Content Delivery Network Interconnection (CDNI) Metadata

Approval announcement
Draft of message to be sent after approval:

From: The IESG <>
To: "IETF-Announce" <>
Cc:,, "The IESG" <>,,,,
Subject: Protocol Action: 'CDN Interconnection Metadata' to Proposed Standard (draft-ietf-cdni-metadata-21.txt)

The IESG has approved the following document:
- 'CDN Interconnection Metadata'
  (draft-ietf-cdni-metadata-21.txt) as Proposed Standard

This document is the product of the Content Delivery Networks
Interconnection Working Group.

The IESG contact persons are Alexey Melnikov, Ben Campbell and Alissa

A URL of this Internet Draft is:

Technical Summary

 This document defines a protocol by which a downstream CDN (dCDN) may
 query an upstream CDN (uCDN), in a CDN Interconnection (CDNI),
 to retrieve metadata related to a specific content asset being
 delivered by the dCDN, on behalf of the uCDN.  The metadata
 provides basic content delivery information, e.g., how to acquire
 the content asset, as well as optional content delivery policy
 information, e.g., geographic, time, and delegation restrictions.

Working Group Summary

 The metadata is organized hierarchically, starting with the host
 and further differentiated by URI path of the content.
 There was a lot of discussion early on as to whether a generic
 metadata interface was feasible or needed; there was concern
 that the complexity of designing a generic metadata interface
 would be prohibitive. 

 Much effort was put into defining how the metadata should be organized,
 so as to allow inheritance and override within the hierarchy, as well
 as metadata object reuse between hierarchies. There was broad discussion
 in the WG on this topic.  There were requirements for being able
 to exchange core pieces of metadata (e.g., how to acquire content),
 but there was also a desire to create an extensible protocol.
 Multiple drafts were submitted and merged to arrive at the final design.
 In addition to the extensible structure of the metadata, much discussion
 and effort was put into making sure that transit CDNs, which may or may
 not understand how to enforce the metadata, are able to safely
 redistribute the metadata or are able to recognize when redistribution
 of the metadata may violate content delivery policies.
 The focus of the document is on providing metadata for delivering content
 via HTTP.  While the same metadata can be used to deliver content via HTTPS,
 there is no metadata defined for conveying metadata specific to setting up
 TLS connections between the dCDN and the end user.  It was discussed within
 the WG, but a secure solution was not deemed within the expertise of the WG.
 Other solutions (e.g., LURK) could be used to address the TLS connection
 setup problem, and a CDNI metadata extension could be added once such
 a solution is available.

Document Quality

 The document was well reviewed in the WG.
 AppsDir review was performed by Matt Miller.


 The document shepherd is Francois Le Faucheur. The responsible
 AD is Alexey Melnikov.