Subject: [CDNi] I-D Action: draft-ietf-cdni-use-cases-00.txt

From: [email-masked]
Date: Thu, 22 Sep 2011 12:36:39 -0700

A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Content Delivery Networks Interconnection Working Group of the IETF.

	Title           : Use Cases for Content Delivery Network Interconnection
	Author(s)       : Gilles Bertrand
                          Stephan Emile
                          Grant Watson
                          Trevor Burbridge
                          Philip Eardley
                          Kevin Ma
	Filename        : draft-ietf-cdni-use-cases-00.txt
	Pages           : 17
	Date            : 2011-09-22

   Content Delivery Networks (CDNs) are commonly used for improving the
   footprint and the end-user experience of a content delivery service,
   at a reasonable cost.  This document outlines real world use-cases
   (not technical solutions) for interconnecting CDNs.  It can be used
   to provide guidance to the CDNI WG about the interconnection
   arrangements to be supported and to validate the requirements of the
   various CDNI interfaces.

   This document describes a number of use cases that motivate CDN
   Interconnection.  It represents a work in progress and may be
   extended later to cover additional use-cases.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-cdni-use-cases-00.txt

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

This Internet-Draft can be retrieved at:
ftp://ftp.ietf.org/internet-drafts/draft-ietf-cdni-use-cases-00.txt

---

From: Scott Wainner <[email-masked]>
Date: Thu, 29 Sep 2011 20:02:04 -0400

Section 2.3 Nomadic Users
   This description falls under the category of Geographic Extension yet 
the third paragraph states the case where a different device is used in 
the same CDN coverage area.  The intent of this use case needs to be 
clarified.  Perhaps the use case is trying to address the scenario where 
a Nomadic User-A with an agreement allowing access to content from CSP-A 
via uCDN moves to a dCDN in a different region.  The dCDN is allowed to 
distribute the content of CSP-A to User-A; however, not other users in 
the region of the dCDN are allowed to retrieve the content unless they 
too have such an agreement.

Section 5.1.3 Content Encoding Restrictions
   Need to clarify if we're talking about the restrictions on the 
delivery of specific content or the restrictions on the ability of a CDN 
to deliver specific content.  I certainly understand the case where a 
CSP will restrict the distribution of content to a "managed path" if 
such content is HD while allowing the content distribution via an 
un-managed path if such content is SD (same could apply to encryption 
methods, delivery methods, etc.).  On the contrary, the dCDN may have 
its own restrictions of blocking the distribution of HD content while 
allowing the distribution of SD content.

   o first bullet makes sense if the dCDN can perform a subset of 
encapsulations for a reference set of media (e.g. HLS, HSS, but not DASH)
   o second bullet makes sense where the dCDN doesn't want to offer high 
bit-rate variants of the media
   o third bullet make sense if the policy addresses QoE but I don't 
think subscriber rights/authorizations apply.

Section 10 Security Considerations

Aside from the security considerations WITHIN the uCDN and dCDN, I think 
we can describe this in four contexts:

a. The relationship between the CSP and the uCDN (the principle contract 
arrangement for distribution)
b. The relationship between the uCDN and dCDN (the transitive trust 
relationship that extends the contract defined in (a) above)
c. The relationship between the User and dCDN (the recognition of right 
to download predicated on (b) above)
d. The relationship between the User and CSP (the contract authorizing 
the user access to the content)

The user is not interested in the a-b nor the b-c relationship. The user 
is only interested in the transparency and interoperability of the 
security relationship between d-b or d-c to the point that the 
authorization granted in d-a is viable when the delivery is initiated 
via either d-b or d-c.  As an example, the uCDN might use URL appended 
tokens for authentication while dCDN might use URL appended hashes.  The 
user doesn't want to know about the distinct methods, but transparency 
is only afforded if the methods are interoperable clearly defined when 
the delegation for content delivery is executed.  Clearly, the choice of 
authentication method is determined by the respective CDN's.

Scott

---

From: Kevin J Ma <[email-masked]>
Date: Fri, 30 Sep 2011 10:45:13 -0400

Hi Scott,

  We are currently updating section 2.3.  I think the nomadic use case
  includes not only geographic extension, but more generically footprint
  extension.  A carrier CDN with only an in-network presense for specific
  devices (e.g., mobile vs TV) may want to increase its device footprint
  by interconnecting with another local carrier CDN that supports other
  devices or subscribers.  We are also looking at removing section 5.1.3.

  > As an example, the uCDN might use URL appended
  > tokens for authentication while dCDN might use URL appended hashes.
  ...
  > Clearly, the choice of

  Content providers typically implement apps today with an understanding that
  the uCDN has a specific authentication method.  If the uCDN delegates
  delivery to a dCDN that the content provider has no relationship with, the
  app may have no ability to switch authentication methods.  Would the uCDN be
  responsible for generating of the proper dCDN credentials for the user?

thanx.

--  Kevin J. Ma

> -----Original Message-----
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> Scott Wainner
> Sent: Thursday, September 29, 2011 8:02 PM
> To: [email-masked]
> Subject: Re: [CDNi] I-D Action: draft-ietf-cdni-use-cases-00.txt
> 
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