Internet Engineering Task Force G. Bertrand, Ed.
Internet-Draft I. Oprescu, Ed.
Intended status: Informational E. Stephan
Expires: August 26, 2013 France Telecom - Orange
R. Peterkofsky
Skytide, Inc.
F. Le Faucheur, Ed.
Cisco Systems
P. Grochocki
Orange Polska
February 22, 2013
CDNI Logging Interface
draft-ietf-cdni-logging-01
Abstract
This memo specifies the Logging interface between a downstream CDN
(dCDN) and an upstream CDN (uCDN) that are interconnected as per the
CDN Interconnection (CDNI) framework. First, it describes a
reference model for CDNI logging. Then, it specifies the actual
protocol for CDNI logging information exchange covering the
information elements as well as the transport of those elements.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 26, 2013.
Copyright Notice
Copyright (c) 2013 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
Bertrand, et al. Expires August 26, 2013 [Page 1]
Internet-Draft CDNI Logging February 2013
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.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Bertrand, et al. Expires August 26, 2013 [Page 2]
Internet-Draft CDNI Logging February 2013
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 8
2. CDNI Logging Reference Model . . . . . . . . . . . . . . . . . 8
2.1. CDNI Logging interactions . . . . . . . . . . . . . . . . 8
2.2. Overall Logging Chain . . . . . . . . . . . . . . . . . . 12
2.2.1. Logging Generation and During-Generation
Aggregation . . . . . . . . . . . . . . . . . . . . . 13
2.2.2. Logging Collection . . . . . . . . . . . . . . . . . . 14
2.2.3. Logging Filtering . . . . . . . . . . . . . . . . . . 14
2.2.4. Logging Rectification and Post-Generation
Aggregation . . . . . . . . . . . . . . . . . . . . . 15
2.2.5. Log-Consuming Applications . . . . . . . . . . . . . . 15
2.2.5.1. Maintenance/Debugging . . . . . . . . . . . . . . 15
2.2.5.2. Accounting . . . . . . . . . . . . . . . . . . . . 16
2.2.5.3. Analytics and Reporting . . . . . . . . . . . . . 16
2.2.5.4. Security . . . . . . . . . . . . . . . . . . . . . 16
2.2.5.5. Legal Logging Duties . . . . . . . . . . . . . . . 16
2.2.5.6. Notions common to multiple Log Consuming
Applications . . . . . . . . . . . . . . . . . . . 16
3. CDNI Logging Transport Requirements . . . . . . . . . . . . . 18
3.1. Timeliness . . . . . . . . . . . . . . . . . . . . . . . . 19
3.2. Reliability . . . . . . . . . . . . . . . . . . . . . . . 19
3.3. Security . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4. Scalability . . . . . . . . . . . . . . . . . . . . . . . 19
3.5. Consistency between CDNI Logging and CDN Logging . . . . . 20
3.6. Dispatching/Filtering . . . . . . . . . . . . . . . . . . 20
4. CDNI Logging Information Structure and Transport . . . . . . . 20
5. CDNI Logging Fields . . . . . . . . . . . . . . . . . . . . . 22
5.1. Semantics of CDNI Logging Fields . . . . . . . . . . . . . 22
5.2. Syntax of CDNI Logging Fields . . . . . . . . . . . . . . 26
6. CDNI Logging Records . . . . . . . . . . . . . . . . . . . . . 27
6.1. Content Delivery . . . . . . . . . . . . . . . . . . . . . 27
6.2. Content Invalidation and Purging . . . . . . . . . . . . . 29
6.3. Request Routing . . . . . . . . . . . . . . . . . . . . . 29
6.4. Logging Extensibility . . . . . . . . . . . . . . . . . . 29
7. CDNI Logging File Format . . . . . . . . . . . . . . . . . . . 29
7.1. Logging Files . . . . . . . . . . . . . . . . . . . . . . 29
7.2. File Format . . . . . . . . . . . . . . . . . . . . . . . 29
7.2.1. Headers . . . . . . . . . . . . . . . . . . . . . . . 30
7.2.2. Body (Logging Records) Format . . . . . . . . . . . . 31
7.2.3. Footer Format . . . . . . . . . . . . . . . . . . . . 31
8. CDNI Logging File Transport Protocol . . . . . . . . . . . . . 31
9. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 32
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32
11. Security Considerations . . . . . . . . . . . . . . . . . . . 32
Bertrand, et al. Expires August 26, 2013 [Page 3]
Internet-Draft CDNI Logging February 2013
11.1. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 33
11.2. Non Repudiation . . . . . . . . . . . . . . . . . . . . . 33
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 33
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 33
13.1. Normative References . . . . . . . . . . . . . . . . . . . 33
13.2. Informative References . . . . . . . . . . . . . . . . . . 33
Appendix A. Examples Log Format . . . . . . . . . . . . . . . . . 34
A.1. W3C Common Log File (CLF) Format . . . . . . . . . . . . . 35
A.2. W3C Extended Log File (ELF) Format . . . . . . . . . . . . 35
A.3. National Center for Supercomputing Applications (NCSA)
Common Log Format . . . . . . . . . . . . . . . . . . . . 37
A.4. NCSA Combined Log Format . . . . . . . . . . . . . . . . . 37
A.5. NCSA Separate Log Format . . . . . . . . . . . . . . . . . 37
A.6. Squid 2.0 Native Log Format for Access Logs . . . . . . . 37
Appendix B. Requirements . . . . . . . . . . . . . . . . . . . . 38
B.1. Additional Requirements . . . . . . . . . . . . . . . . . 38
B.2. Compliancy with Requirements draft . . . . . . . . . . . . 39
Appendix C. Analysis of candidate protocols for Logging
Transport . . . . . . . . . . . . . . . . . . . . . . 39
C.1. Syslog . . . . . . . . . . . . . . . . . . . . . . . . . . 40
C.2. XMPP . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
C.3. SNMP . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 40
Bertrand, et al. Expires August 26, 2013 [Page 4]
Internet-Draft CDNI Logging February 2013
1. Introduction
This memo specifies the Logging interface between a downstream CDN
(dCDN) and an upstream CDN (uCDN). First, it describes a reference
model for CDNI logging. Then, it specifies the actual protocol for
CDNI logging information exchange covering the information elements
as well as the transport of those elements.
The reader should be familiar with the work of the CDNI WG:
o CDNI problem statement [RFC6707] and framework
[I-D.ietf-cdni-framework] identify a Logging interface,
o Section 7 of [I-D.ietf-cdni-requirements] specifies a set of
requirements for Logging,
o [RFC6770] outlines real world use-cases for interconnecting CDNs.
These use cases require the exchange of Logging information
between the dCDN and the uCDN.
As stated in [RFC6707], "the CDNI Logging interface enables details
of logs or events to be exchanged between interconnected CDNs".
The present document describes:
o The CDNI Logging reference model (Section 2),
o The CDNI Logging information structure and Transport (Section 4),
o The CDNI Logging Fields (Section 5),
o The CDNI Logging Records (Section 6),
o The CDNI Logging File format (Section 7),
o The CDNI Logging File Transport Protocol (Section 8),
In the Appendices, the document provides:
o A list of identified requirements (Appendix B.1), which should be
considered for inclusion in [I-D.ietf-cdni-requirements],
1.1. Terminology
In this document, the first letter of each CDNI-specific term is
capitalized. We adopt the terminology described in [RFC6707] and
[I-D.ietf-cdni-framework], and extend it with the additional terms
defined below.
Bertrand, et al. Expires August 26, 2013 [Page 5]
Internet-Draft CDNI Logging February 2013
For clarity, we use the word "Log" only for referring to internal CDN
logs and we use the word "Logging" for any inter-CDN information
exchange and processing operations related to CDNI Logging interface.
Log and Logging formats may be different.
CDN Logging information: logging information generated and collected
within a CDN
CDNI Logging information: logging information exchanged across CDNs
using the CDNI Logging Interface
Logging information: logging information generated and collected
within a CDN or obtained from another CDN using the CDNI Logging
Interface
CDNI Logging Field: an atomic element of information that can be
included in a CDNI Logging Record. The time an event/task started,
the IP address of an End user to whom content was delivered, and the
URI of the content delivered are examples of CDNI Logging Fields.
CDNI Logging Record: an information record providing information
about a specific event. This comprises a collection of CDNI Logging
Fields.
Separator Character: a specific character used to enable the parsing
of Logging Records. This character separates the Logging Fields that
compose a Logging Record.
CDNI Logging File: a file containing CDNI Logging Records, as well as
additional information facilitating the processing of the CDNI
Logging Records.
CDN Reporting: the process of providing the relevant information that
will be used to create a formatted content delivery report provided
to the CSP in deferred time. Such information typically includes
aggregated data that can cover a large period of time (e.g., from
hours to several months). Uses of Reporting include the collection
of charging data related to CDN services and the computation of Key
Performance Indicators (KPIs).
CDN Monitoring: the process of providing content delivery information
in real-time. Monitoring typically includes data in real time to
provide visibility of the deliveries in progress, for service
operation purposes. It presents a view of the global health of the
services as well as information on usage and performance, for network
services supervision and operation management. In particular,
monitoring data can be used to generate alarms.
Bertrand, et al. Expires August 26, 2013 [Page 6]
Internet-Draft CDNI Logging February 2013
End-User experience management: study of Logging data using
statistical analysis to discover, understand, and predict user
behavior patterns.
Class-of-requests: A Class-of-requests identifies a set of content
Requests, related to a specific CSP, received from clients in a given
footprint and sharing common properties. These properties include:
o Any header, URL parameter, query parameter of an HTTP (or RTMP)
content request
o Any header, or sub-domain of the FQDN of a DNS lookup request
Examples:
o Class-of-Requests = all the requests that include the HTTP header
"User-Agent: Mozilla/5.0" related to CSP
"http://*.cdn.example.com" from AS3215
o Class-of-Requests = all the DNS requests from anywhere and related
to CSP "cdn*.example.com"
Delivery Service: A Delivery Service is defined by a set of Class-of-
Requests and a list of parameters that apply to all these Class-of-
Requests (logging format, delivery quality/capabilities
requirements...)
Service Agreement: A service agreement is defined by a uCDN
identifier, a dCDN identifier, a set of Delivery Services and a list
of parameters that apply to the Service Agreement.
Once a Service Agreement is agreed between the administrative
entities managing the CDNs to be interconnected, the upstream CDN and
the downstream CDN of the CDNI interconnection must be configured
according to this agreed Service Agreement. For instance, a given
uCDN (uCDN1) may request a given dCDN (dCDN1) to configure one
Delivery Service for handling requests for HTTP Adaptive streaming
videos delegated by uCDN1 and related to a specific CSP (CSP1) and
another one for handling requests for static pictures delegated by
uCDN1 and related to CSP1. These Delivery services would belong to
the Service Agreement between uCDN1 and dCDN1 for CSP1. In this
simple example, uCDN1 may request dCDN1 to include Delivery Service
information in its CDNI Logging, to help uCDN1 to provide relevant
reports to CSP1.
Bertrand, et al. Expires August 26, 2013 [Page 7]
Internet-Draft CDNI Logging February 2013
1.2. Abbreviations
o API: Application Programming Interface
o CCID: Content Collection Identifier
o CDN: Content Delivery Network
o CDNP: Content Delivery Network Provider
o CoDR: Content Delivery Record
o CSP: Content Service Provider
o DASH: Dynamic Adaptive Streaming over HTTP
o dCDN: downstream CDN
o FTP: File Transfer Protocol
o HAS: HTTP Adaptive Streaming
o KPI: Key Performance Indicator
o PVR: Personal Video Recorder
o SID: Session Identifier
o SFTP: SSH File Transfer Protocol
o SNMP: Simple Network Management Protocol
o uCDN: upstream CDN
2. CDNI Logging Reference Model
2.1. CDNI Logging interactions
The CDNI logging reference model between a given uCDN and a given
dCDN involves the following interactions:
o customization by the uCDN of the CDNI logging information to be
provided by the dCDN to the uCDN (e.g. control of which logging
fields are to be communicated to the uCDN for a given task
performed by the dCDN, control of which types of events are to be
logged). The dCDN takes into account this CDNI logging
customization information to determine what logging information to
Bertrand, et al. Expires August 26, 2013 [Page 8]
Internet-Draft CDNI Logging February 2013
provide to the uCDN, but it may, or may not, take into account
this CDNI logging customization information to influence what CDN
logging information is to be generated and collected within the
dCDN (e.g. even if the uCDN requests a restricted subset of the
logging information, the dCDN may elect to generate a broader set
of logging information). The mechanism to support the
customisation by the uCDN of CDNI Logging information is outside
the scope of this document and left for further study. We note
that the CDNI Control interface ore the CDNI Metadata interfaces
appear as candidate interfaces on which to potentially build such
a customisation mechanism. Before such a mechanism is available,
the uCDN and dCDN are expected to agree off-line on what CDNI
logging information is to be provide by dCDN to UCDN and rely on
management plane actions to configure the CDNI Logging functions
to generate (respectively, expect) in dCDN (respectively, in
uCDN).
o generation and collection by the dCDN of logging information
related to the completion of any task performed by the dCDN on
behalf of the uCDN (e.g., delivery of the content to an end user)
or related to events happening in the dCDN that are relevant to
the uCDN (e.g., failures or unavailability in dCDN). This takes
place within the dCDN and does not directly involve CDNI
interfaces.
o communication by the dCDN to the uCDN of the logging information
collected by the dCDN relevant to the uCDN. This is supported by
the CDNI Logging interface and in the scope of the present
document. For example, the uCDN may use this logging information
to charge the CSP, to perform analytics and monitoring for
operational reasons, to provide analytics and monitoring views on
its content delivery to the CSP or to perform trouble-shooting.
o customization by the dCDN of the logging to be performed by the
uCDN on behalf of the dCDN. The mechanism to support the
customisation by the dCDN of CDNI Logging information is outside
the scope of this document and left for further study.
o generation and collection by the uCDN of logging information
related to the completion of any task performed by the uCDN on
behalf of the dCDN (e.g., serving of content by uCDN to dCDN for
acquisition purposes by dCDN) or related to events happening in
the uCDN that are relevant to the dCDN. This takes place within
the uCDN and does not directly involve CDNI interfaces.
o communication by the uCDN to the dCDN of the logging information
collected by the uCDN relevant to the dCDN. For example, the dCDN
might potentially benefit form this information for security
Bertrand, et al. Expires August 26, 2013 [Page 9]
Internet-Draft CDNI Logging February 2013
auditing or content acquisition troubleshooting. This is outside
the scope of this document and left for further study.
Figure 1 provides an example of CDNI Logging interactions (focusing
only on the interactions that are in the scope of this document) in a
particular scenario where 4 CDNs are involved in the delivery of
content from a given CSP: the uCDN has a CDNI interconnection with
dCDN-1 and dCDN-2. In turn, dCDN2 has a CDNI interconnection with
dCDN3. In this example, uCDN, dCDN-1, dCDN-2 and dCDN-3 all
participate in the delivery of content for the CSP. In this example,
the CDNI Logging interface enables the uCDN to obtain logging
information from all the dCDNs involved in the delivery. In the
example, uCDN uses the Logging data:
o to analyze the performance of the delivery operated by the dCDNs
and to adjust its operations (e.g., request routing) as
appropriate,
o to provide reporting (non real-time) and monitoring (real-time)
information to CSP.
For instance, uCDN merges Logging data, extracts relevant KPIs, and
presents a formatted report to the CSP, in addition to a bill for the
content delivered by uCDN itself or by its dCDNs on his behalf. uCDN
may also provide Logging data as raw log files to the CSP, so that
the CSP can use its own logging analysis tools.
Bertrand, et al. Expires August 26, 2013 [Page 10]
Internet-Draft CDNI Logging February 2013
+-----+
| CSP |
+-----+
^ Reporting and monitoring data
* Billing
,--*--.
Logging ,-' `-.
Data =>( uCDN )<= Logging
// `-. _,-' \\ Data
|| `-'-'-' ||
,-----. ,-----.
,-' `-. ,-' `-.
( dCDN-1 ) ( dCDN-2 )<== Logging
`-. ,-' `-. _,-' \\ Data
`--'--' `--'-' ||
,-----.
,' `-.
( dCDN-3 )
`. ,-'
`--'--'
===> CDNI Logging Interface
***> outside the scope of CDNI
Figure 1: Interactions in CDNI Logging Reference Model
A dCDN (e.g., dCDN-2) integrates the relevant logging information
obtained from its dCDNs (e.g., dCDN-3) in the logging information
that it provides to the uCDN, so that the uCDN ultimately obtains all
logging information relevant to a CSP for which it acts as the
authoritative CDN.
Note that the format of Logging information that a CDN provides over
the CDNI interface might be different from the one that the CDN uses
internally. In this case, the CDN needs to reformat the Logging
information before it provides this information to the other CDN over
the CDNI Logging interface. Similarly, a CDN might reformat the
Logging data that it receives over the CDNI Logging interface before
injecting it into its log-consuming applications or before providing
some of this logging information to the CSP. Such reformatting
operations introduce latency in the logging distribution chain and
introduce a processing burden. Therefore, there are benefits in
specifying CDNI Logging format that are suitable for use inside CDNs
and also are close to the CDN Log formats commonly used in CDNs
today.
Bertrand, et al. Expires August 26, 2013 [Page 11]
Internet-Draft CDNI Logging February 2013
2.2. Overall Logging Chain
This section discusses the overall logging chain within and across
CDNs to clarify how CDN Logging information is expected to fit in
this overall chain. Figure 2 illustrates the overall logging chain
within the dCDN, across CDNs using the CDNI Logging interface and
within the uCDN. Note that the logging chain illustrated in the
Figure is obviously only indicative and varies depending on the
specific environments. For example, there may be more or less
instantiations of each entity (i.e., there may be 4 Log consuming
applications in a given CDN). As another example, there may be one
instance of Rectification process per Log Consuming Application
instead of a shared one.
Log Consuming Log Consuming
App App
/\ /\
| |
Rectification--------
/\
|
Filtering
/\
|
Collection uCDN
/\ /\
| |
| Generation
|
CDNI Logging ---------------------------------------------
exchange
/\ Log Consuming Log Consuming
| App App
| /\ /\
| | |
Rectification Rectification---------
/\ /\
| |
Filtering
/\
|
Collection dCDN
/\ /\
| |
Generation Generation
Bertrand, et al. Expires August 26, 2013 [Page 12]
Internet-Draft CDNI Logging February 2013
Figure 2: CDNI Logging in the overall Logging Chain
The following subsections describe each of the processes potentially
involved in the logging chain of Figure 2.
2.2.1. Logging Generation and During-Generation Aggregation
CDNs typically generate logging information for all significant task
completions, events, and failures. Logs are typically generated by
many devices in the CDN including the surrogates, the request routing
system, and the control system.
The amount of Logging information generated can be huge. Therefore,
during contract negotiations, interconnected CDNs often agree on a
Logging retention duration, and optionally, on a maximum size of the
Logging data that the dCDN must keep. If this size is exceeded, the
dCDN must alert the uCDN but may not keep more Logs for the
considered time period. In addition, CDNs may aggregate logs and
transmit only summaries for some categories of operations instead of
the full Logging data. Note that such aggregation leads to an
information loss, which may be problematic for some usages of Logging
(e.g., debugging).
[I-D.brandenburg-cdni-has] discusses logging for HTTP Adaptive
Streaming (HAS). In accordance with the recommendations articulated
there, it is expected that a surrogate will generate separate logging
information for delivery of each chunk of HAS content. This ensures
that separate logging information can then be provided to
interconnected CDNs over the CDNI Logging interface. Still in line
with the recommendations of [I-D.brandenburg-cdni-has], the logging
information for per-chunck delivery may include some information (a
Content Collection IDentifier and a Session IDentifier as discussed
in Section 5) intended to facilitate subsequent post-generation
aggregation of per-chunk logs into per-session logs. Note that a CDN
may also elect to generate aggregate per-session logs when performing
HAS delivery, but this needs to be in addition to, and not instead
of, the per-chunk delivery logs. We note that this may be revisited
in future versions of this document.
Note that in the case of non real-time logging, the trigger of the
transmission or generation of the logging file appears to be a
synchronous process from a protocol standpoint. The implementation
algorithm can choose to enforce a maximum size for the logging file
beyound which the transmission is automatically triggered (and thus
allow for an asynchrounous transmission process).
Bertrand, et al. Expires August 26, 2013 [Page 13]
Internet-Draft CDNI Logging February 2013
2.2.2. Logging Collection
This is the process that continuously collects logs generated by the
log-generating entities within a CDN.
In a CDNI environment, in addition to collecting logging information
from log-generating entities within the local CDN, the Collection
process also collects logging information provided by another CDN, or
other CDNs, through the CDNI Logging interface. This is illustrated
in Figure 2 where we see that the Collection process of the uCDN
collects logging information from log-generating entities within the
uCDN as well as logging information coming through CDNI Logging
exchange with the dCDN through the CDNI Logging interface.
2.2.3. Logging Filtering
A CDN may require to only present different subset of the whole
logging information collected to various log-consuming applications.
This is achieved by the Filtering process.
In particular, the Filtering process can also filter the right subset
of information that needs to be provided to a given interconnected
CDN. For example, the filtering process in the dCDN can be used to
ensure that only the logging information related to tasks performed
on behalf of a given uCDN are made available to that uCDN (thereby
filtering all the logging information related to deliveries by the
dCDN of content for its own CSPs). Similarly, the Filtering process
may filter or partially mask some fields, for example, to protect End
Users' privacy when communicating CDNI Logging information to another
CDN. Filtering of logging information prior to communication of this
information to other CDNs via the CDNI Logging interface requires
that the downstream CDN can recognize the set of log records that
relate to each interconnected CDN.
The CDN will also filter some internal scope information such as
information related to its internal alarms (security, failures, load,
etc).
In some use cases described in [RFC6770], the interconnected CDNs do
not want to disclose details on their internal topology. The
filtering process can then also filter confidential data on the
dCDNs' topology (number of servers, location, etc.). In particular,
information about the requests served by every Surrogate may be
confidential. Therefore, the Logging information must be protected
so that data such as Surrogates' hostnames is not disclosed to the
uCDN. In the "Inter-Affiliates Interconnection" use case, this
information may be disclosed to the uCDN because both the dCDN and
the uCDN are operated by entities of the same group.
Bertrand, et al. Expires August 26, 2013 [Page 14]
Internet-Draft CDNI Logging February 2013
2.2.4. Logging Rectification and Post-Generation Aggregation
If Logging is generated periodically, it is important that the
sessions that start in one Logging period and end in another are
correctly reported. If they are reported in the starting period,
then the Logging of this period will be available only after the end
of the session, which delays the Logging generation.
A Logging rectification/update mechanism could be useful to reach a
good trade-off between the Logging generation delay and the Logging
accuracy. Depending on the selected Logging protocol(s), such
mechanism may be invaluable for real time Logging, which must be
provided rapidly and cannot wait for the end of operations in
progress.
In the presence of HAS, some log-consuming applications can benefit
from aggregate per-session logs. For example, for analytics, per-
session logs allow display of session-related trends which are much
more meaningful for some types of analysis than chunk-related trends.
In the case where the log-generating entities have generated during-
generation aggregate logs, those can be used by the applications. In
the case where aggregate logs have not been generated, the
Rectification process can be extended with a Post-Generation
Aggregation process that generates per-session logs from the per-
chunk logs, possibly leveraging the information included in the per-
chunk logs for that purpose (Content Collection IDentifier and a
Session IDentifier). However, in accordance with
[I-D.brandenburg-cdni-has], this document does not define exchange of
such aggregate logs on the CDNI Logging interface. We note that this
may be revisited in future versions of this document.
2.2.5. Log-Consuming Applications
2.2.5.1. Maintenance/Debugging
Logging is useful to permit the detection (and limit the risk) of
content delivery failures. In particular, Logging facilitates the
resolution of configuration issues.
To detect faults, Logging must enable the reporting of any CDN
operation success and failure, such as request redirection, content
acquisition, etc. The uCDN can summarize such information into KPIs.
For instance, Logging format should allow the computation of the
number of times during a given epoch that content delivery related to
a specific service succeeds/fails.
Logging enables the CDN providers to identify and troubleshoot
performance degradations. In particular, Logging enables the
Bertrand, et al. Expires August 26, 2013 [Page 15]
Internet-Draft CDNI Logging February 2013
communication of traffic data (e.g., the amount of traffic that has
been forwarded by a dCDN on behalf of an uCDN over a given period of
time), which is particularly useful for CDN and network planning
operations.
2.2.5.2. Accounting
Logging is essential for accounting, to permit inter-CDN billing and
CSP billing by uCDNs. For instance, Logging enables the uCDN to
check the total amount of traffic delivered by every dCDN and for
every Delivery Service, as well as, the associated bandwidth usage
(e.g., peak, 95th percentile), and the maximum number of simultaneous
sessions over a given period of time.
2.2.5.3. Analytics and Reporting
The goal of analytics is to gather any relevant information to track
audience, analyze user behavior, and monitor the performance and
quality of content delivery. For instance, Logging enables the CDN
providers to report on content consumption (e.g., delivered sessions
per content) in a specific geographic area.
The goal of reporting is to gather any relevant information to
monitor the performance and quality of content delivery and allow
detection of delivery issues. For instance, reporting could track
the average delivery throughput experienced by End-Users in a given
region for a specific CSP or content set over a period of time.
2.2.5.4. Security
The goal of security is to prevent and monitor unauthorized access,
misuse, modification, and denial of access of a service. A set of
information is logged for security purposes. In particular, a record
of access to content is usually collected to permit the CSP to detect
infringements of content delivery policies and other abnormal End
User behaviors.
2.2.5.5. Legal Logging Duties
Depending on the country considered, the CDNs may have to retain
specific Logging information during a legal retention period, to
comply with judicial requisitions.
2.2.5.6. Notions common to multiple Log Consuming Applications
Bertrand, et al. Expires August 26, 2013 [Page 16]
Internet-Draft CDNI Logging February 2013
2.2.5.6.1. Logging Information Views
Within a given log-consuming application, different views may be
provided to different users depending on privacy, business, and
scalability constraints.
For example, an analytics tool run by the uCDN can provide one view
to an uCDN operator that exploits all the logging information
available to the uCDN, while the tool may provide a different view to
each CSP exploiting only the logging information related to the
content of the given CSP.
As another example, maintenance and debugging tools may provide
different views to different CDN operators, based on their
operational role.
2.2.5.6.2. Key Performance Indicators (KPIs)
This section presents, for explanatory purposes, a non-exhaustive
list of Key Performance Indicators (KPIs) that can be extracted/
produced from logs.
Multiple log-consuming applications, such as analytics, monitoring,
and maintenance applications, often compute and track such KPIs.
In a CDNI environment, depending on the situation, these KPIs may be
computed by the uCDN or by the dCDN. But it is usually the uCDN that
computes KPIs, because uCDN and dCDN may have different definitions
of the KPIs and the computation of some KPIs requires a vision of all
the deliveries performed by the uCDN and all its dCDNs.
Here is a list of important examples of KPIs:
o Number of delivery requests received from End-Users in a given
region for each piece of content, during a given period of time
(e.g., hour/day/week/month)
o Percentage of delivery successes/failures among the aforementioned
requests
o Number of failures listed by failure type (e.g., HTTP error code)
for requests received from End Users in a given region and for
each piece of content, during a given period of time (e.g., hour/
day/week/month)
o Number and cause of premature delivery termination for End Users
in a given region and for each piece of content, during a given
period of time (e.g., hour/day/week/month)
Bertrand, et al. Expires August 26, 2013 [Page 17]
Internet-Draft CDNI Logging February 2013
o Maximum and mean number of simultaneous sessions established by
End Users in a given region, for a given Delivery Service, 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 Delivery Service, 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 Delivery
Service, and during a given period of time (e.g., hour/day/week/
month)
o Cache-hit and byte-hit ratios for requests received from End Users
in a given region for each piece of content, during a given period
of time (e.g., hour/day/week/month)
o Top 10 of the most popularly requested content (during a given
day/week/month),
o Terminal type (mobile, PC, STB, if this information can be
acquired from the browser type header, for example).
Additional KPIs can be computed from other sources of information
than the Logging, for instance, data collected by a content portal or
by specific client-side APIs. Such KPIs are out of scope for the
present memo.
The KPIs used depend strongly on the considered log-consuming
application -- the CDN operator may be interested in different
metrics than the CSP is. In particular, CDN operators are often
interested in delivery and acquisition performance KPIs, information
related to Surrogates' performance, caching information to evaluate
the cache-hit ratio, information about the delivered file size to
compute the volume of content delivered during peak hour, etc.
Some of the KPIs, for instance those providing an instantaneous
vision of the active sessions for a given CSP's content, are useful
essentially if they are provided in real-time. By contrast, some
other KPIs, such as the one averaged on a long period of time, can be
provided in non-real time.
3. CDNI Logging Transport Requirements
Bertrand, et al. Expires August 26, 2013 [Page 18]
Internet-Draft CDNI Logging February 2013
3.1. Timeliness
Some applications consuming CDNI Logging information, such as
accounting or trend analytics, only require logging information to be
available with a timeliness of the order of a day or the hour. This
document focuses on addressing this requirement.
Some applications consuming CDNI Logging information, such as real-
time analytics, require logging information to be available in real-
time (i.e. of the order of a second after the corresponding event).
This document leaves this requirement out of scope.
3.2. Reliability
CDNI logging information must be transmitted reliably. The transport
protocol should contain an anti-replay mechanism.
3.3. Security
CDNI logging information exchange must allow authentication,
integrity protection, and confidentiality protection. Also, a non-
repudiation mechanism is mandatory, the transport protocol should
support it.
3.4. Scalability
CDNI logging information exchange must support large scale
information exchange, particularly so in the presence of HTTP
Adaptive Streaming.
For example, if we consider a client pulling HTTP Progressive
Download content with an average duration of 10 minutes, this
represents 1/600 CDNI delivery Logging Records per second. If we
assume the dCDN is simultaneously serving 100,000 such clients on
behalf of the uCDN, the dCDN will be generating 167 Logging Records
per second to be communicated to the uCDN over the CDNI Logging
interface. Or equivalently, if we assume an average delivery rate of
2Mb/s, the dCDN generates 0.83 CDNI Logging Records per second for
every Gb/s of streaming on behalf of the uCDN.
For example, if we consider a client pulling HAS content and
receiving a video chunk every 2 seconds, a separate audio chunck
every 2 seconds and a refreshed manifest every 10 seconds, this
represents 1.1 delivery Logging Record per second. If we assume the
dCDN is simultaneously serving 100,000 such clients on behalf of the
uCDN, the dCDN will be generating 110,000 Logging Records per second
to be communicated to the uCDN over the CDNI Logging interface. Or
equivalently, if we assume an average delivery rate of 2Mb/s, the
Bertrand, et al. Expires August 26, 2013 [Page 19]
Internet-Draft CDNI Logging February 2013
dCDN generates 550 CDNI Logging Records per second for every Gb/s of
streaming on behalf of the uCDN.
3.5. Consistency between CDNI Logging and CDN Logging
There are benefits in using a CDNI logging format as close as
possible to intra-CDN logging format commonly used in CDNs tody in
order to minimize systematic translation at CDN/CDNI boundary.
3.6. Dispatching/Filtering
When a CDN is acting as a dCDN for multiple uCDNs, the dCDN needs to
dispatch each CDNI Logging Record to the uCDN that redirected the
corresponding request. The CDNI Logging format need to allow, and
possibly facilitate, such a dispatching.
4. CDNI Logging Information Structure and Transport
As defined in Section 1.1 a CDNI logging field is as an atomic
logging information element and a CDNI Logging Record is a collection
of CDNI Logging Fields containing all logging information
corresponding to a single logging event.
This document defines non-real-time transport of CDNI Logging
information over the CDNI interface. For such non-real-time
transport, this documents defines a third level of structure, the
CDNI Logging File, that is a collection of CDNI Logging Records.
This structure is described in Figure 3. This document then
specifies how to transport such CDNI Logging Files across
interconnected CDNs. We observe that this approach can be tuned in a
real deployment to achieve near-real time exchange of CDNI Logging
information, e.g., by increasing the frequency of logging file
creation and distribution throughout the Logging chain, but it is not
expected that this approach can support real time transport (e.g.,
sub-second) of CDNI logging information.
Bertrand, et al. Expires August 26, 2013 [Page 20]
Internet-Draft CDNI Logging February 2013
+------------------------------------------------------+
|CDNI Logging File |
| |
| +--------------------------------------------------+ |
| |CDNI Logging Record | |
| | +-------------+ +-------------+ +-------------+ | |
| | |CDNI Logging | |CDNI Logging | |CDNI Logging | | |
| | | Field | | Field | | Field | | |
| | +-------------+ +-------------+ +-------------+ | |
| +--------------------------------------------------+ |
| |
| +--------------------------------------------------+ |
| |CDNI Logging Record | |
| | +-------------+ +-------------+ +-------------+ | |
| | |CDNI Logging | |CDNI Logging | |CDNI Logging | | |
| | | Field | | Field | | Field | | |
| | +-------------+ +-------------+ +-------------+ | |
| +--------------------------------------------------+ |
| |
| +--------------------------------------------------+ |
| |CDNI Logging Record | |
| | +-------------+ +-------------+ +-------------+ | |
| | |CDNI Logging | |CDNI Logging | |CDNI Logging | | |
| | | Field | | Field | | Field | | |
| | +-------------+ +-------------+ +-------------+ | |
| +--------------------------------------------------+ |
+------------------------------------------------------+
Figure 3: Structure of Logging Files
It is expected that future version of this document will also specify
real time transport of CDNI Logging information over the CDNI
interface. We note that this might involve direct transport of CDNI
Logging Records without prior grouping into a file structure to avoid
the latency associated with creating and transporting such a file
structure throughout the logging chain.
The semantics and encoding of the CDNI Logging fields are specified
in Section 5. The semantics and encoding of CDNI Records are
specified in Section 6. The CDNI Logging File format is specified in
Section 7. The protocol for transport of CDNI Logging File is
specified in Section 8.
Bertrand, et al. Expires August 26, 2013 [Page 21]
Internet-Draft CDNI Logging February 2013
5. CDNI Logging Fields
Existing CDNs Logging functions collect and consolidate logs
performed by their Surrogates. Surrogates usually store the logs
using a format derived from Web servers' and caching proxies' log
standards such as W3C, NCSA [ELF] [CLF], or Squid format [squid]. In
practice, these formats are adapted to cope with CDN specifics.
Appendix A presents examples of commonly used log formats.
5.1. Semantics of CDNI Logging Fields
This section specifies the semantics of the CDNI Logging Fields. The
specific subset of CDNI Logging fields that can be found in each type
of Logging Record is specified in Section 6.
The semantics of the CDNI Logging Fields are specified in Table 1.
Bertrand, et al. Expires August 26, 2013 [Page 22]
Internet-Draft CDNI Logging February 2013
+--------------+----------------------------------------------------+
| Name | Description |
+--------------+----------------------------------------------------+
| Start-time | A start date and time associated with a logged |
| | event; for instance, the time at which a Surrogate |
| | received a content delivery request or the time at |
| | which an origin server received a content |
| | acquisition request. |
| End-time | An end date and time associated with a logged |
| | event. For instance, the time at which a |
| | Surrogate completed the handling of a content |
| | delivery request (e.g., end of delivery or error). |
| Duration | The duration of an operation in milliseconds. For |
| | instance, this field could be used to provide the |
| | time it took the Surrogate to send the requested |
| | file to the End-User or the time it took the |
| | Surrogate to acquire the file on a cache-miss |
| | event. In the case where Start-time, End-time, |
| | and Duration appear in a Logging Record, the |
| | Duration is to be interpreted as a total activity |
| | time related to the logged operation. |
| Client-IP | The IP address of the User Agent that issued the |
| | logged request or of a proxy, for instance |
| | "203.0.113.1". |
| Client-port | The source port of the logged request (e.g., 9542) |
| Destination- | The IP address of the host that received the |
| IP | logged request (e.g., 192.0.2.2). |
| Destination- | The hostname of the host that received the logged |
| hostname | request (e.g., Surrogate1.cdna.com). |
| Destination- | The destination port of the logged request (e.g., |
| port | 80). |
| Operation | The kind of operation that is logged; for instance |
| | Delivery or Purging. |
| URI_full | The full requested URL (e.g., |
| | "http://node1.peer-a.op-b.net/cdn.csp.com/movies/p |
| | otter.avi?param=11&user=toto"). When HTTP request |
| | redirection is used, this URI includes the |
| | Surrogate FQDN. If the association of requests t |
| | oSurrogates is confidential, the dCDN can present |
| | only URI_part to uCDN. |
Bertrand, et al. Expires August 26, 2013 [Page 23]
Internet-Draft CDNI Logging February 2013
| URI_part | The requested URL path (e.g., |
| | /cdn.csp.com/movies/potter.avi?param=11&user=toto |
| | if the full request URL was |
| | "http://node1.peer-a.op-b.net/cdn.csp.com/movies/p |
| | otter.avi?param=11&user=toto"). The URI without |
| | host-name typically includes the "CDN domain" |
| | (ex.cdn.csp.com) - cf. [I-D.ietf-cdni-framework]: |
| | it enables the identification of the CSP service |
| | agreed between the CSP and the CDNP operating the |
| | uCDN. |
| Protocol | The protocol and protocol version of the message |
| | that triggered the Logging entry (e.g., HTTP/1.1). |
| Request-meth | The protocol method of the request message that |
| od | triggered the Logging entry. |
| Status | The protocol status of the reply message related |
| | to the Logging entry |
| Bytes-Sent | The number of bytes at application-layer |
| | protocol-level (e.g., HTTP) of the reply message |
| | related to the Logging entry. It includes the |
| | size of the response headers. |
| Headers-Sent | The number of bytes corresponding to response |
| | headers at application-layer protocol-level (e.g., |
| | HTTP) of the reply message related to the Logging |
| | entry. |
| Bytes-receiv | The number of bytes (headers + body) of the |
| ed | message that triggered the Logging entry. |
| Referrer | The value of the Referrer header in an HTTP |
| | request. |
| User-Agent | The value of the User Agent header in an HTTP |
| | request. |
| Cookie | The value of the Cookie header in an HTTP request. |
| Byte-Range | [Ed. note: to be defined] |
| Cache-contro | The value of the cache-control header in an HTTP |
| l | answer. This header is particularly important for |
| | content acquisition logs. |
| Record-diges | A digest of the Logging Record; it enables |
| t | detecting corrupted Logging Records. |
| CCID | A Content Collection IDentifier (CCID) eases the |
| | correlation of several Logging Records related to |
| | a Content Collection (e.g., a movie split in |
| | chunks). |
| SID | A Session Identifier (SID) eases the correlation |
| | (and aggregation) of several Logging Records |
| | related to a session. The SID is especially |
| | relevant for summarizing HAS Logging information |
| | [I-D.brandenburg-cdni-has]. |
Bertrand, et al. Expires August 26, 2013 [Page 24]
Internet-Draft CDNI Logging February 2013
| uCDN-ID | An element authenticating the operator of the uCDN |
| | as the authority having delegated the request to |
| | the dCDN. |
| Delivering-C | An identifier (e.g., an aggregation of an IP |
| DN-ID | address and a FQDN) of the Delivering CDN. The |
| | Delivering-CDN-ID might be considered as |
| | confidential by the dCDN. In such case, the dCDN |
| | could either not provide this field to the uCDN or |
| | overwrite the Delivering-CDN-ID with its on |
| | identifier. |
| Cache-bytes | The number of body bytes served from caches. This |
| | quantity permits the computation of the byte hit |
| | ratio. |
| Action | The Action describes how a given request was |
| | treated locally: through which transport protocol, |
| | with or without content revalidation, with a cache |
| | hit or cache miss, with fresh or stale content, |
| | and (if relevant) with which error. Example with |
| | Squid format [squid]: "TCP_REFRESH_FAIL_HIT" means |
| | that an expired copy of an object requested |
| | through TCP was in the cache. Squid attempted to |
| | make an If-Modified-Since request, but it failed. |
| | The old (stale) object was delivered to the |
| | client. |
| MIME-Type | The MIME-Type of the requested content |
| dCDN | An element authenticating the operator of the dCDN |
| identifier | as the authority requesting the content to the |
| | uCDN |
| Caching_date | Date at which the delivered content was stored in |
| | cache |
| Validity_hea | A copy of all headers related to content validity: |
| ders | Pragma or Cache-Control (no-cache), ETag, Vary, |
| | last-modified... |
| Lookup_durat | Duration of the DNS resolution for resolving the |
| ion | FQDN of (uCDN's or CSP's) origin server. |
| Delay_to_fir | Duration of the operations from the sending of the |
| st_bit | content acquisition request to the reception of |
| | the first bit of the requested content. |
| Delay_to_las | Duration of the operations from the sending of the |
| t_bit | content acquisition request to the reception of |
| | the last bit of the requested content. |
+--------------+----------------------------------------------------+
Table 1: Semantics of CDNI Logging Fields
NB: we define three fields related to the timing of logged
operations: Start-time, End-time, and Duration. Start-time is
typically useful for human readers (e.g., while debugging), however,
Bertrand, et al. Expires August 26, 2013 [Page 25]
Internet-Draft CDNI Logging February 2013
some servers log the operation's End-time which corresponds to the
time of log record generation. In absence of Logging summarization,
only two of these three fields are required to obtain relevant timing
information on the operation. However, when some kind of Logging
aggregation/summarization is used, it can be advantageous to keep the
three fields: for instance, in the case of HAS, keeping the three
fields permits computing an average delivery bitrate from a single
Logging Record aggregating information on the delivery of multiple
consecutive video chunks.
Multiple header fields, in addition to the ones explicitly listed in
the table could be reproduced in the Logging records.
Note that uCDN may want to filter Logging data by user (and not by IP
address) to provide more relevant information to the CSP. In such
case, a user may be identified as a combination of several pieces of
information such as the client IP and User Agent or through the SID.
The URI_full provides information on the Surrogate that provided the
content. This information can be relevant, for instance, for the
Inter-Affiliates use case described in [RFC6770]. However, in some
cases it may be considered as confidential and the dCDN may provide
URI_part instead.
Other information that could be logged include operations that refer
to the general state of the request, before it gets processed
locally. Such information is related to the authorization of the
requests, URL rewriting rules enforced, the X-FORWARDED-FOR non
standard HTTP header...
[Editor's Note: CDNI Logging information may be used for debugging.
Therefore, various CDN operations might be logged, depending on the
agreement between the dCDN and the uCDN, such as operations related
to Request Routing and Metadata. These may call for a few additional
Fields to be defined].
5.2. Syntax of CDNI Logging Fields
This section is intended to contain the specification for the syntax
and encoding of the CDNI Logging fields. For now, Table 2
illustrates the definition of some information elements. It provides
examples using Apache log format strings [apache] when they exist.
[Ed. note: specify for all Logging Fields the type (e.g., varchar,
int, float, ...) and the maximum size (e.g., varchar(200))]
Bertrand, et al. Expires August 26, 2013 [Page 26]
Internet-Draft CDNI Logging February 2013
+----------+-------------------+------------------------------------+
| Name | String | Example |
+----------+-------------------+------------------------------------+
| Time | %t | [10/Oct/2000:13:55:36-0700] |
| Duration | %D | - |
| Client-I | %a | 203.0.113.45 |
| P | | |
| Operatio | - | - |
| n | | |
| URI_full | %U | - |
| Protocol | %H | HTTP/1.0 |
| Request | %m | GET |
| method | | |
| Status | %>s | 200 |
| Bytes | %O | 2326 |
| Sent | | |
| Bytes | %I | 432 |
| received | | |
| Header | \"%{Referrer}i\" | "http://www.example.com/start.html |
| | \"%{User-agent}i\ | ""Mozilla/4.08 [en] (Win98; I |
| | " | ;Nav)" |
+----------+-------------------+------------------------------------+
Table 2: Examples using Apache format
6. CDNI Logging Records
[Ed. note: we need to specify the encoding of the file, the
separation character, etc...]
This section defines the events for which a CDNI Logging record can
be exchanged over the CDNI Logging interafce and for each type of
Logging Record indicates the allowed set of CDNI Information
Elements.
We classify the logged events depending on the CDN operation to which
they relate: Content Delivery, Content Acquisition, Content
Invalidation/Purging, etc.
6.1. Content Delivery
The content delivery event triggering the generation of a Logging
Record include:
o Reception by a dCDN Surrogate of a content request
The Logging Record for Content Delivery contains the following set of
Bertrand, et al. Expires August 26, 2013 [Page 27]
Internet-Draft CDNI Logging February 2013
CDNI Logging Elements:
+----------------------+--------------------------------------------+
| Name | Mandatory/Optional |
+----------------------+--------------------------------------------+
| Start-time | Mandatory |
| Duration | Mandatory |
| Client-IP | Mandatory |
| Client-port | Optional |
| Destination-IP | Mandatory if Destination-Hostname is |
| | absent |
| Destination-Hostname | Mandatory if Destination-IP is absent |
| Destination-port | Optional |
| Operation | Optional |
| URI_full | Mandatory if URI_part is absent |
| URI_part | Mandatory if URI_full is absent |
| Protocol | Mandatory if protocol is different to |
| | HTTP/1.1 |
| Request-method | Mandatory |
| Status | Mandatory |
| Bytes-Sent | Mandatory |
| Headers-Sent | Optional |
| Bytes-received | Optional |
| Referrer | Optional |
| User-Agent | Optional |
| Cookie | Optional |
| Byte-Range | ? |
| Cache-control | Optional |
| Record-digest | ? |
| CCID | Optional. Only applicable to HTTP |
| | Adaptive Streaming delivery. |
| SID | Optional. Only applicable to HTTP |
| | Adaptive Streaming delivery. |
| Cache-bytes | Optional |
| Action | Mandatory (in particulat re cache |
| | Hit/Miss) |
| MIME-Type | Mandatory |
+----------------------+--------------------------------------------+
Table 3: CDNI Logging Fields in Delivery Logging Record
In Table 3, "Mandatory" means that this field MUST be included in
each Delivery Record and "Optional" means that it can be included
based on the agreement between the dCDN and the uCDN as established
via mechanism outside the scope of this document (e.g., by human
agreement).
Bertrand, et al. Expires August 26, 2013 [Page 28]
Internet-Draft CDNI Logging February 2013
6.2. Content Invalidation and Purging
Given that the Purge interface is expected to contain a mechanism to
report on completion of the Invalidation/purge request, there is no
need to specify separate Log Records for these events.
6.3. Request Routing
[Editor's Note: Is there a requirement for the dCDN to provide logs
for request routing events?]
6.4. Logging Extensibility
Future usages might introduce the need for additional Logging fields.
In addition, some use-cases such as an Inter-Affiliate
Interconnection [RFC6770], might take advantage of extended Logging
exchanges. Therefore, it is important to permit CDNs to use
additional Logging fields besides the standard ones, if they want.
For instance, an "Account-name" identifying the contract enforced by
the dCDN for a given request could be provided in extended fields.
The required Logging Records may depend on the considered services.
For instance, static file delivery (e.g., pictures) typically does
not include any delivery restrictions. By contrast, video delivery
typically implies strong content delivery restrictions, as explained
in [RFC6770], and Logging could include information about the
enforcement of these restrictions. Therefore, to ease the support of
varied services as well as of future services, the Logging interface
should support optional Logging Records.
7. CDNI Logging File Format
Interconnected CDNs may support various Logging formats. However,
they must support at least the default Logging File format described
here.
7.1. Logging Files
[Ed. Note: How many files (one per type of Delivery Service (e.g.,
HTTP, WMP) and per type of Event (e.g., Errors, Delivery,
Acquisition,...?)and what would be inside... These aspects needs to
be detailed...]
7.2. File Format
The Logging file format should be independent from the selected
transport protocol, to guarantee a flexible choice of transport
Bertrand, et al. Expires August 26, 2013 [Page 29]
Internet-Draft CDNI Logging February 2013
protocols. [Ed. note: for the real time Logging exchanges, this
might be hard]
All Logging Records in a Logging File must share the same format
(same set of Logging Fields, in the same order, with the same
semantics, separated by the same Separator Character), to ease the
parsing of the Logging data by the CDN that receives the Logging
File. The CDN that provides the Logging data is responsible for
guaranteeing the consistency of the Logging records' formats,
typically via its log filtering and aggregation processes (see
Section 2.2.3).
7.2.1. Headers
Logging files must include a header with the information described in
Figure 4.
+----------------+-------------------+------------------------------+
| Field | Description | Examples |
+----------------+-------------------+------------------------------+
| Format | Identification of | standard_cdni_errors_http_v1 |
| | CDNI Log format. | |
| Fields | A description of | |
| | the record format | |
| | (list of fields). | |
| Log-ID | Identifier | abcdef1234 |
| | for the CDNI Log | |
| | file (facilitates | |
| | detection of | |
| | duplicate Logs | |
| | and tracking in | |
| | case of | |
| | aggregation). | |
| Log-Timestamp | Time, in | [20/Feb/2012:00:29.510+0200] |
| | milliseconds, the | |
| | CDNI Log was | |
| | generated. | |
| Log-Origin | Identifier of the | cdn1.cdni.example.com |
| | authority (e.g., | |
| | dCDN or uCDN) | |
| | providing the Log-| |
| | -ging | |
+----------------+-------------------+------------------------------+
Figure 4: Logging Headers
Bertrand, et al. Expires August 26, 2013 [Page 30]
Internet-Draft CDNI Logging February 2013
All time-related Logging Fields and data in the Logging File headers/
footers must provide a time zone and be at least at millisecond (ms)
accuracy. The accuracy must be consistent to permit the computation
of KPIs involving operations realized on several CDNs.
[Ed. note: would it make sense to add a kind of "example Logging
Record" in the Logging file and associated semantic (e.g., in a
structure data format) ?]
7.2.2. Body (Logging Records) Format
[Ed. note: the W3C extended log format is a good base candidate to
look at. ]
Since records for real time information and non-real time information
could use different formats, we do not yet solve the problem of real
time logging exchanges in this version.
7.2.3. Footer Format
Logging files must include a footer with the information described in
Figure 5.
+---------+----------------------------------------------+----------+
| Field | Description | Examples |
+---------+----------------------------------------------+----------+
| Log | Digest of the complete Log (facilitates | |
| Digest | detection of Log corruption) | |
+---------+----------------------------------------------+----------+
Figure 5: Logging footers
This digest field permits the detection of corrupted Logging files.
This can be useful, for instance, if a problem occurs on the
filesystem of the dCDN Logging system and leads to a truncation of a
logging file. Additional mechanisms to avoid corrupted Logging files
are expected to be provided by the Logging transport protocol, cf.
Section 8.
8. CDNI Logging File Transport Protocol
As presented in [RFC6707], several protocols already exist that could
potentially be used to exchange CDNI Logging between interconnected
CDNs.
Bertrand, et al. Expires August 26, 2013 [Page 31]
Internet-Draft CDNI Logging February 2013
The offline exchange of non real-time Logging could rely on several
protocols. In particular, the dCDN could publish the Logging on a
server where the uCDN would retrieve them using a secure protocol.
For managed file transfer, the recommended protocol is SSH File
Transfer Protocol (SFTP) [I-D.ietf-secsh-filexfer]. SFTP is widely
deployed and it guarantees the respect of the criteria expressed by
the CDNI Logging Transport Requirements: timeliness, reliability,
security and scalability.
[Ed note: include options for lossless compression]
9. Open Issues
The main remaining tasks on this ID are the following:
o Finalise the list of CDNI Logging Fields
o Finalise the encoding of CDNI Logging Fields, Records and File.
o Identify what can be done (if anything) to maximise reuse of
Logging Fields and Logging Records encoding for future support of
real-time CDNI Logging exchange
[Ed. Note: The format for Time is still to be agreed on. RFC 5322
(Section 3.3) format could be used or ISO 8601 formatted date and
time in UTC (same format as proposed in
[draft-caulfield-cdni-metadata-core-00]). Also see RFC5424 Section
6.2.3.]
[Ed. note: (comment from Kevin) how are errors handled ? If the
client gets handed a bunch of 403s and 404s, but still gets the
content eventually, without triggering an event, are those still
logged? For Bytes-Sent, if there were aborted requests, do those get
counted as well? Not all client behavior can be correlated with the
simplified log]
10. IANA Considerations
TBD
11. Security Considerations
Bertrand, et al. Expires August 26, 2013 [Page 32]
Internet-Draft CDNI Logging February 2013
11.1. Privacy
CDNs have the opportunity to collect detailed information about the
downloads performed by End-Users. The provision of this information
to another CDN introduces End-Users privacy protection concerns.
11.2. Non Repudiation
Logging provides the raw material for charging. It permits the dCDN
to bill the uCDN for the content deliveries that the dCDN makes on
behalf of the uCDN. It also permits the uCDN to bill the CSP for the
content Delivery Service. Therefore, non-repudiation of Logging data
is essential.
12. Acknowledgments
The authors would like to thank Sebastien Cubaud, Anne Marrec,
Yannick Le Louedec, and Christian Jacquenet for detailed feedback on
early versions of this document and for their input on existing Log
formats.
The authors would like also to thank Fabio Costa, Sara Oueslati, Yvan
Massot, Renaud Edel, and Joel Favier for their input and comments.
Finally, they thank the contributors of the EU FP7 OCEAN project for
valuable inputs.
13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009.
13.2. Informative References
[CLF] A. Luotonen, "The Common Log-file Format, W3C (work in
progress)", 1995, <http://www.w3.org/pub/WWW/Daemon/User/
Config/Logging.html>.
[ELF] Phillip M. Hallam-Baker and Brian Behlendorf, "Extended
Log File Format, W3C (work in progress), WD-logfile-
960323", <http://www.w3.org/TR/WD-logfile.html>.
Bertrand, et al. Expires August 26, 2013 [Page 33]
Internet-Draft CDNI Logging February 2013
[I-D.brandenburg-cdni-has]
Brandenburg, R., Deventer, O., Faucheur, F., and K. Leung,
"Models for adaptive-streaming-aware CDN Interconnection",
draft-brandenburg-cdni-has-04 (work in progress),
January 2013.
[I-D.ietf-cdni-framework]
Peterson, L. and B. Davie, "Framework for CDN
Interconnection", draft-ietf-cdni-framework-03 (work in
progress), February 2013.
[I-D.ietf-cdni-requirements]
Leung, K. and Y. Lee, "Content Distribution Network
Interconnection (CDNI) Requirements",
draft-ietf-cdni-requirements-04 (work in progress),
December 2012.
[I-D.ietf-secsh-filexfer]
Galbraith, J. and O. Saarenmaa, "SSH File Transfer
Protocol", draft-ietf-secsh-filexfer-13 (work in
progress), July 2006.
[RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content
Distribution Network Interconnection (CDNI) Problem
Statement", RFC 6707, September 2012.
[RFC6770] Bertrand, G., Stephan, E., Burbridge, T., Eardley, P., Ma,
K., and G. Watson, "Use Cases for Content Delivery Network
Interconnection", RFC 6770, November 2012.
[apache] "Apache 2.2 log files documentation", Feb. 2012,
<http://httpd.apache.org/docs/current/logs.html>.
[squid] "Squid Log-Format documentation", Feb. 2012,
<http://wiki.squid-cache.org/SquidFaq/SquidLogs>.
Appendix A. Examples Log Format
This section provides example of log formats implemented in existing
CDNs, web servers, and caching proxies.
Web servers (e.g., Apache) maintain at least one log file for logging
accesses to content (the Access Log). They can typically be
configured to log errors in a separate log file (the Error Log). The
log formats can be specified in the server's configuration files.
However, webmasters often use standard log formats to ease the log
processing with available log analysis tools.
Bertrand, et al. Expires August 26, 2013 [Page 34]
Internet-Draft CDNI Logging February 2013
A.1. W3C Common Log File (CLF) Format
The Common Log File (CLF) format defined by the World Wide Web
Consortium (W3C) working group is compatible with many log analysis
tools and is supported by the main web servers (e.g., Apache) Access
Logs.
According to [CLF], the common log-file format is as follows:
remotehost rfc931 authuser [date] "request" status bytes.
Example (from [apache]): 127.0.0.1 - frank [10/Oct/2000:13:55:36
-0700] "GET /apache_pb.gif HTTP/1.0" 200 2326
The fields are defined as follows [CLF]:
+------------+------------------------------------------------------+
| Element | Definition |
+------------+------------------------------------------------------+
| remotehost | Remote hostname (or IP number if DNS hostname is not |
| | available, or if DNSLookup is Off. |
| rfc931 | The remote logname of the user. |
| authuser | The username that the user employed to authenticate |
| | himself. |
| [date] | Date and time of the request. |
| "request" | An exact copy of the request line that came from the |
| | client. |
| status | The status code of the HTTP reply returned to the |
| | client. |
| bytes | The content-length of the document transferred. |
+------------+------------------------------------------------------+
Table 4: Information elements in CLF format
A.2. W3C Extended Log File (ELF) Format
The Extended Log File (ELF) format defined by W3C extends the CLF
with new fields. This format is supported by Microsoft IIS 4.0 and
5.0.
The supported fields are listed below [ELF].
Bertrand, et al. Expires August 26, 2013 [Page 35]
Internet-Draft CDNI Logging February 2013
+------------+---------------------------------------------------+
| Element | Definition |
+------------+---------------------------------------------------+
| date | Date at which transaction completed |
| time | Time at which transaction completed |
| time-taken | Time taken for transaction to complete in seconds |
| bytes | bytes transferred |
| cached | Records whether a cache hit occurred |
| ip | IP address and port |
| dns | DNS name |
| status | Status code |
| comment | Comment returned with status code |
| method | Method |
| uri | URI |
| uri-stem | Stem portion alone of URI (omitting query) |
| uri-query | Query portion alone of URI |
+------------+---------------------------------------------------+
Table 5: Information elements in ELF format
Some fields start with a prefix (e.g., "c-", "s-"), which explains
which host (client/server/proxy) the field refers to.
o Prefix Description
o c- Client
o s- Server
o r- Remote
o cs- Client to Server.
o sc- Server to Client.
o sr- Server to Remote Server (used by proxies)
o rs- Remote Server to Server (used by proxies)
Example: date time s-ip cs-method cs-uri-stem cs-uri-query s-port cs-
username c-ip cs(User-Agent) sc-status sc-substatus sc-win32-status
time-taken
2011-11-23 15:22:01 x.x.x.x GET /file 80 y.y.y.y Mozilla/
5.0+(Windows;+U;+Windows+NT+6.1;+en-US;+rv:1.9.1.6)+Gecko/
20091201+Firefox/3.5.6+GTB6 200 0 0 2137
Bertrand, et al. Expires August 26, 2013 [Page 36]
Internet-Draft CDNI Logging February 2013
A.3. National Center for Supercomputing Applications (NCSA) Common Log
Format
This format for Access Logs offers the following fields:
o host rfc931 date:time "request" statuscode bytes
o x.x.x.x userfoo [10/Jan/2010:21:15:05 +0500] "GET /index.html
HTTP/1.0" 200 1043
A.4. NCSA Combined Log Format
The NCSA Combined log format is an extension of the NCSA Common log
format with three (optional) additional fields: the referral field,
the user_agent field, and the cookie field.
o host rfc931 username date:time request statuscode bytes referrer
user_agent cookie
o Example: x.x.x.x - userfoo [21/Jan/2012:12:13:56 +0500] "GET
/index.html HTTP/1.0" 200 1043 "http://www.example.com/" "Mozilla/
4.05 [en] (WinNT; I)" "USERID=CustomerA;IMPID=01234"
A.5. NCSA Separate Log Format
The NCSA Separate log format refers to a log format in which the
information gathered is separated into three separate files. This
way, every entry in the Access Log (in the NCSA Common log format) is
complemented with an entry in a Referral log and another one in an
Agent log. These three records can be correlated easily thanks to
the date:time value. The format of the Referral log is as follows:
o date:time referrer
o Example: [21/Jan/2012:12:13:56 +0500]
"http://www.example.com/index.html"
The format of the Agent log is as follows:
o date:time agent
o [21/Jan/2012:12:13:56 +0500] "Microsoft Internet Explorer - 5.0"
A.6. Squid 2.0 Native Log Format for Access Logs
Squid [squid] is a popular piece of open-source software for
transforming a Linux host into a caching proxy. Variations of Squid
log format are supported by some CDNs.
Bertrand, et al. Expires August 26, 2013 [Page 37]
Internet-Draft CDNI Logging February 2013
Squid common access log format is as follow: time elapsed remotehost
code/status bytes method URL rfc931 peerstatus/peerhost type.
Squid also supports a more detailed native access log format:
Timestamp Elapsed Client Action/Code Size Method URI Ident Hierarchy/
From Content
According to Squid 2.0 documentation [squid], these fields are
defined as follows:
+-----------+-------------------------------------------------------+
| Element | Definition |
+-----------+-------------------------------------------------------+
| time | Unix timestamp as UTC seconds with a millisecond |
| | resolution. |
| duration | The elapsed time in milliseconds the transaction |
| | busied the cache. |
| client | The client IP address. |
| address | |
| bytes | The size is the amount of data delivered to the |
| | client, including headers. |
| request | The request method to obtain an object. |
| method | |
| URL | The requested URL. |
| rfc931 | may contain the ident lookups for the requesting |
| | client (turned off by default) |
| hierarchy | The hierarchy information provides information on how |
| code | the request was handled (forwarding it to another |
| | cache, or requesting the content to the Origin |
| | Server). |
| type | The content type of the object as seen in the HTTP |
| | reply header. |
+-----------+-------------------------------------------------------+
Table 6: Information elements in Squid format
Squid also uses a "store log", which covers the objects currently
kept on disk or removed ones, for debugging purposes typically.
Appendix B. Requirements
B.1. Additional Requirements
Section 7 of [I-D.ietf-cdni-requirements], already specifies a set of
requirements for Logging (LOG-1 to LOG-16). Some security
requirements also affect Logging (e.g., SEC-4).
Bertrand, et al. Expires August 26, 2013 [Page 38]
Internet-Draft CDNI Logging February 2013
This section is a placeholder for requirements identified in the work
on logging, before they are proposed to the requirements draft
authors.
Logging data is sensitive as it provides the raw material for
producing bills etc. Therefore, the protocol delivering the Logging
data must be reliable to avoid information loss. In addition, the
protocol must scale to support the transport of large amounts of
Logging data.
CDNs need to trust Logging information, thus, they want to know:
o who issued the Logging (authentication), and
o if the Logging has been modified by a third party (integrity).
Logging also contains confidential data, and therefore, it should be
protected from eavesdropping.
All these needs translate into security requirements on both the
Logging data format and on the Logging protocol.
Finally, this protocol must comply with the requirements identified
in [I-D.ietf-cdni-requirements].
[Ed. note: cf. requirements draft: "SEC-4 [MED] The CDNI solution
should be able to ensure that the Downstream CDN cannot spoof a
transaction log attempting to appear as if it corresponds to a
request redirected by a given Upstream CDN when that request has not
been redirected by this Upstream CDN. This ensures non-repudiation
by the Upstream CDN of transaction logs generated by the Downstream
CDN for deliveries performed by the Downstream CDN on behalf of the
Upstream CDN."]
B.2. Compliancy with Requirements draft
This section checks that all the identified requirements in the
Requirements draft are fulfilled by this document.
[Ed. node: to be written later]
Appendix C. Analysis of candidate protocols for Logging Transport
This section will be expanded later with an analysis of alternative
candidate protocols for transport of CDNI Logging in non-real-time as
well as real-time.
Bertrand, et al. Expires August 26, 2013 [Page 39]
Internet-Draft CDNI Logging February 2013
C.1. Syslog
[Ed. node: to be written later]
C.2. XMPP
[Ed. node: to be written later]
C.3. SNMP
Authors' Addresses
Gilles Bertrand (editor)
France Telecom - Orange
38-40 rue du General Leclerc
Issy les Moulineaux, 92130
FR
Phone: +33 1 45 29 89 46
Email: gilles.bertrand@orange.com
Iuniana Oprescu (editor)
France Telecom - Orange
38-40 rue du General Leclerc
Issy les Moulineaux, 92130
FR
Phone: +33 6 89 06 92 72
Email: iuniana.oprescu@orange.com
Stephan Emile
France Telecom - Orange
2 avenue Pierre Marzin
Lannion F-22307
France
Email: emile.stephan@orange.com
Bertrand, et al. Expires August 26, 2013 [Page 40]
Internet-Draft CDNI Logging February 2013
Roy Peterkofsky
Skytide, Inc.
One Kaiser Plaza, Suite 785
Oakland CA 94612
USA
Phone: +01 510 250 4284
Email: roy@skytide.com
Francois Le Faucheur (editor)
Cisco Systems
Greenside, 400 Avenue de Roumanille
Sophia Antipolis 06410
FR
Phone: +33 4 97 23 26 19
Email: flefauch@cisco.com
Pawel Grochocki
Orange Polska
ul. Obrzezna 7
Warsaw 02-691
Poland
Email: pawel.grochocki@orange.com
Bertrand, et al. Expires August 26, 2013 [Page 41]