Content Distribution Network Interconnection (CDNI) Logging Interface
RFC 7937
| Document | Type | RFC - Proposed Standard (August 2016) | |
|---|---|---|---|
| Authors | François Le Faucheur , Gilles Bertrand , Iuniana Oprescu , Roy Peterkofsky | ||
| Last updated | 2016-08-29 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews |
GENART Last Call review
(of
-15)
Almost Ready
SECDIR Last Call review
(of
-15)
Has Issues
OPSDIR Early review
(of
-11)
Has Issues
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Kevin J. Ma | ||
| Shepherd write-up | Show Last changed 2015-02-04 | ||
| IESG | IESG state | RFC 7937 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | Spencer Dawkins | ||
| Send notices to | "Kevin J. Ma" <kevin.j.ma@ericsson.com> | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack |
RFC 7937
Internet Engineering Task Force (IETF) F. Le Faucheur, Ed.
Request for Comments: 7937
Category: Standards Track G. Bertrand, Ed.
ISSN: 2070-1721
I. Oprescu, Ed.
R. Peterkofsky
Google Inc.
August 2016
Content Distribution Network Interconnection (CDNI) Logging Interface
Abstract
This memo specifies the Logging interface between a downstream
Content Distribution Network (dCDN) and an upstream CDN (uCDN) that
are interconnected as per the CDN Interconnection (CDNI) framework.
First, it describes a reference model for CDNI logging. Then, it
specifies the CDNI Logging File format and the actual protocol for
exchange of CDNI Logging Files.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7937.
Le Faucheur, et al. Standards Track [Page 1]
RFC 7937 CDNI Logging August 2016
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. CDNI Logging Reference Model . . . . . . . . . . . . . . . . 5
2.1. CDNI Logging Interactions . . . . . . . . . . . . . . . . 5
2.2. Overall Logging Chain . . . . . . . . . . . . . . . . . . 9
2.2.1. Logging Generation and During-Generation Aggregation 10
2.2.2. Logging Collection . . . . . . . . . . . . . . . . . 11
2.2.3. Logging Filtering . . . . . . . . . . . . . . . . . . 11
2.2.4. Logging Rectification and Post-Generation Aggregation 12
2.2.5. Log-Consuming Applications . . . . . . . . . . . . . 13
2.2.5.1. Maintenance and Debugging . . . . . . . . . . . . 13
2.2.5.2. Accounting . . . . . . . . . . . . . . . . . . . 14
2.2.5.3. Analytics and Reporting . . . . . . . . . . . . . 14
2.2.5.4. Content Protection . . . . . . . . . . . . . . . 14
2.2.5.5. Notions Common to Multiple Log-Consuming
Applications . . . . . . . . . . . . . . . . . . 15
3. CDNI Logging File . . . . . . . . . . . . . . . . . . . . . . 17
3.1. Rules . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2. CDNI Logging File Structure . . . . . . . . . . . . . . . 18
3.3. CDNI Logging Directives . . . . . . . . . . . . . . . . . 21
3.4. CDNI Logging Records . . . . . . . . . . . . . . . . . . 26
3.4.1. HTTP Request Logging Record . . . . . . . . . . . . . 27
3.5. CDNI Logging File Extension . . . . . . . . . . . . . . . 38
3.6. CDNI Logging File Examples . . . . . . . . . . . . . . . 38
3.7. Cascaded CDNI Logging Files Example . . . . . . . . . . . 42
Le Faucheur, et al. Standards Track [Page 2]
RFC 7937 CDNI Logging August 2016
4. Protocol for Exchange of CDNI Logging File after Full
Collection . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.1. CDNI Logging Feed . . . . . . . . . . . . . . . . . . . . 45
4.1.1. Atom Formatting . . . . . . . . . . . . . . . . . . . 45
4.1.2. Updates to Log Files and the Feed . . . . . . . . . . 46
4.1.3. Redundant Feeds . . . . . . . . . . . . . . . . . . . 47
4.1.4. Example CDNI Logging Feed . . . . . . . . . . . . . . 47
4.2. CDNI Logging File Pull . . . . . . . . . . . . . . . . . 49
5. Protocol for Exchange of CDNI Logging File During Collection 50
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 51
6.1. CDNI Logging Directive Names Registry . . . . . . . . . . 51
6.2. CDNI Logging File version Registry . . . . . . . . . . . 51
6.3. CDNI Logging record-types Registry . . . . . . . . . . . 52
6.4. CDNI Logging Field Names Registry . . . . . . . . . . . . 53
6.5. CDNI Logging Payload Type . . . . . . . . . . . . . . . . 55
7. Security Considerations . . . . . . . . . . . . . . . . . . . 55
7.1. Authentication, Authorization, Confidentiality, and
Integrity Protection . . . . . . . . . . . . . . . . . . 55
7.2. Denial of Service . . . . . . . . . . . . . . . . . . . . 56
7.3. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 57
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.1. Normative References . . . . . . . . . . . . . . . . . . 58
8.2. Informative References . . . . . . . . . . . . . . . . . 61
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 63
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 63
1. Introduction
This memo specifies the CDNI Logging interface between a downstream
CDN (dCDN) and an upstream CDN (uCDN). First, it describes a
reference model for CDNI logging. Then, it specifies the CDNI
Logging File format and the actual protocol for exchange of CDNI
Logging Files.
The reader should be familiar with the following documents:
o CDNI problem statement [RFC6707] and framework [RFC7336], which
identify a Logging interface,
o Section 8 of [RFC7337], which specifies a set of requirements for
Logging,
o [RFC6770] outlines real world use cases for interconnecting CDNs.
These use cases require the exchange of Logging information
between the dCDN and the uCDN.
Le Faucheur, et al. Standards Track [Page 3]
RFC 7937 CDNI Logging August 2016
As stated in [RFC6707], "the CDNI Logging interface enables details
of content distribution and delivery activities to be exchanged
between interconnected CDNs."
The present document describes:
o The CDNI Logging reference model (Section 2)
o The CDNI Logging File format (Section 3)
o The CDNI Logging File Exchange protocol (Section 4)
1.1. Terminology
In this document, the first letter of each CDNI-specific term is
capitalized. We adopt the terminology described in [RFC6707] and
[RFC7336], and extend it with the additional terms defined below.
Intra-CDN Logging information: Logging information generated and
collected within a CDN. The format of the Intra-CDN Logging
information may be different from the format of the CDNI Logging
information.
CDNI Logging information: Logging information exchanged across CDNs
using the CDNI Logging interface.
Logging information: Logging information generated and collected
within a CDN or obtained from another CDN using the CDNI Logging
interface.
CDNI Logging Field: An atomic element of information that can be
included in a CDNI Logging Record. The time an event/task started,
the IP address of an end user to whom content was delivered, and the
Uniform Resource Identifier (URI) of the content delivered, are
examples of CDNI Logging fields.
CDNI Logging Record: An information record providing information
about a specific event. This comprises a collection of CDNI Logging
fields.
CDNI Logging File: A file containing CDNI Logging Records, as well as
additional information facilitating the processing of the CDNI
Logging Records.
CDN Reporting: The process of providing the relevant information that
will be used to create a formatted content delivery report provided
to the Content Service Provider (CSP) in deferred time. Such
information typically includes aggregated data that can cover a large
Le Faucheur, et al. Standards Track [Page 4]
RFC 7937 CDNI Logging August 2016
period of time (e.g., from hours to several months). Uses of
reporting include the collection of charging data related to CDN
services and the computation of Key Performance Indicators (KPIs).
CDN Monitoring: The process of providing or displaying content
delivery information in a timely fashion with respect to the
corresponding deliveries. Monitoring typically includes visibility
of the deliveries in progress for service operation purposes. It
presents a view of the global health of the services as well as
information on usage and performance, for network services
supervision and operation management. In particular, monitoring data
can be used to generate alarms.
1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119].
2. CDNI Logging Reference Model
2.1. CDNI Logging Interactions
The CDNI logging reference model between a given uCDN and a given
dCDN involves the following interactions:
o customization by the uCDN of the CDNI Logging information to be
provided by the dCDN to the uCDN (e.g., control of which CDNI
Logging fields are to be communicated to the uCDN for a given task
performed by the dCDN or control of which types of events are to
be logged). The dCDN takes into account this CDNI Logging
customization information to determine what Logging information to
provide to the uCDN, but it may, or may not, take into account
this CDNI Logging customization information to influence what CDN
Logging information is to be generated and collected within the
dCDN (e.g., even if the uCDN requests a restricted subset of the
Logging information, the dCDN may elect to generate a broader set
of Logging information). The mechanism to support the
customization by the uCDN of CDNI Logging information is outside
the scope of this document and is left for further study. Until
such a mechanism is available, the uCDN and dCDN are expected to
agree off-line on what exact set of CDNI Logging information is to
be provided by the dCDN to the uCDN, and to rely on management-
plane actions to configure the CDNI Logging functions in the dCDN
to generate this information set and in the uCDN to expect this
information set.
Le Faucheur, et al. Standards Track [Page 5]
RFC 7937 CDNI Logging August 2016
o generation and collection by the dCDN of the intra-CDN Logging
information related to the completion of any task performed by the
dCDN on behalf of the uCDN (e.g., delivery of the content to an
end user) or related to events happening in the dCDN that are
relevant to the uCDN (e.g., failures or unavailability in dCDN).
This takes place within the dCDN and does not directly involve
CDNI interfaces.
o communication by the dCDN to the uCDN of the Logging information
collected by the dCDN relevant to the uCDN. This is supported by
the CDNI Logging interface and is in the scope of the present
document. For example, the uCDN may use this Logging information
to charge the CSP, to perform analytics and monitoring for
operational reasons, to provide analytics and monitoring views on
its content delivery to the CSP, or to perform troubleshooting.
This document exclusively specifies non-real-time exchange of
Logging information. Closer to real-time exchange of Logging
information (say sub-minute or sub-second) is outside the scope of
the present document and is left for further study. This document
exclusively specifies exchange of Logging information related to
content delivery. Exchange of Logging information related to
operational events (e.g., dCDN request routing function
unavailable and content acquisition failure by dCDN) for audit or
operational reactive adjustments by uCDN is outside the scope of
the present document and is left for further study.
o customization by the dCDN of the CDNI Logging information to be
provided by the uCDN on behalf of the dCDN. The mechanism to
support the customization by the dCDN of CDNI Logging information
is outside the scope of this document and is left for further
study.
o generation and collection by the uCDN of Intra-CDN Logging
information related to the completion of any task performed by the
uCDN on behalf of the dCDN (e.g., serving of content by uCDN to
dCDN for acquisition purposes by dCDN) or related to events
happening in the uCDN that are relevant to the dCDN. This takes
place within the uCDN and does not directly involve CDNI
interfaces.
o communication by the uCDN to the dCDN of the Logging information
collected by the uCDN relevant to the dCDN. For example, the dCDN
might potentially benefit from this information for security
auditing or content acquisition troubleshooting. This is outside
the scope of this document and is left for further study.
Le Faucheur, et al. Standards Track [Page 6]
RFC 7937 CDNI Logging August 2016
Figure 1 provides an example of CDNI Logging interactions (focusing
only on the interactions that are in the scope of this document) in a
particular scenario where four CDNs are involved in the delivery of
content from a given CSP: the uCDN has a CDNI interconnection with
dCDN-1 and dCDN-2. In turn, dCDN-2 has a CDNI interconnection with
dCDN-3, where dCDN-2 is acting as an upstream CDN relative to dCDN-3.
In this example, uCDN, dCDN-1, dCDN-2, and dCDN-3 all participate in
the delivery of content for the CSP. In this example, the CDNI
Logging interface enables the uCDN to obtain Logging information from
all the dCDNs involved in the delivery. In the example, the uCDN
uses the Logging information:
o to analyze the performance of the delivery performed by the dCDNs
and to adjust its operations after the fact (e.g., request
routing) as appropriate.
o to provide (non-real-time) reporting and monitoring information to
the CSP.
For instance, the uCDN merges Logging information, extracts relevant
KPIs, and presents a formatted report to the CSP, in addition to a
bill for the content delivered by uCDN itself or by its dCDNs on the
CSP's behalf. The uCDN may also provide Logging information as raw
log files to the CSP, so that the CSP can use its own logging
analysis tools.
Le Faucheur, et al. Standards Track [Page 7]
RFC 7937 CDNI Logging August 2016
+-----+
| CSP |
+-----+
^ Reporting and monitoring data
* Billing
,--*--.
Logging ,-' `-.
Data =>( uCDN )<= Logging
// `-. _,-' \\ Data
|| `-'-'-' ||
,-----. ,-----.
,-' `-. ,-' `-.
( dCDN-1 ) ( dCDN-2 )<== Logging
`-. ,-' `-. _,-' \\ Data
`--'--' `--'-' ||
,-----.
,' `-.
( dCDN-3 )
`. ,-'
`--'--'
===> CDNI Logging interface
***> outside the scope of CDNI
Figure 1: Interactions in the CDNI Logging Reference Model
A downstream CDN relative to uCDN (e.g., dCDN-2) integrates the
relevant Logging information obtained from its own downstream CDNs
(i.e., dCDN-3) in the Logging information that it provides to the
uCDN, so that the uCDN ultimately obtains all Logging information
relevant to a CSP for which it acts as the authoritative CDN. Such
aggregation is further discussed in Section 3.7.
Note that the format of Logging information that a CDN provides over
the CDNI interface might be different from the one that the CDN uses
internally. In this case, the CDN needs to reformat the Logging
information before it provides this information to the other CDN over
the CDNI Logging interface. Similarly, a CDN might reformat the
Logging information that it receives over the CDNI Logging interface
before injecting it into its log-consuming applications or before
providing some of this Logging information to the CSP. Such
reformatting operations introduce latency in the logging distribution
chain and introduce a processing burden. Therefore, there are
benefits in specifying CDNI Logging formats that are suitable for use
inside CDNs and also are close to the intra-CDN Logging formats
commonly used in CDNs today.
Le Faucheur, et al. Standards Track [Page 8]
RFC 7937 CDNI Logging August 2016
2.2. Overall Logging Chain
This section discusses the overall logging chain within and across
CDNs to clarify how CDN Logging information is expected to fit in
this overall chain. Figure 2 illustrates the overall logging chain
within the dCDN, across CDNs using the CDNI Logging interface, and
within the uCDN. Note that the logging chain illustrated in the
figure is obviously only an example and varies depending on the
specific environments. For example, there may be more or fewer
instantiations of each entity (e.g., there may be 4 log-consuming
applications in a given CDN). As another example, there may be one
instance of a Rectification process per log-consuming application
instead of a shared one.
Le Faucheur, et al. Standards Track [Page 9]
RFC 7937 CDNI Logging August 2016
Log-Consuming Log-Consuming
App App
^ ^
| |
Rectification----------
^
|
Filtering
^
|
Collection
^ ^
| |
| Generation
|
| uCDN
CDNI Logging ---------------------------------------------------
exchange dCDN
^
| Log-Consuming Log-Consuming
| App App
| ^ ^
| | |
Rectification Rectification---------
^ ^
| |
Filtering
^
|
Collection
^ ^
| |
Generation Generation
Figure 2: CDNI Logging in the Overall Logging Chain
The following subsections describe each of the processes potentially
involved in the logging chain of Figure 2.
2.2.1. Logging Generation and During-Generation Aggregation
CDNs typically generate Logging information for all significant task
completions, events, and failures. Logging information is typically
generated by many devices in the CDN including the surrogates, the
request routing system, and the control system.
Le Faucheur, et al. Standards Track [Page 10]
RFC 7937 CDNI Logging August 2016
The amount of Logging information generated can be huge. Therefore,
during contract negotiations, interconnected CDNs often agree on a
retention duration for Logging information, and/or potentially on a
maximum volume of Logging information that the dCDN ought to keep.
If this volume is exceeded, the dCDN is expected to alert the uCDN
but may not keep more Logging information for the considered time
period. In addition, CDNs may aggregate Logging information and
transmit only summaries for some categories of operations instead of
the full Logging information. Note that such aggregation leads to an
information loss, which may be problematic for some usages of the
Logging information (e.g., debugging).
[RFC6983] discusses logging for HTTP Adaptive Streaming (HAS). In
accordance with the recommendations articulated there, it is expected
that a surrogate will generate separate Logging information for
delivery of each chunk of HAS content. This ensures that separate
Logging information can then be provided to interconnected CDNs over
the CDNI Logging interface. Still in line with the recommendations
of [RFC6983], the Logging information for per-chunk delivery may
include some information (a Content Collection IDentifier and a
Session IDentifier) intended to facilitate subsequent post-generation
aggregation of per-chunk logs into per-session logs. Note that a CDN
may also elect to generate aggregate per-session logs when performing
HAS delivery, but this needs to be in addition to, and not instead
of, the per-chunk delivery logs. We note that aggregate per-session
logs for HAS delivery are for further study and are outside the scope
of this document.
2.2.2. Logging Collection
This is the process that continuously collects Logging information
generated by the log-generating entities within a CDN.
In a CDNI environment, in addition to collecting Logging information
from log-generating entities within the local CDN, the Collection
process also collects Logging information provided by another CDN, or
other CDNs, through the CDNI Logging interface. This is illustrated
in Figure 2 where we see that the Collection process of the uCDN
collects Logging information from log-generating entities within the
uCDN as well as Logging information coming from the dCDNs through the
CDNI Logging interface.
2.2.3. Logging Filtering
A CDN may be required to only present different subsets of the whole
Logging information collected to various log-consuming applications.
This is achieved by the Filtering process.
Le Faucheur, et al. Standards Track [Page 11]
RFC 7937 CDNI Logging August 2016
In particular, the Filtering process can also filter the right subset
of Logging information that needs to be provided to a given
interconnected CDN. For example, the filtering process in the dCDN
can be used to ensure that only the Logging information related to
tasks performed on behalf of a given uCDN are made available to that
uCDN (thereby filtering out all the Logging information related to
deliveries by the dCDN of content for its own CSPs). Similarly, the
Filtering process may filter or partially mask some fields, for
example, to protect end-users' privacy when communicating CDNI
Logging information to another CDN. Filtering of Logging information
prior to communication of this information to other CDNs via the CDNI
Logging interface requires that the downstream CDN can recognize the
subset of Logging information that relates to each interconnected
CDN.
The CDN will also filter some internal scope information such as
information related to its internal alarms (security, failures, load,
etc.).
In some use cases described in [RFC6770], the interconnected CDNs do
not want to disclose details on their internal topology. The
filtering process can then also filter confidential data on the
dCDNs' topology (number of servers, location, etc.). In particular,
information about the requests served by each Surrogate may be
confidential. Therefore, the Logging information needs to be
protected so that data such as the Surrogates' hostnames are not
disclosed to the uCDN. In the "Inter-Affiliates Interconnection" use
case, this information may be disclosed to the uCDN because both the
dCDN and the uCDN are operated by entities of the same group.
2.2.4. Logging Rectification and Post-Generation Aggregation
If Logging information is generated periodically, it is important
that the sessions that start in one Logging period and end in another
are correctly reported. If they are reported in the starting period,
then the Logging information of this period will be available only
after the end of the session, which delays the Logging information
generation. A simple approach is to provide the complete Logging
Record for a session in the Logging Period of the session end.
A Logging rectification/update mechanism could be useful to reach a
good trade-off between the Logging information generation delay and
the Logging information accuracy.
In the presence of HAS, some log-consuming applications can benefit
from aggregate per-session logs. For example, for analytics, per-
session logs allow display of session-related trends, which are much
more meaningful for some types of analysis than chunk-related trends.
Le Faucheur, et al. Standards Track [Page 12]
RFC 7937 CDNI Logging August 2016
In the case where aggregate logs have been generated directly by the
log-generating entities, those can be used by the applications. In
the case where aggregate logs have not been generated, the
Rectification process can be extended with a Post-Generation
Aggregation process that generates per-session logs from the per-
chunk logs, possibly leveraging the information included in the per-
chunk logs for that purpose (Content Collection IDentifier and a
Session IDentifier). However, in accordance with [RFC6983], this
document does not define the exchange of such aggregate logs on the
CDNI Logging interface. We note that this is for further study and
is outside the scope of this document.
2.2.5. Log-Consuming Applications
2.2.5.1. Maintenance and Debugging
Logging information is useful to permit the detection (and limit the
risk) of content delivery failures. In particular, Logging
information facilitates the detection of configuration issues.
To detect faults, Logging information needs to report the success and
failure of CDN-delivery operations. The uCDN can summarize such
information into KPIs. For instance, Logging information needs to
allow the computation of the number of times, during a given time
period, that content delivery related to a specific service succeeds
or fails.
Logging information enables the CDN providers to identify and
troubleshoot performance degradations. In particular, Logging
information enables tracking of traffic data (e.g., the amount of
traffic that has been forwarded by a dCDN on behalf of an uCDN over a
given period of time), which is particularly useful for CDN and
network planning operations.
Some of these maintenance and debugging applications only require
aggregate Logging information highly compatible with the use of
anonymization of IP addresses (as supported by the present document
and specified in the definition of the c-groupid field in
Section 3.4.1). However, in some situations, it may be useful, where
compatible with privacy protection, to access some CDNI Logging
Records containing full non-anonymized IP addresses. This is allowed
in the definition of the c-groupid (in Section 3.4.1), with very
significant privacy protection limitations that are discussed in the
definition of the c-groupid field. For example, this may be useful
for detailed fault tracking of a particular end-user content delivery
issue. Where there is a hard requirement by uCDN or CSP to associate
a given end user to individual CDNI Logging Records (e.g., to allow a
posteriori analysis of individual delivery, for example, in
Le Faucheur, et al. Standards Track [Page 13]
RFC 7937 CDNI Logging August 2016
situations of performance-based penalties), instead of using
aggregates containing a single client as discussed in the c-groupid
field definition, an alternate approach is to ensure that a client
identifier is embedded in the request fields that can be logged in a
CDNI Logging Record (for example, by including the client identifier
in the URI query string or in an HTTP Header). That latter approach
offers two significant benefits: first, the aggregate inside the
c-groupid can contain more than one client, thereby ensuring stronger
privacy protection; second, it allows a reliable identification of
the client while IP address does not in many situations (e.g., behind
NAT, where dynamic IP addresses are used and reused, etc.). However,
care SHOULD be taken so that the client identifiers exposed in other
fields of the CDNI Records cannot themselves be linked back to actual
users.
2.2.5.2. Accounting
Logging information is essential for accounting, to permit inter-CDN
billing and CSP billing by uCDNs. For instance, Logging information
provided by dCDNs enables the uCDN to compute the total amount of
traffic delivered by every dCDN for a particular Content Provider, as
well as the associated bandwidth usage (e.g., peak, 95th percentile),
and the maximum number of simultaneous sessions over a given period
of time.
2.2.5.3. Analytics and Reporting
The goals of analytics include gathering any relevant information in
order to be able to develop statistics on content download, analyze
user behavior, and monitor the performance and quality of content
delivery. For instance, Logging information enables the CDN
providers to report on content consumption (e.g., delivered sessions
per content) in a specific geographic area.
The goal of reporting is to gather any relevant information to
monitor the performance and quality of content delivery, and allow
detection of delivery issues. For instance, reporting could track
the average delivery throughput experienced by end users in a given
region for a specific CSP or content set over a period of time.
2.2.5.4. Content Protection
The goal of content protection is to prevent and monitor unauthorized
access, misuse, modification, and denial of access to content. A set
of information is logged in a CDN for security purposes. In
particular, a record of access to content is usually collected to
permit the CSP to detect infringements of content delivery policies
and other abnormal end-user behaviors.
Le Faucheur, et al. Standards Track [Page 14]
RFC 7937 CDNI Logging August 2016
2.2.5.5. Notions Common to Multiple Log-Consuming Applications
2.2.5.5.1. Logging Information Views
Within a given log-consuming application, different views may be
provided to different users depending on privacy, business, and
scalability constraints.
For example, an analytics tool run by the uCDN can provide one view
to a uCDN operator that exploits all the Logging information
available to the uCDN, while the tool may provide a different view to
each CSP exploiting only the Logging information related to the
content of the given CSP.
As another example, maintenance and debugging tools may provide
different views to different CDN operators, based on their
operational role.
2.2.5.5.2. Key Performance Indicators (KPIs)
This section presents, for explanatory purposes, a non-exhaustive
list of Key Performance Indicators (KPIs) that can be extracted/
produced from logs.
Multiple log-consuming applications, such as analytics, monitoring,
and maintenance applications, often compute and track such KPIs.
In a CDNI environment, depending on the situation, these KPIs may be
computed by the uCDN or by the dCDN. But it is usually the uCDN that
computes KPIs, because the uCDN and dCDN may have different
definitions of the KPIs and the computation of some KPIs requires a
vision of all the deliveries performed by the uCDN and all its dCDNs.
Here is a list of important examples of KPIs:
o Number of delivery requests received from end users in a given
region for each piece of content, during a given period of time
(e.g., hour/day/week/month)
o Percentage of delivery successes/failures among the aforementioned
requests
o Number of failures listed by failure type (e.g., HTTP error code)
for requests received from end users in a given region and for
each piece of content, during a given period of time (e.g.,
hour/day/week/month)
Le Faucheur, et al. Standards Track [Page 15]
RFC 7937 CDNI Logging August 2016
o Number and cause of premature delivery termination for end users
in a given region and for each piece of content, during a given
period of time (e.g., hour/day/week/month)
o Maximum and mean number of simultaneous sessions established by
end users in a given region, for a given Content Provider, and
during a given period of time (e.g., hour/day/week/month)
o Volume of traffic delivered for sessions established by end users
in a given region, for a given Content Provider, and during a
given period of time (e.g., hour/day/week/month)
o Maximum, mean, and minimum delivery throughput for sessions
established by end users in a given region, for a given Content
Provider, and during a given period of time (e.g., hour/day/week/
month)
o Cache-hit and byte-hit ratios for requests received from end users
in a given region for each piece of content, during a given period
of time (e.g., hour/day/week/month)
o Top 10 most popularly requested contents (during a given day/week/
month)
o Terminal type (mobile, PC, Set-Top Box (STB), if this information
can be acquired from the browser type inferred from the User Agent
string, for example)
Additional KPIs can be computed from other sources of information
than the Logging information, for instance, data collected by a
content portal or by specific client-side application programming
interfaces. Such KPIs are out of scope for the present document.
The KPIs used depend strongly on the considered log-consuming
application -- the CDN operator may be interested in different
metrics than the CSP. In particular, CDN operators are often
interested in delivery and acquisition performance KPIs, information
related to Surrogates' performance, caching information to evaluate
the cache-hit ratio, information about the delivered file size to
compute the volume of content delivered during peak hour, etc.
Some of the KPIs, for instance those providing an instantaneous
vision of the active sessions for a given CSP's content, are useful
essentially if they are provided in a timely manner. By contrast,
some other KPIs, such as those averaged over a long period of time,
can be provided in non-real-time.
Le Faucheur, et al. Standards Track [Page 16]
RFC 7937 CDNI Logging August 2016
3. CDNI Logging File
3.1. Rules
This specification uses the Augmented Backus-Naur Form (ABNF)
notation and core rules of [RFC5234]. In particular, the present
document uses the following rules from [RFC5234]:
CR = %x0D ; carriage return
ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
DIGIT = %x30-39 ; 0-9
DQUOTE = %x22 ; " (Double Quote)
CRLF = CR LF ; Internet standard newline
HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
HTAB = %x09 ; horizontal tab
LF = %x0A ; linefeed
VCHAR = %x21-7E ; visible (printing) characters
OCTET = %x00-FF ; 8 bits of data
The present document also uses the following rules from [RFC3986]:
host = as specified in Section 3.2.2 of [RFC3986].
IPv4address = as specified in Section 3.2.2 of [RFC3986].
IPv6address = as specified in Section 3.2.2 of [RFC3986].
partial-time = as specified in Section 5.6 of [RFC3339].
The present document also defines the following additional rules:
ADDRESS = IPv4address / IPv6address
ALPHANUM = ALPHA / DIGIT
DATE = 4DIGIT "-" 2DIGIT "-" 2DIGIT
; Dates are encoded as "full-date" specified in [RFC3339].
Le Faucheur, et al. Standards Track [Page 17]
RFC 7937 CDNI Logging August 2016
DEC = 1*DIGIT ["." 1*DIGIT]
NAMEFORMAT = ALPHANUM *(ALPHANUM / "_" / "-")
QSTRING = DQUOTE *(NDQUOTE / PCT-ENCODED) DQUOTE
NDQUOTE = %x20-21 / %x23-24 / %x26-7E / UTF8-2 / UTF8-3 / UTF8-4
; whereby a DQUOTE is conveyed inside a QSTRING unambiguously
; by escaping it with PCT-ENCODED.
PCT-ENCODED = "%" HEXDIG HEXDIG
; percent encoding is used for escaping octets that might be
; possible in HTTP headers such as bare CR, bare LF, CR LF,
; HTAB, SP, or null. These octets are rendered with percent
; encoding in ABNF as specified by [RFC3986] in order to avoid
; considering them as separators for the Logging Records.
NHTABSTRING = 1*(SP / VCHAR)
TIME = partial-time
USER-COMMENT = *(SP / VCHAR / UTF8-2 / UTF8-3 / UTF8-4)
3.2. CDNI Logging File Structure
As defined in Section 1.1, a CDNI Logging Field is an atomic Logging
information element, a CDNI Logging Record is a collection of CDNI
Logging fields containing all logging information corresponding to a
single logging event, and a CDNI Logging File contains a collection
of CDNI Logging Records. This structure is illustrated in Figure 3.
The use of a file structure for transfer of CDNI Logging information
is selected since this is the most common practice today for exchange
of Logging information within and across CDNs.
Le Faucheur, et al. Standards Track [Page 18]
RFC 7937 CDNI Logging August 2016
+----------------------------------------------------------+
|CDNI Logging File |
| |
| #Directive 1 |
| #Directive 2 |
| ... |
| #Directive P |
| |
| +------------------------------------------------------+ |
| |CDNI Logging Record 1 | |
| | +-------------+ +-------------+ +-------------+ | |
| | |CDNI Logging | |CDNI Logging | ... |CDNI Logging | | |
| | | Field 1 | | Field 2 | | Field N | | |
| | +-------------+ +-------------+ +-------------+ | |
| +------------------------------------------------------+ |
| |
| +------------------------------------------------------+ |
| |CDNI Logging Record 2 | |
| | +-------------+ +-------------+ +-------------+ | |
| | |CDNI Logging | |CDNI Logging | ... |CDNI Logging | | |
| | | Field 1 | | Field 2 | | Field N | | |
| | +-------------+ +-------------+ +-------------+ | |
| +------------------------------------------------------+ |
| |
| ... |
| |
| #Directive P+1 |
| |
| ... |
| |
| +------------------------------------------------------+ |
| |CDNI Logging Record M | |
| | +-------------+ +-------------+ +-------------+ | |
| | |CDNI Logging | |CDNI Logging | ... |CDNI Logging | | |
| | | Field 1 | | Field 2 | | Field N | | |
| | +-------------+ +-------------+ +-------------+ | |
| +------------------------------------------------------+ |
| |
| |
| #Directive P+Q |
+----------------------------------------------------------+
Figure 3: Structure of Logging Files
Le Faucheur, et al. Standards Track [Page 19]
RFC 7937 CDNI Logging August 2016
The CDNI Logging File format is inspired from the W3C Extended Log
File Format [ELF]. However, it is fully specified by the present
document. Where the present document differs from the W3C Extended
Log File Format, an implementation of the CDNI Logging interface MUST
comply with the present document. The W3C Extended Log File Format
was used as a starting point, reused where possible, and expanded
when necessary.
Using a format that resembles the W3C Extended Log File Format is
intended to keep the CDNI logging format close to the intra-CDN
Logging information format commonly used in CDNs today, thereby
minimizing systematic translation at the CDN/CDNI boundary.
A CDNI Logging File MUST contain a sequence of lines containing US-
ASCII characters [CHAR_SET] terminated by CRLF. Each line of a CDNI
Logging File MUST contain either a directive or a CDNI Logging
Record.
Directives record information about the CDNI Logging process itself.
Lines containing directives MUST begin with the "#" character.
Directives are specified in Section 3.3.
Logging Records provide actual details of the logged event. Logging
Records are specified in Section 3.4.
The CDNI Logging File has a specific structure. It always starts
with a directive line, and the first directive it contains MUST be
the version.
The directive lines form together a group that contains at least one
directive line. Each directives group is followed by a group of
Logging Records. The records group contains zero or more actual
Logging Record lines about the event being logged. A record line
consists of the values corresponding to all or a subset of the
possible Logging fields defined within the scope of the record-type
directive. These values MUST appear in the order defined by the
fields directive.
Note that future extensions MUST be compliant with the previous
description. The following examples depict the structure of a
CDNILOGFILE as defined currently by the record-type
"cdni_http_request_v1."
Le Faucheur, et al. Standards Track [Page 20]
RFC 7937 CDNI Logging August 2016
DIRLINE = "#" directive CRLF
DIRGROUP = 1*DIRLINE
RECLINE = <any subset of record values that match what is expected
according to the fields directive within the immediately preceding
DIRGROUP>
RECGROUP = *RECLINE
CDNILOGFILE = 1*(DIRGROUP RECGROUP)
3.3. CDNI Logging Directives
A CDNI Logging directive line contains the directive name followed by
":" HTAB and the directive value.
Directive names MUST be of the format NAMEFORMAT. All directive
names MUST be registered in the "CDNI Logging Directives Names"
registry. Directive names are case-insensitive as per the basic ABNF
([RFC5234]). Unknown directives MUST be ignored. Directive values
can have various formats. All possible directive values for the
record-type "cdni_http_request_v1" are further detailed in this
section.
The following example shows the structure of a directive and
enumerates strictly the directive values presently defined in the
version "cdni/1.0" of the CDNI Logging File.
directive = DIRNAME ":" HTAB DIRVAL
DIRNAME = NAMEFORMAT
FIENAME = <any CDNI Logging field name registered in the CDNI
Logging Field Names registry (Section 6.4) that is valid for the
record type specified in the record-type directive.>
DIRVAL = NHTABSTRING / QSTRING / host / USER-COMMENT / FIENAME
*(HTAB FIENAME) / 64HEXDIG
Le Faucheur, et al. Standards Track [Page 21]
RFC 7937 CDNI Logging August 2016
An implementation of the CDNI Logging interface MUST support all of
the following directives, listed below by their directive name:
o Version:
* Format: NHTABSTRING
* Directive value: Indicates the version of the CDNI Logging File
format. The entity transmitting a CDNI Logging File as per the
present document MUST set the value to "cdni/1.0". In the
future, other versions of the CDNI Logging File might be
specified; those would use a value different from "cdni/1.0",
which allows the entity receiving the CDNI Logging File to
identify the corresponding version. CDNI Logging File versions
are case-insensitive as per the basic ABNF ([RFC5234]).
* Occurrence: There MUST be one and only one instance of this
directive per the CDNI Logging File. It MUST be the first line
of the CDNI Logging File.
* Example: "version: HTAB cdni/1.0".
o UUID:
* Format: NHTABSTRING
* Directive value: This a Uniform Resource Name (URN) from the
Universally Unique IDentifier (UUID) URN namespace specified in
[RFC4122]. The UUID contained in the URN uniquely identifies
the CDNI Logging File.
* Occurrence: There MUST be one and only one instance of this
directive per the CDNI Logging File.
* Example: "UUID: HTAB NHTABSTRING".
o Claimed-origin:
* Format: Host
* Directive value: This contains the claimed identification of
the entity transmitting the CDNI Logging File (e.g., the host
in a dCDN supporting the CDNI Logging interface) or the entity
responsible for transmitting the CDNI Logging File (e.g., the
dCDN).
Le Faucheur, et al. Standards Track [Page 22]
RFC 7937 CDNI Logging August 2016
* Occurrence: There MUST be zero or exactly one instance of this
directive per the CDNI Logging File. This directive MAY be
included by the dCDN. It MUST NOT be included or modified by
the uCDN.
* Example: "claimed-origin: HTAB host".
o Established-origin:
* Format: Host
* Directive value: This contains the identification, as
established by the entity receiving the CDNI Logging File, of
the entity transmitting the CDNI Logging File (e.g., the host
in a dCDN supporting the CDNI Logging interface) or the entity
responsible for transmitting the CDNI Logging File (e.g., the
dCDN).
* Occurrence: There MUST be zero or exactly one instance of this
directive per the CDNI Logging File. This directive MAY be
added by the uCDN (e.g., before storing the CDNI Logging File).
It MUST NOT be included by the dCDN. The mechanisms used by
the uCDN to establish and validate the entity responsible for
the CDNI Logging File is outside the scope of the present
document. We observe that, in particular, this may be achieved
through authentication mechanisms that are part of the
transport layer of the CDNI Logging File pull mechanism
(Section 4.2).
* ABNF example: "established-origin: HTAB host".
o Remark:
* Format: USER-COMMENT
* Directive value: This contains comment information. Data
contained in this field is to be ignored by analysis tools.
* Occurrence: There MAY be zero, one, or any number of instances
of this directive per the CDNI Logging File.
* Example: "remark: HTAB USER-COMMENT".
Le Faucheur, et al. Standards Track [Page 23]
RFC 7937 CDNI Logging August 2016
o Record-type:
* Format: NAMEFORMAT
* Directive value: Indicates the type of the CDNI Logging Records
that follow this directive, until another record-type directive
appears in the CDNI Logging File (or the end of the CDNI
Logging File). This can be any CDNI Logging Record type
registered in the "CDNI Logging record-types" registry
(Section 6.3). For example, this may be "cdni_http_request_v1"
as specified in Section 3.4.1. CDNI Logging record-types are
case-insensitive as per the basic ABNF ([RFC5234]).
* Occurrence: There MUST be at least one instance of this
directive per the CDNI Logging File. The first instance of
this directive MUST precede a fields directive and MUST precede
all CDNI Logging Records.
* Example: "record-type: HTAB cdni_http_request_v1".
o Fields:
* Format: FIENAME *(HTAB FIENAME) ; where FIENAME can take any
CDNI Logging field name registered in the "CDNI Logging Field
Names" registry (Section 6.4) that is valid for the record type
specified in the record-type directive.
* Directive value: This lists the names of all the fields for
which a value is to appear in the CDNI Logging Records that
follow the instance of this directive (until another instance
of this directive appears in the CDNI Logging File). The names
of the fields, as well as their occurrences, MUST comply with
the corresponding rules specified in the document referenced in
the "CDNI Logging record-types" registry (Section 6.3) for the
corresponding CDNI Logging record-type.
* Occurrence: There MUST be at least one instance of this
directive per record-type directive. The first instance of
this directive for a given record-type MUST appear before any
CDNI Logging Record for this record-type. One situation where
more than one instance of the fields directive can appear
within a given CDNI Logging File is when there is a change, in
the middle of a fairly large logging period, and in the
agreement between the uCDN and the dCDN about the set of fields
that are to be exchanged. The multiple occurrences allow
records with the old set of fields and records with the new set
of fields to be carried inside the same Logging File.
Le Faucheur, et al. Standards Track [Page 24]
RFC 7937 CDNI Logging August 2016
* Example: "fields: HTAB FIENAME * (HTAB FIENAME)".
o SHA256-hash:
* Format: 64HEXDIG
* Directive value: This directive permits the detection of a
corrupted CDNI Logging File. This can be useful, for instance,
if a problem occurs on the file system of the dCDN Logging
system and leads to a truncation of a Logging File. The valid
SHA256-hash value is included in this directive by the entity
that transmits the CDNI Logging File. It MUST be computed by
applying the SHA-256 ([RFC6234]) cryptographic hash function on
the CDNI Logging File, including all the directives and Logging
Records, up to the SHA256-hash directive itself, excluding the
SHA256-hash directive itself. The SHA256-hash value MUST be
represented as a 64-digit hexadecimal number encoded in US-
ASCII (representing a 256 bit hash value). The entity
receiving the CDNI Logging File also computes, in a similar
way, the SHA-256 hash on the received CDNI Logging File and
compares this hash to the value of the SHA256-hash directive.
If the two values are equal, then the received CDNI Logging
File is to be considered non-corrupted. If the two values are
different, the received CDNI Logging File is to be considered
corrupted. The behavior of the entity that received a
corrupted CDNI Logging File is outside the scope of this
specification; we note that the entity MAY attempt to pull the
same CDNI Logging File from the transmitting entity again. If
the entity receiving a non-corrupted CDNI Logging File adds an
established-origin directive, it MUST then recompute and update
the SHA256-hash directive so that it also protects the added
established-origin directive.
* Occurrence: There MUST be zero or exactly one instance of this
directive. There SHOULD be exactly one instance of this
directive. One situation where that directive could be omitted
is where integrity protection is already provided via another
mechanism (for example, if an integrity hash is associated to
the CDNI Logging File out of band through the CDNI Logging Feed
(Section 4.1) leveraging ATOM extensions such as those proposed
in [ATOMPUB]. When present, the SHA256-hash field MUST be the
last line of the CDNI Logging File.
* Example: "SHA256-hash: HTAB 64HEXDIG".
A uCDN-side implementation of the CDNI Logging interface MUST ignore
a CDNI Logging File that does not comply with the occurrences
specified above for each and every directive. For example, a uCDN-
Le Faucheur, et al. Standards Track [Page 25]
RFC 7937 CDNI Logging August 2016
side implementation of the CDNI Logging interface receiving a CDNI
Logging File with zero occurrence of the version directive, or with
two occurrences of the SHA256-hash, MUST ignore this CDNI Logging
File.
An entity receiving a CDNI Logging File with a value set to
"cdni/1.0" MUST process the CDNI Logging File as per the present
document. An entity receiving a CDNI Logging File with a value set
to a different value MUST process the CDNI Logging File as per the
specification referenced in the "CDNI Logging File version" registry
(see Section 6.1) if the implementation supports this specification
and MUST ignore the CDNI Logging File otherwise.
3.4. CDNI Logging Records
A CDNI Logging Record consists of a sequence of CDNI Logging fields
relating to that single CDNI Logging Record.
CDNI Logging fields MUST be separated by the horizontal tabulation
(HTAB) character.
To facilitate readability, a prefix scheme is used for CDNI Logging
field names in a similar way to the one used in W3C Extended Log File
Format [ELF]. The semantics of the prefix in the present document
are:
o "c-" refers to the User Agent that issues the request (corresponds
to the "client" of W3C Extended Log Format)
o "d-" refers to the dCDN (relative to a given CDN acting as an
uCDN)
o "s-" refers to the dCDN Surrogate that serves the request
(corresponds to the "server" of the W3C Extended Log Format)
o "u-" refers to the uCDN (relative to a given CDN acting as a dCDN)
o "cs-" refers to communication from the User Agent towards the dCDN
Surrogate
o "sc-" refers to communication from the dCDN Surrogate towards the
User Agent
An implementation of the CDNI Logging interface as per the present
specification MUST support the CDNI HTTP Request Logging Record as
specified in Section 3.4.1.
Le Faucheur, et al. Standards Track [Page 26]
RFC 7937 CDNI Logging August 2016
A CDNI Logging Record contains the corresponding values for the
fields that are enumerated in the last fields directive before the
current log line. Note that the order in which the field values
appear is dictated by the order of the fields names in the fields
directive. There SHOULD be no dependency between the various fields
values.
3.4.1. HTTP Request Logging Record
This section defines the CDNI Logging Record of record-type
"cdni_http_request_v1". It is applicable to content delivery
performed by the dCDN using HTTP/1.0 ([RFC1945]), HTTP/1.1 ([RFC7230]
[RFC7231] [RFC7232] [RFC7233] [RFC7234] [RFC7235]), or HTTPS
([RFC2818] [RFC7230]). We observe that, in the case of HTTPS
delivery, there may be value in logging additional information
specific to the operation of HTTP over Transport Layer Security (TLS)
and we note that this is outside the scope of the present document
and may be addressed in a future document defining another CDNI
Logging Record or another version of the HTTP Request Logging Record.
The "cdni_http_request_v1" record-type is also expected to be
applicable to HTTP/2 [RFC7540] since a fundamental design tenet of
HTTP/2 is to preserve the HTTP/1.1 semantics. We observe that, in
the case of HTTP/2 delivery, there may be value in logging additional
information specific to the additional functionality of HTTP/2 (e.g.,
information related to connection identification, to stream
identification, to stream priority, and to flow control). We note
that such additional information is outside the scope of the present
document and may be addressed in a future document defining another
CDNI Logging Record or another version of the HTTP Request Logging
Record.
The "cdni_http_request_v1" record-type contains the following CDNI
Logging fields, listed by their field name:
o Date:
* Format: DATE
* Field value: The date on which the processing of the request
completed on the Surrogate.
* Occurrence: There MUST be one and only one instance of this
field.
Le Faucheur, et al. Standards Track [Page 27]
RFC 7937 CDNI Logging August 2016
o Time:
* Format: TIME
* Field value: The time, which MUST be expressed in Coordinated
Universal Time (UTC), at which the processing of the request
completed on the Surrogate.
* Occurrence: There MUST be one and only one instance of this
field.
o Time-taken:
* Format: DEC
* Field value: Decimal value of the duration, in seconds, between
the start of the processing of the request and the completion
of the request processing (e.g., completion of delivery) by the
Surrogate.
* Occurrence: There MUST be one and only one instance of this
field.
o c-groupid:
* Format: NHTABSTRING
* Field value: An opaque identifier for an aggregate set of
clients, derived from the client IPv4 or IPv6 address in the
request received by the Surrogate and/or other network-level
identifying information. The c-groupid serves to group clients
into aggregates. Example aggregates include civil geolocation
information (the country, second-level administrative division,
or postal code from which the client is presumed to make the
request based on a geolocation database lookup) or network
topological information (e.g., the BGP autonomous system (AS)
number announcing the prefix containing the address). The
c-groupid MAY be structured, e.g., US/TN/MEM/38138. Agreement
between the dCDN and the uCDN on a mapping between IPv4 and
IPv6 addresses and aggregates is presumed to occur out of band.
The aggregation mapping SHOULD be chosen such that each
aggregate contains more than one client.
+ When the aggregate is chosen so that it contains a single
client (e.g., to allow more detailed analytics, or to allow
a posteriori analysis of individual delivery, for example,
in situations of performance-based penalties), the c-groupid
MAY be structured where some elements identify aggregates
Le Faucheur, et al. Standards Track [Page 28]
RFC 7937 CDNI Logging August 2016
and one element identifies the client, e.g.,
US/TN/MEM/38138/43a5bdd6-95c4-4d62-be65-7410df0021e2. In
the case where the aggregate is chosen so that it contains a
single client:
- The element identifying the client SHOULD be
algorithmically generated (from the client IPv4 or IPv6
address in the request received by the Surrogate and/or
other network-level identifying information) in a way
that SHOULD NOT be linkable back to the global addressing
context and that SHOULD vary over time (to offer
protection against long-term attacks).
- It is RECOMMENDED that the mapping varies at least once
every 24 hours.
- The algorithmic mapping and variation over time can, in
some cases, allow the uCDN (with the knowledge of the
algorithm, the time variation, and the associated
attributes and keys) to reconstruct the actual client
IPv4 or IPv6 address and/or other network-level
identifying information when required (e.g., to allow a
posteriori analysis of individual delivery, for example,
in situations of performance-based penalties). However,
these end-user addresses SHOULD only be reconstructed on-
demand and the CDNI Logging File SHOULD only be stored
with the anonymized c-groupid value.
- Allowing reconstruction of client address information
carries with it grave risks to end-user privacy. Since
the c-groupid is, in this case, equivalent in
identification power to a client IP address, its use may
be restricted by regulation or law as personally
identifiable information. For this reason, such use is
NOT RECOMMENDED.
- One method for mapping that MAY be supported by
implementations relies on a symmetric key that is known
only to the uCDN, the dCDN, and the HMAC-based Extract-
and-Expand Key Derivation Function (HKDF) key derivation
([RFC5869]), as will be used in TLS 1.3 ([TLS-1.3]).
When that method is used:
o The uCDN and dCDN need to agree on the "salt" and
"input keying material", as described in Section 2.2
of [RFC5869] and the initial "info" parameter (which
could be something like the business names of the two
organizations in UTF-8, concatenated), as described in
Le Faucheur, et al. Standards Track [Page 29]
RFC 7937 CDNI Logging August 2016
Section 2.3 of [RFC5869]. The hash SHOULD be either
SHA-2 or SHA-3 [SHA-3], and the encryption algorithm
SHOULD be 128-bit AES [AES] in Galois Counter Mode
(GCM) [GCM] (AES-GCM) or better. The pseudorandom key
(PRK) SHOULD be chosen by both parties contributing
alternate random bytes until sufficient length exists.
After the initial setup, client-information can be
encrypted using the key generated by the "expand" step
of Section 2.3 of [RFC5869]. The encrypted value
SHOULD be hex encoded or base64 encoded (as specified
in Section 4 of [RFC4648]). At the agreed-upon
expiration time, a new key SHOULD be generated and
used. New keys SHOULD be indicated by prefixing the
key with a special character such as an exclamation
point. In this way, shorter lifetimes can be used as
needed.
* Occurrence: There MUST be one and only one instance of this
field.
o s-ip:
* Format: ADDRESS
* Field value: The IPv4 or IPv6 address of the Surrogate that
served the request (i.e., the "server" address).
* Occurrence: There MUST be zero or exactly one instance of this
field.
o s-hostname:
* Format: Host
* Field value: The hostname of the Surrogate that served the
request (i.e., the "server" hostname).
* Occurrence: There MUST be zero or exactly one instance of this
field.
o s-port:
* Format: 1*DIGIT
* Field value: The destination TCP port (i.e., the "server" port)
in the request received by the Surrogate.
Le Faucheur, et al. Standards Track [Page 30]
RFC 7937 CDNI Logging August 2016
* Occurrence: There MUST be zero or exactly one instance of this
field.
o cs-method:
* Format: NHTABSTRING
* Field value: This is the method of the request received by the
Surrogate. In the case of HTTP delivery, this is the HTTP
method in the request.
* Occurrence: There MUST be one and only one instance of this
field.
o cs-uri:
* Format: NHTABSTRING
* Field value: This is the "effective request URI" of the request
received by the Surrogate as specified in [RFC7230]. It
complies with the "http" URI scheme or the "https" URI scheme
as specified in [RFC7230]. Note that cs-uri can be privacy
sensitive. In that case, and where appropriate, u-uri could be
used instead of cs-uri.
* Occurrence: There MUST be zero or exactly one instance of this
field.
o u-uri:
* Format: NHTABSTRING
* Field value: This is a complete URI, derived from the
"effective request URI" ([RFC7230]) of the request received by
the Surrogate (i.e., the cs-uri) but transformed by the entity
generating or transmitting the CDNI Logging Record, in a way
that is agreed upon between the two ends of the CDNI Logging
interface, so the transformed URI is meaningful to the uCDN.
For example, the two ends of the CDNI Logging interface could
agree that the u-uri is constructed from the cs-uri by removing
the part of the hostname that exposes which individual
Surrogate actually performed the delivery. The details of
modification performed to generate the u-uri, as well as the
mechanism to agree on these modifications between the two sides
of the CDNI Logging interface are outside the scope of the
present document.
Le Faucheur, et al. Standards Track [Page 31]
RFC 7937 CDNI Logging August 2016
* Occurrence: There MUST be one and only one instance of this
field.
o Protocol:
* Format: NHTABSTRING
* Field value: This is the value of the HTTP-Version field as
specified in [RFC7230] of the Request-Line of the request
received by the Surrogate (e.g., "HTTP/1.1").
* Occurrence: There MUST be one and only one instance of this
field.
o sc-status:
* Format: 3DIGIT
* Field value: This is the Status-Code in the response from the
Surrogate. In the case of HTTP delivery, this is the HTTP
Status-Code in the HTTP response.
* Occurrence: There MUST be one and only one instance of this
field.
o sc-total-bytes:
* Format: 1*DIGIT
* Field value: This is the total number of bytes of the response
sent by the Surrogate in response to the request. In the case
of HTTP delivery, this includes the bytes of the Status-Line,
the bytes of the HTTP headers, and the bytes of the message-
body.
* Occurrence: There MUST be one, and only one, instance of this
field.
o sc-entity-bytes:
* Format: 1*DIGIT
* Field value: This is the number of bytes of the message-body in
the HTTP response sent by the Surrogate in response to the
request. This does not include the bytes of the Status-Line or
the bytes of the HTTP headers.
Le Faucheur, et al. Standards Track [Page 32]
RFC 7937 CDNI Logging August 2016
* Occurrence: There MUST be zero or exactly one instance of this
field.
o cs(insert_HTTP_header_name_here):
* Format: QSTRING
* Field value: The value of the HTTP header (identified by the
insert_HTTP_header_name_here in the CDNI Logging field name) as
it appears in the request processed by the Surrogate, but
prepended by a DQUOTE and appended by a DQUOTE. For example,
when the CDNI Logging field name (FIENAME) listed in the
preceding fields directive is cs(User-Agent), this CDNI Logging
field value contains the value of the User-Agent HTTP header as
received by the Surrogate in the request it processed, but
prepended by a DQUOTE and appended by a DQUOTE. If the HTTP
header, as it appeared in the request processed by the
Surrogate, contains one or more DQUOTE, each DQUOTE MUST be
escaped with percent encoding. For example, if the HTTP header
contains My_Header"value", then the field value of the
cs(insert_HTTP_header_name_here) is "My_Header%x22value%x22".
The entity transmitting the CDNI Logging File MUST ensure that
the respective insert_HTTP_header_name_here of the
cs(insert_HTTP_header_name_here) listed in the fields directive
comply with HTTP specifications. In particular, this field
name does not include any HTAB, since this would prevent proper
parsing of the fields directive by the entity receiving the
CDNI Logging File.
* Occurrence: There MAY be zero, one, or any number of instance
of this field.
o sc(insert_HTTP_header_name_here):
* Format: QSTRING
* Field value: The value of the HTTP header (identified by the
insert_HTTP_header_name_here in the CDNI Logging field name) as
it appears in the response issued by the Surrogate to serve the
request, but prepended by a DQUOTE and appended by a DQUOTE.
If the HTTP header, as it appeared in the request processed by
the Surrogate, contains one or more DQUOTEs, each DQUOTE MUST
be escaped with percent encoding. For example, if the HTTP
header contains My_Header"value", then the field value of the
sc(insert_HTTP_header_name_here) is "My_Header%x22value%x22".
The entity transmitting the CDNI Logging File MUST ensure that
the respective insert_HTTP_header_name_here of the
cs(insert_HTTP_header_name_here) listed in the fields directive
Le Faucheur, et al. Standards Track [Page 33]
RFC 7937 CDNI Logging August 2016
comply with HTTP specifications. In particular, this field
name does not include any HTAB, since this would prevent proper
parsing of the fields directive by the entity receiving the
CDNI Logging File.
* Occurrence: There MAY be zero, one, or any number of instances
of this field. For a given insert_HTTP_header_name_here, there
MUST be zero or exactly one instance of this field.
o s-ccid:
* Format: QSTRING
* Field value: This contains the value of the Content Collection
IDentifier (CCID) associated by the uCDN to the content served
by the Surrogate via the CDNI Metadata interface ([CDNI-META]),
prepended by a DQUOTE and appended by a DQUOTE. If the CCID
conveyed in the CDNI Metadata interface contains one or more
DQUOTEs, each DQUOTE MUST be escaped with percent encoding.
For example, if the CCID conveyed in the CDNI Metadata
interface is My_CCIDD"value", then the field value of the
s-ccid is "My_CCID%x22value%X22".
* Occurrence: There MUST be zero or exactly one instance of this
field. For a given insert_HTTP_header_name_here, there MUST be
zero or exactly one instance of this field.
o s-sid:
* Format: QSTRING
* Field value: This contains the value of a Session IDentifier
(SID) generated by the dCDN for a specific HTTP session,
prepended by a DQUOTE and appended by a DQUOTE. In particular,
for an HTTP Adaptive Streaming (HAS) session, the SID value is
included in the Logging Record for every content chunk delivery
of that session in view of facilitating the later correlation
of all the per-content chunk log records of a given HAS
session. See Section 3.4.2.2. of [RFC6983] for more discussion
on the concept of Session IDentifier in the context of HAS. If
the SID conveyed contains one or more DQUOTEs, each DQUOTE MUST
be escaped with percent-encoding. For example, if the SID is
My_SID"value", then the field value of the s-sid is
"My_SID%x22value%x22".
* Occurrence: There MUST be zero or exactly one instance of this
field.
Le Faucheur, et al. Standards Track [Page 34]
RFC 7937 CDNI Logging August 2016
o s-cached:
* Format: 1DIGIT
* Field value: This characterizes whether or not the Surrogate
served the request using content already stored on its local
cache. The allowed values are "0" (for miss) and "1" (for
hit). "1" MUST be used when the Surrogate did serve the request
exclusively using content already stored on its local cache.
"0" MUST be used otherwise (including cases where the Surrogate
served the request using some, but not all, content already
stored on its local cache). Note that a "0" only means a cache
miss in the Surrogate and does not provide any information on
whether or not the content was already stored in another device
of the dCDN, i.e., whether this was a "dCDN hit" or a "dCDN
miss".
* Occurrence: There MUST be zero or exactly one instance of this
field.
CDNI Logging field names are case-insensitive as per the basic ABNF
([RFC5234]). The "fields" directive corresponding to an HTTP Request
Logging Record MUST contain all the fields names whose occurrence is
specified above as "[t]here MUST be one and only one instance of this
field." The corresponding fields value MUST be present in every HTTP
Request Logging Record.
The "fields" directive corresponding to an HTTP Request Logging
Record MAY list all the fields values whose occurrence is specified
above as "[t]here MUST be zero or exactly one instance of this field"
or "[t]here MAY be zero, one, or any number of instances of this
field." The set of such field names actually listed in the "fields"
directive is selected by the CDN generating the CDNI Logging File
based on agreements between the interconnected CDNs established
through mechanisms outside the scope of this specification (e.g.,
contractual agreements). When such a field name is not listed in the
"fields" directive, the corresponding field value MUST NOT be
included in the Logging Record. When such a field name is listed in
the "fields" directive, the corresponding field value MUST be
included in the Logging Record; if the value for the field is not
available, this MUST be conveyed via a dash character ("-").
The fields names listed in the "fields" directive MAY be listed in
the order in which they are listed in Section 3.4.1 or MAY be listed
in any other order.
Le Faucheur, et al. Standards Track [Page 35]
RFC 7937 CDNI Logging August 2016
Logging some specific fields from HTTP requests and responses can
introduce serious security and privacy risks. For example, cookies
will often contain (months) long-lived token values that can be used
to log into a service as the relevant user. Similar values may be
included in other header fields or within URLs or elsewhere in HTTP
requests and responses. Centralizing such values in a CDNI Logging
File can therefore represent a significant increase in risk both for
the user and the web service provider, but also for the CDNs
involved. Therefore, implementations ought to attempt to lower the
probability of such bad outcomes, e.g., by only allowing a configured
set of headers to be added to CDNI Logging Records, or by not
supporting wildcard selection of HTTP request/response fields to add.
Such mechanisms can reduce the probability that security (or privacy)
sensitive values are centralized in CDNI Logging Files. Also, when
agreeing on which HTTP request/response fields are to be provided in
CDNI Logging Files, the uCDN and dCDN administrators ought to
consider these risks. Furthermore, CDNs making use of c-groupid to
identify an aggregate of clients rather than individual clients ought
to realize that, by logging certain header fields, they may create
the possibility to re-identify individual clients. In these cases,
heeding the above advice, or not logging header fields at all, is
particularly important if the goal is to provide logs that do not
identify individual clients.
A dCDN-side implementation of the CDNI Logging interface MUST
implement all the following Logging fields in a CDNI Logging Record
of record-type "cdni_http_request_v1" and MUST support the ability to
include valid values for each of them:
o date
o time
o time-taken
o c-groupid
o s-ip
o s-hostname
o s-port
o cs-method
o cs-uri
o u-uri
Le Faucheur, et al. Standards Track [Page 36]
RFC 7937 CDNI Logging August 2016
o protocol
o sc-status
o sc-total-bytes
o sc-entity-bytes
o cs(insert_HTTP_header_name_here)
o sc(insert_HTTP_header_name_here)
o s-cached
A dCDN-side implementation of the CDNI Logging interface MAY support
the following Logging fields in a CDNI Logging Record of record-type
"cdni_http_request_v1":
o s-ccid
o s-sid
If a dCDN-side implementation of the CDNI Logging interface supports
these fields, it MUST support the ability to include valid values for
them.
An uCDN-side implementation of the CDNI Logging interface MUST be
able to accept CDNI Logging Files with CDNI Logging Records of
record-type "cdni_http_request_v1" containing any CDNI Logging Field
defined in Section 3.4.1 as long as the CDNI Logging Record and the
CDNI Logging File are compliant with the present document.
In case an uCDN-side implementation of the CDNI Logging interface
receives a CDNI Logging File with HTTP Request Logging Records that
do not contain field values for exactly the set of field names
actually listed in the preceding "fields" directive, the
implementation MUST ignore those HTTP Request Logging Records and
MUST accept the other HTTP Request Logging Records.
To ensure that the Logging File is correct, the text MUST be
sanitized before being logged. Null, bare CR, bare LF, and HTAB have
to be removed by escaping them through percent encoding to avoid
confusion with the Logging Record separators.
Le Faucheur, et al. Standards Track [Page 37]
RFC 7937 CDNI Logging August 2016
3.5. CDNI Logging File Extension
The CDNI Logging File contains blocks of directives and blocks of
corresponding records. The supported set of directives is defined
relative to the CDNI Logging File Format version. The complete set
of directives for version "cdni/1.0" are defined in Section 3.3. The
directive list is not expected to require much extension, but when it
does, the new directive MUST be defined and registered in the "CDNI
Logging Directive Names" registry, as described in Figure 9, and a
new version MUST be defined and registered in the "CDNI Logging File
version" registry, as described in Section 6.2. For example, adding
a new CDNI Logging Directive, e.g., "foo", to the set of directives
defined for "cdni/1.0" in Section 3.3, would require registering both
the new CDNI Logging Directive "foo" and a new CDNI Logging File
version, e.g., "CDNI/2.0", which includes all of the existing CDNI
Logging Directives of "cdni/1.0" plus "foo".
It is expected that as new logging requirements arise, the list of
fields to log will change and expand. When adding new fields, the
new fields MUST be defined and registered in the "CDNI Logging Field
Names" registry, as described in Section 6.4, and a new record-type
MUST be defined and registered in the "CDNI Logging record-types"
registry, as described in Section 6.3. For example, adding a new
CDNI Logging Field, e.g., "c-bar", to the set of fields defined for
"cdni_http_request_v1" in Section 3.4.1, would require registering
both the new CDNI Logging Field "c-bar" and a new CDNI record-type,
e.g., "cdni_http_request_v2", which includes all of the existing CDNI
Logging Fields of "cdni_http_request_v1" plus "c-bar".
3.6. CDNI Logging File Examples
Let us consider the upstream CDN and the downstream CDN-labeled uCDN
and dCDN-1 in Figure 1. When dCDN-1 acts as a downstream CDN for
uCDN and performs content delivery on behalf of uCDN, dCDN-1 will
include the CDNI Logging Records corresponding to the content
deliveries performed on behalf of uCDN in the CDNI Logging Files for
uCDN. An example CDNI Logging File communicated by dCDN-1 to uCDN is
shown below in Figure 4.
Le Faucheur, et al. Standards Track [Page 38]
RFC 7937 CDNI Logging August 2016
#version:<HTAB>cdni/1.0<CRLF>
#UUID:<HTAB>urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6<CRLF>
#claimed-origin:<HTAB>cdni-logging-entity.dcdn-1.example.com<CRLF>
#record-type:<HTAB>cdni_http_request_v1<CRLF>
#fields:<HTAB>date<HTAB>time<HTAB>time-taken<HTAB>c-groupid<HTAB>
cs-method<HTAB>u-uri<HTAB>protocol<HTAB>
sc-status<HTAB>sc-total-bytes<HTAB>cs(User-Agent)<HTAB>
cs(Referer)<HTAB>s-cached<CRLF>
2013-05-17<HTAB>00:38:06.825<HTAB>9.058<HTAB>US/TN/MEM/38138<HTAB>
GET<HTAB>
http://cdni-ucdn.dcdn-1.example.com/video/movie100.mp4<HTAB>
HTTP/1.1<HTAB>200<HTAB>6729891<HTAB>"Mozilla/5.0
(Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
"host1.example.com"<HTAB>1<CRLF>
2013-05-17<HTAB>00:39:09.145<HTAB>15.32<HTAB>FR/PACA/NCE/06100<HTAB>
GET<HTAB>
http://cdni-ucdn.dcdn-1.example.com/video/movie118.mp4<HTAB>
HTTP/1.1<HTAB>200<HTAB>15799210<HTAB>"Mozilla/5.0
(Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
"host1.example.com"<HTAB>1<CRLF>
2013-05-17<HTAB>00:42:53.437<HTAB>52.879<HTAB>US/TN/MEM/38138<HTAB>
GET<HTAB>
http://cdni-ucdn.dcdn-1.example.com/video/picture11.mp4<HTAB>
HTTP/1.0<HTAB>200<HTAB>97234724<HTAB>"Mozilla/5.0
(Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
"host5.example.com"<HTAB>0<CRLF>
#SHA256-hash:<HTAB> 64-hexadecimal-digit hash value <CRLF>
Figure 4: CDNI Logging File Example
If uCDN establishes, by some means (e.g., via TLS authentication when
pulling the CDNI Logging File), the identity of the entity from which
it pulled the CDNI Logging File, uCDN can add an established-origin
directive to the CDNI Logging as illustrated below:
#established-origin:<HTAB>cdni-logging-entity.dcdn-1.example.com<CRLF>
Le Faucheur, et al. Standards Track [Page 39]
RFC 7937 CDNI Logging August 2016
As illustrated in Figure 2, uCDN will then ingest the corresponding
CDNI Logging Records into its Collection process, alongside the
Logging Records generated locally by the uCDN itself. This allows
uCDN to aggregate Logging Records for deliveries performed by itself
(through Records generated locally) as well as for deliveries
performed by its downstream CDN(s). This aggregate information can
then be used (after Filtering and Rectification, as illustrated in
Figure 2) by log-consuming applications that take into account
deliveries performed by uCDN as well as by all of its downstream
CDNs.
We observe that the time between
1. when a delivery is completed in dCDN and
2. when the corresponding Logging Record is ingested by the
Collection process in uCDN
depends on a number of parameters such as the Logging Period agreed
to by uCDN and dCDN, how much time uCDN waits before pulling the CDNI
Logging File once it is advertised in the CDNI Logging Feed, and the
time to complete the pull of the CDNI Logging File. Therefore, if we
consider the set of Logging Records aggregated by the Collection
process in uCDN in a given time interval, there could be a permanent
significant timing difference between the CDNI Logging Records
received from the dCDN and the Logging Records generated locally.
For example, in a given time interval, the Collection process in uCDN
may be aggregating Logging Records generated locally by uCDN for
deliveries performed in the last hour and CDNI Logging Records
generated in the dCDN for deliveries in the hour before last.
Say that, for some reason (for example, a Surrogate bug), dCDN-1
could not collect the total number of bytes of the responses sent by
the Surrogate (in other words, the value for sc-total-bytes is not
available). Then the corresponding CDNI Logging Records would
contain a dash character ("-") in lieu of the value for the sc-total-
bytes field (as specified in Section 3.4.1). In that case, the CDNI
Logging File that would be communicated by dCDN-1 to uCDN is shown
below in Figure 5.
Le Faucheur, et al. Standards Track [Page 40]
RFC 7937 CDNI Logging August 2016
#version:<HTAB>cdni/1.0<CRLF>
#UUID:<HTAB>urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6<CRLF>
#claimed-origin:<HTAB>cdni-logging-entity.dcdn-1.example.com<CRLF>
#record-type:<HTAB>cdni_http_request_v1<CRLF>
#fields:<HTAB>date<HTAB>time<HTAB>time-taken<HTAB>c-groupid<HTAB>
cs-method<HTAB>u-uri<HTAB>protocol<HTAB>
sc-status<HTAB>sc-total-bytes<HTAB>cs(User-Agent)<HTAB>
cs(Referer)<HTAB>s-cached<CRLF>
2013-05-17<HTAB>00:38:06.825<HTAB>9.058<HTAB>US/TN/MEM/38138<HTAB>
GET<HTAB>
http://cdni-ucdn.dcdn-1.example.com/video/movie100.mp4<HTAB>
HTTP/1.1<HTAB>200<HTAB>-<HTAB>"Mozilla/5.0
(Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
"host1.example.com"<HTAB>1<CRLF>
2013-05-17<HTAB>00:39:09.145<HTAB>15.32<HTAB>FR/PACA/NCE/06100<HTAB>
GET<HTAB>
http://cdni-ucdn.dcdn-1.example.com/video/movie118.mp4<HTAB>
HTTP/1.1<HTAB>200<HTAB>-<HTAB>"Mozilla/5.0
(Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
"host1.example.com"<HTAB>1<CRLF>
2013-05-17<HTAB>00:42:53.437<HTAB>52.879<HTAB>US/TN/MEM/38138<HTAB>
GET<HTAB>
http://cdni-ucdn.dcdn-1.example.com/video/picture11.mp4<HTAB>
HTTP/1.0<HTAB>200<HTAB>-<HTAB>"Mozilla/5.0
(Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari/533.4"<HTAB>
"host5.example.com"<HTAB>0<CRLF>
#SHA256-hash:<HTAB> 64-hexadecimal-digit hash value <CRLF>
Figure 5: CDNI Logging File Example with a Missing Field Value
Le Faucheur, et al. Standards Track [Page 41]
RFC 7937 CDNI Logging August 2016
3.7. Cascaded CDNI Logging Files Example
Let us consider the cascaded CDN scenario of uCDN, dCDN-2, and dCDN-3
as depicted in Figure 1. After completion of a delivery by dCDN-3 on
behalf of dCDN-2, dCDN-3 will include a corresponding Logging Record
in a CDNI Logging File that will be pulled by dCDN-2 and that is
illustrated below in Figure 6. In practice, a CDNI Logging File is
likely to contain a very high number of CDNI Logging Records.
However, for readability, the example in Figure 6 contains a single
CDNI Logging Record.
#version:<HTAB>cdni/1.0<CRLF>
#UUID:<HTAB>urn:uuid:65718ef-0123-9876-adce4321bcde<CRLF>
#claimed-origin:<HTAB>cdni-logging-entity.dcdn-3.example.com<CRLF>
#record-type:<HTAB>cdni_http_request_v1<CRLF>
#fields:<HTAB>date<HTAB>time<HTAB>time-taken<HTAB>c-groupid<HTAB>
cs-method<HTAB>u-uri<HTAB>protocol<HTAB>
sc-status<HTAB>sc-total-bytes<HTAB>cs(User-Agent)<HTAB>
cs(Referer)<HTAB>s-cached<CRLF>
2013-05-17<HTAB>00:39:09.119<HTAB>14.07<HTAB>US/CA/SFO/94114<HTAB>
GET<HTAB>
http://cdni-dcdn-2.dcdn-3.example.com/video/movie118.mp4<HTAB>
HTTP/1.1<HTAB>200<HTAB>15799210<HTAB>"Mozilla/5.0
(Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari /533.4"<HTAB>
"host1.example.com"<HTAB>1<CRLF>
#SHA256-hash:<HTAB> 64-hexadecimal-digit hash value <CRLF>
Figure 6: Cascaded CDNI Logging File Example (dCDN-3 to dCDN-2)
If dCDN-2 establishes, by some means (e.g., via TLS authentication
when pulling the CDNI Logging File), the identity of the entity from
which it pulled the CDNI Logging File, dCDN-2 can add an established-
origin directive to the CDNI Logging as illustrated below:
#established-origin:<HTAB>cdni-logging-entity.dcdn-3.example.com<CRLF>
dCDN-2 (behaving as an upstream CDN from the viewpoint of dCDN-3)
will then ingest the CDNI Logging Record for the considered dCDN-3
delivery into its Collection process (as illustrated in Figure 2).
This Logging Record may be aggregated with Logging Records generated
locally by dCDN-2 for deliveries performed by dCDN-2 itself. Say,
Le Faucheur, et al. Standards Track [Page 42]
RFC 7937 CDNI Logging August 2016
for illustration, that the content delivery performed by dCDN-3 on
behalf of dCDN-2 had actually been redirected to dCDN-2 by uCDN, and
say that another content delivery has just been redirected by uCDN to
dCDN-2 and that dCDN-2 elected to perform the corresponding delivery
itself. Then, after Filtering and Rectification (as illustrated in
Figure 2), dCDN-2 will include the two Logging Records corresponding
respectively to the delivery performed by dCDN-3 and the delivery
performed by dCDN-2, in the next CDNI Logging File that will be
communicated to uCDN. An example of such a CDNI Logging File is
illustrated below in Figure 7.
#version:<HTAB>cdni/1.0<CRLF>
#UUID:<HTAB>urn:uuid:1234567-8fedc-abab-0987654321ff<CRLF>
#claimed-origin:<HTAB>cdni-logging-entity.dcdn-2.example.com<CRLF>
#record-type:<HTAB>cdni_http_request_v1<CRLF>
#fields:<HTAB>date<HTAB>time<HTAB>time-taken<HTAB>c-groupid<HTAB>
cs-method<HTAB>u-uri<HTAB>protocol<HTAB>
sc-status<HTAB>sc-total-bytes<HTAB>cs(User-Agent)<HTAB>
cs(Referer)<HTAB>s-cached<CRLF>
2013-05-17<HTAB>00:39:09.119<HTAB>14.07<HTAB>US/CA/SFO/94114<HTAB>
GET<HTAB>
http://cdni-ucdn.dcdn-2.example.com/video/movie118.mp4<HTAB>
HTTP/1.1<HTAB>200<HTAB>15799210<HTAB>"Mozilla/5.0
(Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari /533.4"<HTAB>
"host1.example.com"<HTAB>1<CRLF>
2013-05-17<HTAB>01:42:53.437<HTAB>52.879<HTAB>FR/IDF/PAR/75001<HTAB>
GET<HTAB>
http://cdni-ucdn.dcdn-2.example.com/video/picture11.mp4<HTAB>
HTTP/1.0<HTAB>200<HTAB>97234724<HTAB>"Mozilla/5.0
(Windows; U; Windows NT 6.0; en-US) AppleWebKit/533.4 (KHTML, like
Gecko) Chrome/5.0.375.127 Safari /533.4"<HTAB>
"host5.example.com"<HTAB>0<CRLF>
#SHA256-hash:<HTAB> 64-hexadecimal-digit hash value <CRLF>
Figure 7: Cascaded CDNI Logging File Example (dCDN-2 to uCDN)
Le Faucheur, et al. Standards Track [Page 43]
RFC 7937 CDNI Logging August 2016
If uCDN establishes, by some means (e.g., via TLS authentication when
pulling the CDNI Logging File), the identity of the entity from which
it pulled the CDNI Logging File, uCDN can add to the CDNI Logging an
established-origin directive as illustrated below:
#established-origin:<HTAB>cdni-logging-entity.dcdn-2.example.com<CRLF>
In the example of Figure 7, we observe that:
o The first Logging Record corresponds to the Logging Record
communicated earlier to dCDN-2 by dCDN-3, which corresponds to a
delivery redirected by uCDN to dCDN-2 and then redirected by
dCDN-2 to dCDN-3. The fields values in this Logging Record are
copied from the corresponding CDNI Logging Record communicated to
dCDN2 by dCDN-3, with the exception of the u-uri that now reflects
the URI convention between uCDN and dCDN-2 and that presents the
delivery to uCDN as if it was performed by dCDN-2 itself. This
reflects the fact that dCDN-2 had taken full responsibility of the
corresponding delivery (even if in this case, dCDN-2 elected to
redirect the delivery to dCDN-3 so it is actually performed by
dCDN-3 on behalf of dCDN-2).
o The second Logging Record corresponds to a delivery redirected by
uCDN to dCDN-2 and performed by dCDN-2 itself. The time of the
delivery in this Logging Record may be significantly more recent
than the first Logging Record since it was generated locally while
the first Logging Record was generated by dCDN-3 and had to be
advertised, and then pulled and then ingested into the dCDN-2
Collection process, before being aggregated with the second
Logging Record.
4. Protocol for Exchange of CDNI Logging File after Full Collection
This section specifies a protocol for the exchange of CDNI Logging
Files as specified in Section 3 after the CDNI Logging File is fully
collected by the dCDN.
This protocol comprises:
o a CDNI Logging feed, allowing the dCDN to notify the uCDN about
the CDNI Logging Files that can be retrieved by that uCDN from the
dCDN, as well as all the information necessary for retrieving each
of these CDNI Logging Files. The CDNI Logging feed is specified
in Section 4.1.
o a CDNI Logging File pull mechanism, allowing the uCDN to obtain
from the dCDN a given CDNI Logging File at the uCDN's convenience.
The CDNI Logging File pull mechanism is specified in Section 4.2.
Le Faucheur, et al. Standards Track [Page 44]
RFC 7937 CDNI Logging August 2016
An implementation of the CDNI Logging interface on the dCDN side (the
entity generating the CDNI Logging File) MUST support the server side
of the CDNI Logging feed (as specified in Section 4.1) and the server
side of the CDNI Logging pull mechanism (as specified in
Section 4.2).
An implementation of the CDNI Logging interface on the uCDN side (the
entity consuming the CDNI Logging File) MUST support the client side
of the CDNI Logging feed (as specified in Section 4.1) and the client
side of the CDNI Logging pull mechanism (as specified in
Section 4.2).
4.1. CDNI Logging Feed
The server-side implementation of the CDNI Logging feed MUST produce
an Atom feed [RFC4287]. This feed is used to advertise log files
that are available for the client-side to retrieve using the CDNI
Logging pull mechanism.
4.1.1. Atom Formatting
A CDNI Logging feed MUST be structured as an Archived feed, as
defined in [RFC5005], and MUST be formatted in Atom [RFC4287]. This
means it consists of a subscription document that is regularly
updated as new CDNI Logging Files become available, and information
about older CDNI Logging Files is moved into archive documents. Once
created, archive documents are never modified.
Each CDNI Logging File listed in an Atom feed MUST be described in an
atom:entry container element.
The atom:entry MUST contain an atom:content element whose "src"
attribute is a link to the CDNI Logging File and whose "type"
attribute is the MIME Media Type indicating that the entry is a CDNI
Logging File. This MIME Media Type is defined as "application/cdni"
(See [RFC7736]) with the Payload Type (ptype) parameter set to
"logging-file".
For compatibility with some Atom feed readers, the atom:entry MAY
also contain an atom:link entry whose "href" attribute is a link to
the CDNI Logging File and whose "type" attribute is the MIME Media
Type indicating that the entry is a CDNI Logging File using the
"application/cdni" MIME Media Type with the Payload Type (ptype)
parameter set to "logging-file" (see [RFC7736]).
Le Faucheur, et al. Standards Track [Page 45]
RFC 7937 CDNI Logging August 2016
The URI used in the atom:id of the atom:entry MUST contain the UUID
of the CDNI Logging File.
The atom:updated in the atom:entry MUST indicate the time at which
the CDNI Logging File was last updated.
4.1.2. Updates to Log Files and the Feed
CDNI Logging Files MUST NOT be modified by the dCDN once published in
the CDNI Logging feed.
The frequency with which the subscription feed is updated, the period
of time covered by each CDNI Logging File or each archive document,
and timeliness of publishing of CDNI Logging Files are outside the
scope of the present document and are expected to be agreed upon by
uCDN and dCDN via other means (e.g., human agreement).
The server-side implementation MUST be able to set, and SHOULD set,
HTTP-cache control headers on the subscription feed to indicate the
frequency at which the client-side is to poll for updates.
The client-side MAY use HTTP-cache control headers (set by the
server-side) on the subscription feed to determine the frequency at
which to poll for updates. The client-side MAY instead, or in
addition, use other information to determine when to poll for updates
(e.g., a polling frequency that may have been negotiated between the
uCDN and dCDN by mechanisms outside the scope of the present document
and that is to override the indications provided in the HTTP-cache
control headers).
The potential retention limits (e.g., sliding time window) within
which the dCDN is to retain and be ready to serve an archive document
is outside the scope of the present document and is expected to be
agreed upon by uCDN and dCDN via other means (e.g., human agreement).
The server-side implementation MUST retain, and be ready to serve,
any archive document within the agreed retention limits. Outside
these agreed limits, the server-side implementation MAY indicate its
inability to serve (e.g., with HTTP status code 404) an archive
document or MAY refuse to serve it (e.g., with HTTP status code 403
or 410).
Le Faucheur, et al. Standards Track [Page 46]
RFC 7937 CDNI Logging August 2016
4.1.3. Redundant Feeds
The server-side implementation MAY present more than one CDNI Logging
feed for redundancy. Each CDNI Logging File MAY be published in more
than one feed.
A client-side implementation MAY support such redundant CDNI Logging
feeds. If it supports a redundant CDNI Logging feed, the client-side
can use the UUID of the CDNI Logging File, presented in the atom:id
element of the Atom feed, to avoid unnecessarily pulling and storing
a given CDNI Logging File more than once.
4.1.4. Example CDNI Logging Feed
Figure 8 illustrates an example of the subscription document of a
CDNI Logging feed.
Le Faucheur, et al. Standards Track [Page 47]
RFC 7937 CDNI Logging August 2016
<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
<title type="text">CDNI Logging Feed</title>
<updated>2013-03-23T14:46:11Z</updated>
<id>urn:uuid:663ae677-40fb-e99a-049d-c5642916b8ce</id>
<link href="https://dcdn.example/logfeeds/ucdn1"
rel="self" type="application/atom+xml" />
<link href="https://dcdn.example/logfeeds/ucdn1"
rel="current" type="application/atom+xml" />
<link href="https://dcdn.example/logfeeds/ucdn1/201303231400"
rel="prev-archive" type="application/atom+xml" />
<generator version="example version 1">CDNI Log Feed
Generator</generator>
<author><name>dcdn.example</name></author>
<entry>
<title type="text">CDNI Logging File for uCDN at
2013-03-23 14:15:00</title>
<id>urn:uuid:12345678-1234-abcd-00aa-01234567abcd</id>
<updated>2013-03-23T14:15:00Z</updated>
<content src="https://dcdn.example/logs/ucdn/
http-requests-20130323141500000000"
type="application/cdni"
ptype="logging-file"/>
<summary>CDNI Logging File for uCDN at
2013-03-23 14:15:00</summary>
</entry>
<entry>
<title type="text">CDNI Logging File for uCDN at
2013-03-23 14:30:00</title>
<id>urn:uuid:87654321-4321-dcba-aa00-dcba7654321</id>
<updated>2013-03-23T14:30:00Z</updated>
<content src="https://dcdn.example/logs/ucdn/
http-requests-20130323143000000000"
type="application/cdni"
ptype="logging-file"/>
<summary>CDNI Logging File for uCDN at
2013-03-23 14:30:00</summary>
</entry>
...
<entry>
...
</entry>
</feed>
Figure 8: Example Subscription Document of a CDNI Logging Feed
Le Faucheur, et al. Standards Track [Page 48]
RFC 7937 CDNI Logging August 2016
4.2. CDNI Logging File Pull
A client-side implementation of the CDNI Logging interface MAY pull,
at its convenience, a CDNI Logging File that is published by the
server-side in the CDNI Logging Feed (in the subscription document or
an archive document). To do so, the client-side:
o MUST implement HTTP/1.1 ([RFC7230] [RFC7231] [RFC7232] [RFC7233]
[RFC7234] [RFC7235]), MAY also support other HTTP versions (e.g.,
HTTP/2 [RFC7540]), and MAY negotiate which HTTP version is
actually used. This allows operators and implementers to choose
to use later versions of HTTP to take advantage of new features,
while still ensuring interoperability with systems that only
support HTTP/1.1;
o MUST use the URI that was associated to the CDNI Logging File
(within the "src" attribute of the corresponding atom:content
element) in the CDNI Logging Feed;
o MUST support exchange of CDNI Logging Files with no content
encoding applied to the representation;
o MUST support exchange of CDNI Logging Files with "gzip" content
encoding (as defined in [RFC7230]) applied to the representation.
Note that a client-side implementation of the CDNI Logging interface
MAY pull a CDNI Logging File that it has already pulled.
The server-side implementation MUST respond to a valid pull request
by a client-side implementation for a CDNI Logging File published by
the server-side in the CDNI Logging Feed (in the subscription
document or an archive document). The server-side implementation:
o MUST implement HTTP/1.1 to handle the client-side request and MAY
also support other HTTP versions (e.g., HTTP/2);
o MUST include the CDNI Logging File identified by the request URI
inside the body of the HTTP response;
o MUST support exchange of CDNI Logging Files with no content
encoding applied to the representation;
o MUST support exchange of CDNI Logging Files with "gzip" content
encoding (as defined in [RFC7231]) applied to the representation.
Le Faucheur, et al. Standards Track [Page 49]
RFC 7937 CDNI Logging August 2016
Content negotiation approaches defined in [RFC7231] (e.g., using
Accept-Encoding request-header field or Content-Encoding entity-
header field) MAY be used by the client-side and server-side
implementations to establish the content coding to be used for a
particular exchange of a CDNI Logging File.
Applying compression content encoding (such as "gzip") is expected to
mitigate the impact of exchanging the large volumes of logging
information expected across CDNs. This is expected to be
particularly useful in the presence of HTTP Adaptive Streaming (HAS)
that, as per the present version of the document, will result in a
separate CDNI Log Record for each HAS segment delivery in the CDNI
Logging File.
The potential retention limits (e.g., sliding time window and maximum
aggregate file storage quotas) within which the dCDN is to retain and
be ready to serve a CDNI Logging File previously advertised in the
CDNI Logging Feed is outside the scope of the present document and is
expected to be agreed upon by uCDN and dCDN via other means (e.g.,
human agreement). The server-side implementation MUST retain, and be
ready to serve, any CDNI Logging File within the agreed retention
limits. Outside these agreed limits, the server-side implementation
MAY indicate its inability to serve (e.g., with HTTP status code 404)
a CDNI Logging File or MAY refuse to serve it (e.g., with HTTP status
code 403 or 410).
5. Protocol for Exchange of CDNI Logging File During Collection
We note that, in addition to the CDNI Logging File exchange protocol
specified in Section 4, implementations of the CDNI Logging interface
may also support other mechanisms to exchange CDNI Logging Files. In
particular, such mechanisms might allow the exchange of the CDNI
Logging File to start before the file is fully collected. This can
allow CDNI Logging Records to be communicated by the dCDN to the uCDN
as they are gathered by the dCDN without having to wait until all the
CDNI Logging Records of the same logging period are collected in the
corresponding CDNI Logging File. This approach is commonly referred
to as the "tailing" of the file.
Such an approach could be used, for example, to exchange logging
information with a significantly reduced time-lag (e.g., sub-minute
or sub-second) between when the event occurred in the dCDN and when
the corresponding CDNI Logging Record is made available to the uCDN.
This can satisfy log-consuming applications requiring extremely fresh
logging information such as near-real-time content delivery
monitoring. Such mechanisms are for further study and are outside
the scope of this document.
Le Faucheur, et al. Standards Track [Page 50]
RFC 7937 CDNI Logging August 2016
6. IANA Considerations
6.1. CDNI Logging Directive Names Registry
IANA has created a new "CDNI Logging Directive Names" subregistry
under the "Content Delivery Networks Interconnection (CDNI)
Parameters" registry.
The initial contents of the "CDNI Logging Directives" registry
comprise the names of the directives specified in Section 3.3 of the
present document and are as follows:
+------------------------------+-----------+
| Directive Name | Reference |
+------------------------------+-----------+
| version | RFC 7937 |
| UUID | RFC 7937 |
| claimed-origin | RFC 7937 |
| established-origin | RFC 7937 |
| remark | RFC 7937 |
| record-type | RFC 7937 |
| fields | RFC 7937 |
| SHA256-hash | RFC 7937 |
+------------------------------+-----------+
Figure 9: CDNI Logging Directive Names Registry
Within the registry, names are to be allocated by IANA according to
the "Specification Required" policy specified in [RFC5226].
Directive names are to be allocated by IANA with a format of
NAMEFORMAT (see Section 3.1). All directive names defined in the
Logging File are case-insensitive as per the basic ABNF ([RFC5234]).
Each specification that defines a new CDNI Logging directive needs to
contain a description for the new directive with the same set of
information as provided in Section 3.3 (i.e., format, directive
value, and occurrence).
6.2. CDNI Logging File version Registry
IANA has created a new "CDNI Logging File version" subregistry under
the "Content Delivery Networks Interconnection (CDNI) Parameters"
registry.
Le Faucheur, et al. Standards Track [Page 51]
RFC 7937 CDNI Logging August 2016
The initial contents of the "CDNI Logging File version" registry
comprise the value "cdni/1.0" specified in Section 3.3 of the present
document and are as follows:
+-----------------+-----------+----------------------------------+
| version | Reference | Description |
+-----------------+-----------+----------------------------------+
| cdni/1.0 | RFC 7937 | CDNI Logging File version 1.0 |
| | | as specified in RFC 7937 |
+-----------------+-----------+----------------------------------+
Figure 10: CDNI Logging File version Registry
Within the registry, version values are to be allocated by IANA
according to the "Specification Required" policy specified in
[RFC5226]. Version values are to be allocated by IANA with a format
of NAMEFORMAT (see Section 3.1). All version values defined in the
Logging File are case-insensitive as per the basic ABNF ([RFC5234]).
6.3. CDNI Logging record-types Registry
IANA has created a new "CDNI Logging record-types" subregistry under
the "Content Delivery Networks Interconnection (CDNI) Parameters"
registry.
The initial contents of the "CDNI Logging record-types" registry
comprise the names of the CDNI Logging record-types specified in
Section 3.4 of the present document and are as follows:
+----------------------+-----------+---------------------------------+
| record-types | Reference | Description |
+----------------------+-----------+---------------------------------+
| cdni_http_request_v1 | RFC 7937 | CDNI Logging Record version 1 |
| | | for content delivery using HTTP |
+----------------------+-----------+---------------------------------+
Figure 11: CDNI Logging record-types Registry
Within the registry, record-types are to be allocated by IANA
according to the "Specification Required" policy specified in
[RFC5226]. Record-types are to be allocated by IANA with a format of
NAMEFORMAT (see Section 3.1). All record-types defined in the
Logging File are case-insensitive as per the basic ABNF ([RFC5234]).
Le Faucheur, et al. Standards Track [Page 52]
RFC 7937 CDNI Logging August 2016
Each specification that defines a new record-type needs to contain a
description for the new record-type with the same set of information
as provided in Section 3.4.1. This includes:
o A list of all the CDNI Logging fields that can appear in a CDNI
Logging Record of the new record-type
o For all these fields: a specification of the occurrence for each
Field in the new record-type
o For every newly defined Field, i.e., for every Field that results
in a registration in the "CDNI Logging Field Names" registry
(Section 6.4): a specification of the field name, format, and
field value.
6.4. CDNI Logging Field Names Registry
IANA has created a new "CDNI Logging Field Names" subregistry under
the "Content Delivery Networks Interconnection (CDNI) Parameters"
registry.
This registry is intended to be shared across the currently defined
record-type (i.e., cdni_http_request_v1) as well as potentially other
CDNI Logging record-types that may be defined in separate
specifications. When a field from this registry is used by another
CDNI Logging record-type, it is to be used with the exact semantics
and format specified in the document that registered this field and
that is identified in the Reference column of the registry. If
another CDNI Logging record-type requires a field with semantics that
are not strictly identical, or a format that is not strictly
identical, then this new field is to be registered in the registry
with a different field name. When a field from this registry is used
by another CDNI Logging record-type, it can be used with different
occurrence rules.
Le Faucheur, et al. Standards Track [Page 53]
RFC 7937 CDNI Logging August 2016
The initial contents of the "CDNI Logging Fields Names" registry
comprise the names of the CDNI Logging fields specified in
Section 3.4 of the present document and are as follows:
+------------------------------------------+-----------+
| Field Name | Reference |
+------------------------------------------+-----------+
| date | RFC 7937 |
| time | RFC 7937 |
| time-taken | RFC 7937 |
| c-groupid | RFC 7937 |
| s-ip | RFC 7937 |
| s-hostname | RFC 7937 |
| s-port | RFC 7937 |
| cs-method | RFC 7937 |
| cs-uri | RFC 7937 |
| u-uri | RFC 7937 |
| protocol | RFC 7937 |
| sc-status | RFC 7937 |
| sc-total-bytes | RFC 7937 |
| sc-entity-bytes | RFC 7937 |
| cs(insert_HTTP_header_name_here) | RFC 7937 |
| sc(insert_HTTP_header_name_here) | RFC 7937 |
| s-ccid | RFC 7937 |
| s-sid | RFC 7937 |
| s-cached | RFC 7937 |
+------------------------------------------+-----------+
Figure 12: CDNI Logging Field Names Registry
Within the registry, names are to be allocated by IANA according to
the "Specification Required" policy specified in [RFC5226]. Field
names are to be allocated by IANA with a format of NHTABSTRING (see
Section 3.1). All field names defined in the Logging File are case-
insensitive as per the basic ABNF ([RFC5234]).
Le Faucheur, et al. Standards Track [Page 54]
RFC 7937 CDNI Logging August 2016
6.5. CDNI Logging Payload Type
IANA has registered the following new Payload Type in the "CDNI
Payload Types" registry for use with the application/cdni MIME media
type.
+----------------------+---------------+
| Payload Type | Specification |
+----------------------+---------------+
| logging-file | RFC 7937] |
+----------------------+---------------+
Figure 13: CDNI Logging Payload Type
The purpose of the logging-file payload type is to distinguish
between CDNI Logging Files and other CDNI messages.
o Interface: LI
o Encoding: See Section 3.2, Section 3.3, and Section 3.4
7. Security Considerations
7.1. Authentication, Authorization, Confidentiality, and Integrity
Protection
An implementation of the CDNI Logging interface MUST support TLS
transport of the CDNI Logging feed (Section 4.1) and of the CDNI
Logging File pull (Section 4.2) as per [RFC2818] and [RFC7230].
TLS MUST be used by the server-side and the client-side of the CDNI
Logging feed, as well as the server-side and the client-side of the
CDNI Logging File pull mechanism, including authentication of the
remote end, unless alternate methods are used for ensuring the
security of the information exchanged over the LI interface (such as
setting up an IPsec tunnel between the two CDNs or using a physically
secured internal network between two CDNs that are owned by the same
corporate entity).
The use of TLS for transport of the CDNI Logging feed and CDNI
Logging File pull allows:
o the dCDN and uCDN to authenticate each other using TLS client auth
and TLS server auth.
Le Faucheur, et al. Standards Track [Page 55]
RFC 7937 CDNI Logging August 2016
And, once they have mutually authenticated each other, it allows:
o the dCDN and uCDN to authorize each other (to ensure they are
transmitting/receiving CDNI Logging File to/from an authorized
CDN).
o the CDNI Logging information to be transmitted with
confidentiality.
o the integrity of the CDNI Logging information to be protected
during the exchange.
When TLS is used, the general TLS usage guidance in [RFC7525] MUST be
followed.
The SHA256-hash directive inside the CDNI Logging File provides
additional integrity protection, this time targeting potential
corruption of the CDNI Logging information during the CDNI Logging
File generation, storage, or exchange. This mechanism does not
itself allow restoration of the corrupted CDNI Logging information,
but it allows detection of such corruption, and therefore triggering
of appropriate corrective actions (e.g., discard of corrupted
information, and attempt to re-obtain the CDNI Logging information).
Note that the SHA256-hash does not protect against tampering by a
third party, since such a third party could have recomputed and
updated the SHA256-hash after tampering. Protection against third-
party tampering, when the CDNI Logging File is communicated over the
CDN Logging interface, can be achieved as discussed above through the
use of TLS.
7.2. Denial of Service
This document does not define a specific mechanism to protect against
Denial-of-Service (DoS) attacks on the Logging interface. However,
the CDNI Logging feed and CDNI Logging pull endpoints are typically
to be accessed only by a very small number of valid remote endpoints,
and therefore can be easily protected against DoS attacks through the
usual conventional DoS-protection mechanisms such as firewalling or
use of Virtual Private Networks (VPNs).
Protection of dCDN Surrogates against spoofed delivery requests is
outside the scope of the CDNI Logging interface.
Le Faucheur, et al. Standards Track [Page 56]
RFC 7937 CDNI Logging August 2016
7.3. Privacy
CDNs have the opportunity to collect detailed information about the
downloads performed by end users. A dCDN is expected to collect such
information into CDNI Logging Files, which are then communicated to a
uCDN.
Having detailed CDNI Logging information known by the dCDN in itself
does not represent a particular privacy concern since the dCDN is
obviously fully aware of all information logged since it generated
the information in the first place.
Transporting detailed CDNI Logging information over the HTTP-based
CDNI Logging interface does not represent a particular privacy
concern because it is protected by the usual privacy-protection
mechanism (e.g., TLS).
When HTTP redirection is used between the uCDN and the dCDN, making
detailed CDNI Logging information known to the uCDN does not
represent a particular privacy concern because the uCDN is already
exposed at request redirection time to most of the information that
shows up as CDNI Logging information (e.g., end-user IP address, URL,
and HTTP headers). When DNS redirection is used between the uCDN and
the dCDN, there are cases where there is no privacy concern in making
detailed CDNI logging information known to the uCDN; this may be the
case, for example, where (1) it is considered that because the uCDN
has the authority (with respect to the CSP) and control on how the
requests are delivered (including whether it is served by the uCDN
itself or by a dCDN), the uCDN is entitled to access all detailed
information related to the corresponding deliveries, and (2) there is
no legal reason to restrict access by the uCDN to all this detailed
information. Conversely still, when DNS redirection is used between
the uCDN and the dCDN, there are cases where there may be some
privacy concern in making detailed CDNI Logging information known to
the uCDN; this may be the case, for example, because the uCDN is in a
different jurisdiction to the dCDN, resulting is some legal reasons
to restrict access by the uCDN to all the detailed information
related to the deliveries. In this latter case, the privacy concerns
can be taken into account when the uCDN and dCDN agree about which
fields are to be conveyed inside the CDNI Logging Files and which
privacy protection mechanism is to be used as discussed in the
definition of the c-groupid field specified in Section 3.4.1.
Another privacy concern arises from the fact that large volumes of
detailed information about content delivery to users, potentially
traceable back to individual users, may be collected in CDNI Logging
Files. These CDNI Logging Files represent high-value targets, likely
concentrated in a fairly centralized system (although the CDNI
Le Faucheur, et al. Standards Track [Page 57]
RFC 7937 CDNI Logging August 2016
Logging architecture does not mandate a particular level of
centralization/distribution) and at risk of potential data
exfiltration. Note that the means of such data exfiltration are
beyond the scope of the CDNI Logging interface itself (e.g.,
corrupted employee, corrupted logging storage system, etc.). This
privacy concern calls for some protection.
The collection of large volumes of such information into CDNI Logging
Files introduces potential end-users' privacy protection concerns.
Mechanisms to address these concerns are discussed in the definition
of the c-groupid field specified in Section 3.4.1.
The use of mutually authenticated TLS to establish a secure session
for the transport of the CDNI Logging feed and CDNI Logging pull as
discussed in Section 7.1 provides confidentiality while the Logging
information is in transit and prevents any party other than the
authorized uCDN to gain access to the logging information.
We also note that the query string portion of the URL that may be
conveyed inside the cs-uri and u-uri fields of CDNI Logging Files, or
the HTTP cookies( [RFC6265]) that may be conveyed as part of the
cs(<HTTP-header-name>) field of CDNI Logging Files, may contain
personal information or information that can be exploited to derive
personal information. Where this is a concern, the CDNI Logging
interface specification allows the dCDN to not include the cs-uri and
to include a u-uri that removes (or hides) the sensitive part of the
query string and allows the dCDN to not include the cs(<HTTP-header-
name>) fields corresponding to HTTP headers associated with cookies.
8. References
8.1. Normative References
[AES] NIST, "Advanced Encryption Standard (AES)", National
Institute of Standards and Technology FIPS 197, November
2001, <http://csrc.nist.gov/publications/fips/fips197/
fips-197.pdf>.
[GCM] NIST, "Recommendation for Block Cipher Modes of Operation:
Galois/Counter Mode (GCM) and GMAC", National Institute of
Standards and Technology SP 800-38D,
DOI 10.6028/NIST.SP.800-38D, November 2007,
<http://csrc.nist.gov/publications/nistpubs/800-38D/
SP-800-38D.pdf>.
Le Faucheur, et al. Standards Track [Page 58]
RFC 7937 CDNI Logging August 2016
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<http://www.rfc-editor.org/info/rfc3339>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<http://www.rfc-editor.org/info/rfc4122>.
[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
Syndication Format", RFC 4287, DOI 10.17487/RFC4287,
December 2005, <http://www.rfc-editor.org/info/rfc4287>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<http://www.rfc-editor.org/info/rfc4648>.
[RFC5005] Nottingham, M., "Feed Paging and Archiving", RFC 5005,
DOI 10.17487/RFC5005, September 2007,
<http://www.rfc-editor.org/info/rfc5005>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
Le Faucheur, et al. Standards Track [Page 59]
RFC 7937 CDNI Logging August 2016
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<http://www.rfc-editor.org/info/rfc7231>.
[RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
DOI 10.17487/RFC7232, June 2014,
<http://www.rfc-editor.org/info/rfc7232>.
[RFC7233] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed.,
"Hypertext Transfer Protocol (HTTP/1.1): Range Requests",
RFC 7233, DOI 10.17487/RFC7233, June 2014,
<http://www.rfc-editor.org/info/rfc7233>.
[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
RFC 7234, DOI 10.17487/RFC7234, June 2014,
<http://www.rfc-editor.org/info/rfc7234>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<http://www.rfc-editor.org/info/rfc7235>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <http://www.rfc-editor.org/info/rfc7525>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>.
[SHA-3] NIST, "SHA-3 Standard: Permutation-Based Hash and
Extendable-Output Functions", National Institute of
Standards and Technology FIPS 202,
DOI 10.6028/NIST.FIPS.202, August 2015,
<http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf>.
Le Faucheur, et al. Standards Track [Page 60]
RFC 7937 CDNI Logging August 2016
8.2. Informative References
[ATOMPUB] Snell, J., "Atom Link Extensions", Work in Progress,
draft-snell-atompub-link-extensions-09, June 2012.
[CDNI-META]
Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,
"CDN Interconnection Metadata", Work in Progress,
draft-ietf-cdni-metadata-20, August 2016.
[CHAR_SET] IANA, "Character Sets",
<http://www.iana.org/assignments/character-sets>.
[ELF] Phillip M. Hallam-Baker, and Brian Behlendorf, "Extended
Log File Format", W3C Working Draft, WD-logfile-960323,
<http://www.w3.org/TR/WD-logfile.html>.
[RFC1945] Berners-Lee, T., Fielding, R., and H. Frystyk, "Hypertext
Transfer Protocol -- HTTP/1.0", RFC 1945,
DOI 10.17487/RFC1945, May 1996,
<http://www.rfc-editor.org/info/rfc1945>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000,
<http://www.rfc-editor.org/info/rfc2818>.
[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
Key Derivation Function (HKDF)", RFC 5869,
DOI 10.17487/RFC5869, May 2010,
<http://www.rfc-editor.org/info/rfc5869>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<http://www.rfc-editor.org/info/rfc6234>.
[RFC6265] Barth, A., "HTTP State Management Mechanism", RFC 6265,
DOI 10.17487/RFC6265, April 2011,
<http://www.rfc-editor.org/info/rfc6265>.
[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, DOI 10.17487/RFC6707, September
2012, <http://www.rfc-editor.org/info/rfc6707>.
Le Faucheur, et al. Standards Track [Page 61]
RFC 7937 CDNI Logging August 2016
[RFC6770] Bertrand, G., Ed., Stephan, E., Burbridge, T., Eardley,
P., Ma, K., and G. Watson, "Use Cases for Content Delivery
Network Interconnection", RFC 6770, DOI 10.17487/RFC6770,
November 2012, <http://www.rfc-editor.org/info/rfc6770>.
[RFC6983] van Brandenburg, R., van Deventer, O., Le Faucheur, F.,
and K. Leung, "Models for HTTP-Adaptive-Streaming-Aware
Content Distribution Network Interconnection (CDNI)",
RFC 6983, DOI 10.17487/RFC6983, July 2013,
<http://www.rfc-editor.org/info/rfc6983>.
[RFC7336] Peterson, L., Davie, B., and R. van Brandenburg, Ed.,
"Framework for Content Distribution Network
Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336,
August 2014, <http://www.rfc-editor.org/info/rfc7336>.
[RFC7337] Leung, K., Ed. and Y. Lee, Ed., "Content Distribution
Network Interconnection (CDNI) Requirements", RFC 7337,
DOI 10.17487/RFC7337, August 2014,
<http://www.rfc-editor.org/info/rfc7337>.
[RFC7736] Ma, K., "Content Delivery Network Interconnection (CDNI)
Media Type Registration", RFC 7736, DOI 10.17487/RFC7736,
December 2015, <http://www.rfc-editor.org/info/rfc7736>.
[TLS-1.3] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", Work in Progress, draft-ietf-tls-tls13-15,
August 2016.
Le Faucheur, et al. Standards Track [Page 62]
RFC 7937 CDNI Logging August 2016
Acknowledgments
This document borrows from the W3C Extended Log Format [ELF].
Rob Murray significantly contributed into the text of Section 4.1.
The authors thank Ben Niven-Jenkins, Kevin Ma, David Mandelberg, and
Ray van Brandenburg for their ongoing input.
Brian Trammel and Rich Salz made significant contributions into
making this interface privacy-friendly.
Finally, we also thank Sebastien Cubaud, Pawel Grochocki, Christian
Jacquenet, Yannick Le Louedec, Anne Marrec, Emile Stephan, Fabio
Costa, Sara Oueslati, Yvan Massot, Renaud Edel, Joel Favier, and the
contributors of the EU FP7 OCEAN project for their input in the early
draft versions of this document.
Authors' Addresses
Francois Le Faucheur (editor)
France
Phone: +33 6 19 98 50 90
Email: flefauch@gmail.com
Gilles Bertrand (editor)
Phone: +41 76 675 91 44
Email: gilbertrand@gmail.com
Iuniana Oprescu (editor)
France
Email: iuniana.oprescu@gmail.com
Roy Peterkofsky
Google Inc.
345 Spear St, 4th Floor
San Francisco CA 94105
United States of America
Email: peterkofsky@google.com
Le Faucheur, et al. Standards Track [Page 63]