CDNi

CDNi, or Content Delivery Network Interconnection, is an architectural framework and set of standardized interfaces that enables interconnection of independent CDNs. It allows a content provider or CDN operator to deliver content across multiple CDNs and to route end-user requests to the most suitable delivery network.

The framework is designed to support dynamic selection, policy enforcement, and coordinated delivery. It defines a reference architecture separating concerns across control, data, and management planes, and introduces mechanisms for discovering and negotiating capabilities, footprints, and service descriptions between interconnected CDNs.

Key interfaces include the CDNI Metadata interface (for capability and footprint exchange), the CDNI Request Routing interface (for directing user requests to an appropriate CDN), the CDNI Transfer interface (for provisioning and cache management of content), and the CDNI Logging interface (for sharing delivery and usage data for auditing and billing).

Standardization work is conducted by the IETF CDNi Working Group, which has produced a set of framework and protocol specifications known as RFCs. These documents describe requirements, reference architectures, and interface specifications to enable interoperable CDNI deployments.

Applications of CDNi include multi-CDN strategies, disaster recovery, and policy-compliant content delivery across administrative domains. Real-world deployment has been exploratory and varies by operator and use case, with ongoing development and refinement in standard bodies. See also content delivery networks, network interconnection, and IETF standards.