Content Delivery Networks Interconnection
|Document||Charter||Content Delivery Networks Interconnection WG (cdni) Snapshot|
|Title||Content Delivery Networks Interconnection|
|IESG||Responsible AD||Francesca Palombini|
|Charter edit AD||Francesca Palombini|
|Send notices to||(None)|
A Content Delivery Network (CDN) is an infrastructure of network elements operating at layer 4 through layer 7, arranged for the efficient distribution and delivery of digital content. Such content includes, but is not limited to, web pages and images delivered via HTTP, and streaming of continuous media delivered via HTTP, RTSP, RTMP, etc. CDNs typically provide services to multiple Content Service Providers (CSPs). CDNs provide numerous benefits: a shared platform for multi-service content delivery, reduced transmission costs for cacheable content, improved quality of experience for end users and increased robustness of delivery. For these reasons they are frequently used for large-scale content delivery. As a result of the significant growth in content delivered over IP networks, existing CDN providers are scaling up their infrastructure and many Network Service Providers and Enterprise Service Providers are deploying their own CDNs. Subject to the policy of the CSP, it is generally desirable that a given item of content can be delivered to an end user regardless of that end user's location or attachment network. This creates a need for interconnecting (previously) standalone CDNs so they can interoperate and collectively behave as a single delivery infrastructure. The goal of the CDNI Working Group is to allow the interconnection of separately administered CDNs in support of the end-to-end delivery of content from CSPs through multiple CDNs and ultimately to end users (via their respective User Agents). The CDNI WG aims at delivering a targeted, deployable solution in a short timeframe as needed by the industry. It is expected that the CDNI interfaces will be realized using existing IETF protocols for transport and message exchange, and using existing object notation grammars/languages for the definition of CDNI objects and semantics. In the event that protocol extensions or new protocols are deemed necessary by the WG, the WG will recharter. The working group will focus on the following items: - A "requirements" document. This document lists the requirements for the CDNI architecture and the CDNI interfaces. In particular, this document will focus on identifying a reasonable set of more urgent and important requirements that will be addressed in the initial set of CDNI protocols and solutions produced by the working group. This document will list the requirements stemming from the threat analysis and to be met by each of the CDNI interfaces. - A "framework" document providing a description of the different components of the CDNI architecture and how they interact with one another. This document will also include a "threat analysis" discussing the security concerns and threats, the trust model and privacy issues specific to CDNI. - A specification of the "CDNI Request Routing Redirection interface". This interface will allow an upstream CDN Request Routing system to obtain from the downstream CDN the information necessary to perform request redirection. It is actually a logical bundling of two separate but related interfaces: * Footprint & Capability Advertisement interface: Asynchronous operations to exchange routing information (e.g., the network footprint and capabilities served by a given CDN) that enables CDN selection for subsequent user requests; and * Request Routing Redirection interface: Synchronous operations to select a delivery CDN (surrogate) for a given user request. - A specification of the "CDNI Metadata interface". This interface will allow the CDNs to exchange content distribution metadata of inter-CDN scope. Content distribution metadata refers to the subset of content metadata that is relevant to the distribution of the content and therefore is to be processed by CDNs (for example, this may include information enabling: content acquisition, geo-blocking, enforcement of availability windows or access control). - A specification of the "CDNI Logging interface". This interface will allow CDN logging systems to exchange logging information associated with actions that are relevant across CDNs (such as content distribution, content delivery and content routing actions) for purposes of accounting, analytics, monitoring, etc. - A specification of the "CDNI Control interface". In particular, this interface will allow an upstream CDN to remove or invalidate content in a downstream CDN. - A specification for "CDNI URI Signing". This document will specify a mechanism that allows interconnected CDNs to support access control by signing content URIs. This may involve extensions to the CDNI interfaces (e.g. CDNI Metadata interface, CDNI Logging interface). The WG will discuss and address the security, management and operational issues specific to CDNI, inside the above documents and specifications. The working group will only define solutions for aspects of the CDN Interconnection problem space that require direct communication or interoperation between CDNs. In particular, the WG will not define: - New session, transport or network protocols. - New protocols for delivering content from a CDN to an End User/User Agent. - New protocols for ingestion of content or metadata between a CSP and a CDN. - New protocols for acquiring content across CDNs. - Protocols and algorithms for intra-CDN operations. - Support for Transparent Caching across CDNs. - New applications consuming CDNI logs. - Digital Right Management (DRM) mechanisms. The CDNI WG will work with other IETF WGs to assess, and where appropriate, leverage protocols developed by those WGs, in order to realize the CDNI requirements and CDNI interfaces. For example, the WG may assess the suitability of the ALTO protocol as a protocol to enable downstream CDNs to exchange information which may aid an upstream CDN with making CDNI request routing decisions. The CDNI WG will also coordinate with relevant groups outside the IETF, if and where appropriate.