The concept of a Federated Cloud comprised of interconnected Service Providers (SP) was introduced in ATIS Standard ATIS-0200003, CDN Interconnection Use Case Specifications and High Level Requirements [https://global.ihs.com/doc_detail.cfm?&csf=ASA&input_doc_number=%20&inpu.... This initial standard described the role of the SPs in the cloud as distributors of content from Content Providers (CP) to End Users (EU). Thus, SPs serve as Content Distribution Network (CDN) Providers. The set of content delivery Life Cycle interactions between two CDN Providers is defined in ATIS-0200003. The method for content distribution in ATIS-0200003 was limited to Unicast Cache-based distribution.
Under certain conditions depending on network configurations and type of content, it may be advantageous to distribute content via Multicast methods. From a network perspective, Multicast is scalable and results in significant savings in efficiencies and capacity utilization.
The purpose of this ATIS Standard is to introduce Multicast-based content distribution. This standard provides the following:

• Overview of the Multicast delivery mechanism
• Set of content types that are suitable for delivery via Multicast methods
• Description of various Multicast methods that can be deployed to interconnect two CDN Providers and distribute content.

The scope of this Standard is limited to use cases and requirements to support the interactions between two CDN Providers for content distribution via Multicast. The Use Cases describe:

1. Generic interactions supporting Life Cycle Multicast use between two CDN Providers.
2. Specific Multicast configurations/scenarios that can be deployed for interconnection and content distribution.

Multicast related specifics to support Billing, Provisioning, Reporting, and other network functions will be covered in future ATIS documents. Multicast-based content delivery to mobility-based End User devices is for further study.