and
storing each CDNI Logging file more than once.
4.1.4. Example CDNI Logging Feed
Figure 4 illustrates an example of the subscription document of a
CDNI Logging feed.
<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom"
<http://www.w3.org/2005/Atom%22>>
<title type="text">CDNI Logging Feed</title>
<updated>2013-03-23T16:21:11Z</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>
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<title type="text">CDNI Logging File for uCDN at
2013-03-23 14:55:00</title>
<id>urn:uuid:12345678-1234-abcd-00aa-01234567abcd</id>
<updated>2013-03-23T14:55:00Z</updated>
<content src="https://dcdn.example/logs/ucdn/
http-requests-20130323145500000000"
type="application/cdni.LoggingFile" />
<summary>CDNI Logging File for uCDN at
2013-03-23 14:55:00</summary>
</entry>
<entry>
<title type="text">CDNI Logging File for uCDN at
2013-03-23 15:55:00</title>
<id>urn:uuid:87654321-4321-dcba-aa00-dcba7654321</id>
<updated>2013-03-23T15:55:00Z</updated>
<content src="https://dcdn.example/logs/ucdn/
http-requests-20130323155500000000"
type="application/cdni.LoggingFile" />
<summary>CDNI Logging File for uCDN at
2013-03-23 15:55:00</summary>
</entry>
...
<entry>
...
</entry>
</feed>
Figure 4: Example subscription document of a CDNI Logging Feed
4.2. CDNI Logging File Pull
A client-side implementation of the CDNI Logging interface MUST pull,
at its convenience, a CDNI Logging File that is published by the
server-side in the CDNI Logging Feed. To do so, the client-side:
o MUST use HTTP v1.1 ( [RFC2616])
o SHOULD use TLS (i.e. use what is loosely referred to as "HTTPS")
as per [RFC2818] whenever protection of the CDNI Logging
information is required (see Section 6.1)
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 uncompressed CDNI Logging Files (i.e.
using "identity" content coding as defined in [RFC2616])
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o SHOULD support exchange of gzip compressed CDNI Logging Files
(i.e. using "gzip" content coding as defined in [RFC2616])
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 published by the server-side in the subscription
document of CDNI Logging Feed.
[Editor's note: if a given Logging file is moved away from
subscription document to an archive document, do we agree it may no
longer be accessible to uCDN?]
The server-side implementation MUST respond to any valid pull request
by a client-side implementation for a CDNI Logging File published by
the server-side in the subscription document of 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 exchange of uncompressed CDNI Logging Files (i.e.
using "identity" content-coding as defined in [RFC2616])
o SHOULD support exchange of gzip compressed CDNI Logging Files
(i.e. using "gzip" content-coding as defined in [RFC2616]
Content negotiation approaches defined in [RFC2616] (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.
5. IANA Considerations
5.1. CDNI Logging Directive Names Registry
The IANA is requested to create a new registry, CDNI Logging
Directive Names.
The initial contents of the CDNI Logging File Directives registry
comprise the names of the directives specified in Section 3.3 of the
present document, and are as follows:
+------------------------------+-----------+
+ Directive Name + Reference |
+------------------------------+-----------+
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+ Version + RFC xxxx |
+ UUID + RFC xxxx |
+ Claimed-Origin + RFC xxxx |
+ Verified-Origin + RFC xxxx |
+ Record-Type + RFC xxxx |
+ Fields + RFC xxxx |
+ Integrity-Hash + RFC xxxx |
+------------------------------+-----------+
Figure 5
[Instructions to IANA: Replace "RFC xxxx" above by the RFC number of
the present document]
Within the registry, names are to be allocated by IANA according to
the "Specification Required" policy specified in [RFC5226].
5.2. CDNI Logging Record-Types Registry
The IANA is requested to create a new registry, CDNI Logging Record-
Types.
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 |
+------------------------------+-----------+
+ cdni_http_request_v1 + RFC xxxx |
+------------------------------+-----------+
Figure 6
[Instructions to IANA: Replace "RFC xxxx" above by the RFC number of
the present document]
Within the registry, Record-Types are to be allocated by IANA
according to the "Specification Required" policy specified in
[RFC5226].
5.3. CDNI Logging Field Names Registry
The IANA is requested to create a new registry, CDNI Logging Field
Names.
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The initial contents of the CDNI Logging Fields Names registry
comprise the names of the CDNI Logging fields specified in
Section 3.4 of the present document, and are as follows:
+---------------------------------------------+-----------+
+ Field Name + Reference |
+---------------------------------------------+-----------+
+ date + RFC xxxx |
+ time + RFC xxxx |
+ time-taken + RFC xxxx |
+ c-ip + RFC xxxx |
+ c-ip-anonimizing + RFC xxxx |
+ c-port + RFC xxxx |
+ s-ip + RFC xxxx |
+ s-hostname + RFC xxxx |
+ s-port + RFC xxxx |
+ cs- method + RFC xxxx |
+ cs-uri + RFC xxxx |
+ u-uri + RFC xxxx |
+ protocol + RFC xxxx |
+ sc-status + RFC xxxx |
+ sc- total-bytes + RFC xxxx |
+ sc-entity-bytes + RFC xxxx |
+ cs(<HTTP-header>) + RFC xxxx |
+ sc(<HTTP-header>) + RFC xxxx |
+ s-ccid + RFC xxxx |
+ s-sid + RFC xxxx |
+ s-cached + RFC xxxx |
+---------------------------------------------+-----------+
Figure 7
[Instructions to IANA: Replace "RFC xxxx" above by the RFC number of
the present document]
Within the registry, names are to be allocated by IANA according to
the "Specification Required" policy specified in [RFC5226].
5.4. CDNI Logging MIME Media Type
The IANA is requested to allocate the "application/cdni.LoggingFile"
MIME Media Type (whose use is specified in Section 4.1.1 of the
present document) in the MIME Media Types registry.
6. Security Considerations
6.1. Authentication, Confidentiality, Integrity Protection
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The use of TLS as per [RFC2818] for transport of the CDNI Logging
feed mechanism (Section 4.1) and CDNI Logging File pull mechanism
(Section 4.2) allows:
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
In an environment where any such protection is required, TLS SHOULD
be used for transport of the CDNI Logging feed and the CDNI Logging
File pull.
A CDNI Logging implementation MUST support TLS transport of the CDNI
Logging feed and the CDNI Logging File pull.
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).
6.2. 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 potential End-Users privacy protection
concerns. We observe that when CDNI interconnection is realised as
per [I-D.ietf-cdni-framework], the uCDN handles the initial End-User
requests (before it is redirected to the dCDN) so, regardless of
which information is, or is not, communicated to the uCDN through the
CDNI Logging interface, the uCDN has visibility on significant
information such as the IP address of the End-User request and the
URL of the request. Nonetheless, if the dCDN and uCDN agree that
anonymization is required to avoid making some detailed information
available to the uCDN (such as how much bytes of the content has been
watched by an enduser and/or at what time) or is required to meet
some legal obligations, then the uCDN and dCDN can agree to exchange
anonymized End-User IP addresses in CDNI Logging files and the c-ip-
anonymization field can be used to convey the number of bits that
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have been anonymized so that the meaningful information can still be
easily extracted from the anonymized addressses (e.g. for geolocation
aware analytics).
7. Acknowledgments
This document borrows from the W3C Extended Log Format [ELF].
Rob Murray significantly contributed into the text of Section 4.1 .
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 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.
8. References
8.1. Normative References
[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.
[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
Syndication Format", RFC 4287, December 2005.
[RFC5005] Nottingham, M., "Feed Paging and Archiving", RFC 5005,
September 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
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[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
8.2. 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.ietf-cdni-framework]
Peterson, L. and B. Davie, "Framework for CDN
Interconnection", draft-ietf-cdni-framework-05 (work in
progress), September 2013.
[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-02 (work in progress), July 2013.
[I-D.ietf-cdni-requirements]
Leung, K. and Y. Lee, "Content Distribution Network
Interconnection (CDNI) Requirements", draft-ietf-cdni-
requirements-10 (work in progress), September 2013.
[I-D.snell-atompub-link-extensions]
Snell, J., "Atom Link Extensions", draft-snell-atompub-
link-extensions-09 (work in progress), June 2012.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[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.
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[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, July 2013.
Appendix A. Requirements
[Editor's Note: text in this Appendix will be revisited soon]
A.1. Compliance with cdni-requirements
This section discusses compliance of the present specification
against all the relevant requirements of
[I-D.ietf-cdni-requirements].
[Editor's Note: we may want to re-structure this into a table that
would more clearly show compliance level]
A.1.1. General requirements
Some of the general CDNI requirements defined in
[I-D.ietf-cdni-requirements] are not applicable to the CDNI Logging
Interface [GEN-5, GEN-6, GEN-7, GEN-8, GEN-9, GEN-12].
The Logging Interface does not define any new protocols [GEN-1], does
not require any change or upgrade on the user agent [GEN-2] or on the
Content Service Provider side [GEN-3]. Also, no intra-CDN
information is necessary [GEN-4] and the CDNI Logging Interface
supports any interconnection topology [GEN-10]. However, The CDNI
Logging Interface does not define a specific loop avoidance mechanism
[GEN-11], but the exchange of logs is usually done in a point to
point manner between two well identified entities situated
respectively in the uCDN and the dCDN.
The CDNI Loggin Interface supports specific logging for the HTTP
Adaptive Streaming content. [RFC6983] offers more details about
particular logging fields required for HTTP Adaptive Streaming.
A.1.2. Logging Interface requirements
Reliable transfer is achieved by the transport protocol: the logging
information is transmitted over HTTP running over TCP [LI-1].
The CDNI Logging Interface supports logs for all content deliveries
both complete and incomplete performed by the dCDN on behalf of the
uCDN [LI-2].
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The CDNI Logging Interface does not impose any restrictions related
to the transmission of logs generated by intermediary CDNs. The dCDN
formats internally all the final logging files, including those
received from intermediary CDNs and the files locally generated. The
dCDN then sends all required logging files to the uCDN [LI-3].
The ATOM feed allows the uCDN to trigger the download of logging
files whenever needed [LI-4].
The uCDN can pull logging files from the dCDN whenever a new file is
available. The timing constraints for the generation of the logging
files are to be defined offline, since the CDNI Logging Interface
does not include a negotiation mechanism for the frequency of logging
file generation. Note that the current version of this document
refers strictly to non real-time logging [LI-5].
Section Section 3.4 describes the CDNI Logging Records and the
possible fields that can be included in a record [LI-6].
As a transport mechanism, the CDNI Logging Interface uses the ATOM
protocol over HTTP (or HTTPS) [LI-7].
A CDN can query another CDN for relevant current logging files by
using the ATOM feed that allows to check for newly published content.
Note that the current version of this document refers strictly to non
real-time logging [LI-8].
The current version of the document does not specify any mechanisms
for producing aggregate / summarized logs, but the exchanged logging
files provide all information that is necessary to the uCDN in order
to obtain aggregated logs. Future versions might include such
mechanisms [LI-9].
No logging of performance data or consumed resources for the dCDN
itself or any other cascaded CDN is included in the current version
of the document. Future versions of this document might define such
information [LI-10, LI-11, LI-12].
The current version of the document specifies the logging information
related strictly to the delivery process. Logging files for any
other functionalities (e.g., content purge, request routing events
etc.) might be taken into account in future versions [LI-13].
Extensibility, the logging and exchange of proprietary information
fields are detailed in Section 5 IANA Considerations [LI-14, LI-15].
The ATOM protocol allows the dCDN to publish the list of available
resources (i.e. logging files) [LI-16].
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Section 3.4 provides details about the fields of the HTTP Adaptive
Streaming specific logging records, including the Content Collection
Identifier (s-ccid) and Session Identifier (s-sid) [LI-17].
A.1.3. Security requirements
[SEC-3, SEC-5] are not applicable to the CDNI Loggin Interface, all
remaining security requirements are addressed as discussed in
Section 6.
A.2. Considerations on CDNI Logging Applicability
This section discusses a number of considerations related to the
applicability of the CDNI Logging interface as specified in the
present document.
[Editor's note: 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.
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.
A.2.4. Scalability
CDNI logging information exchange must support large scale
information exchange, particularly so in the presence of HTTP
Adaptive Streaming.
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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
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.
Authors' Addresses
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
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Gilles Bertrand (editor)
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)
Orange
38-40 rue du General Leclerc
Issy les Moulineaux 92130
FR
Phone: +33 6 89 06 92 72
Email: iuniana.oprescu@orange.com
Roy Peterkofsky
Skytide, Inc.
One Kaiser Plaza, Suite 785
Oakland CA 94612
USA
Phone: +01 510 250 4284
Email: roy@skytide.com
Le Faucheur, et al. Expires March 31, 2014 [Page 44]