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 Cooper. A URL of this Internet Draft is: https://datatracker.ietf.org/doc/draft-ietf-cdni-metadata/ 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. Personnel The document shepherd is Francois Le Faucheur. The responsible AD is Alexey Melnikov.
