The Blockcast CDN

The Blockcast CDN is designed to address the growing demand for bandwidth in today’s internet.

Using home caching and multicast technology, Blockcast incentivizes the creation of more efficient content delivery infrastructure inside ISP networks, reducing capacity peaks and ensuring high-quality streaming for users, even during periods of high demand​.

What is the Blockcast CDN, and How is It Different?

Traditional CDNs in data centers and public networks face bandwidth and scalability constraints as millions of users demand higher-quality online streaming. The Blockcast CDN differs by leveraging home caching and multicast delivery that can be deployed in private ISP networks:

• Home Caching: Stores content closer to users, reducing the need for duplicated data streams over ISP transit to distant CDN servers. This lowers bandwidth usage and speeds up delivery times.

• Multicast Delivery: Instead of sending individual streams to each CDN node and end user, Blockcast uses shared streams to reach multiple destinations with a single resource. This reduces the number of duplicate streams and decreases network congestion.

This combination allows Blockcast to serve more users with fewer resources, ensuring better performance and lower costs, especially for high-demand content like live sports or 4K/8K streaming.

What is Multicast, and What Are Its Benefits?

Multicast is a content delivery method that sends a single stream of data to multiple users at once, unlike the traditional unicast model, which delivers an individual stream to each viewer.

Key Benefits of Multicast:

• Cost Reduction: By reducing the number of redundant streams, multicast can lower delivery costs by up to 10x, saving content providers significant resources​.

• Higher-Quality Streams: Multicast makes better use of available bandwidth, enabling users to enjoy high-bitrate content like 4K video without interruptions.

• Reduced Network Congestion: By sending fewer streams, multicast alleviates congestion, improving performance for ISPs and ensuring a smoother experience for viewers​.

Blockcast leverages multicast technology to offer a scalable, efficient solution to the growing bandwidth demands of today's internet.

TreeDN Architecture (RFC 9706)

Blockcast implements the TreeDN architecture defined in RFC 9706 — a tree-based CDN designed for live streaming to mass audiences. TreeDN combines Source-Specific Multicast (SSM) with Automatic Multicast Tunneling (AMT) overlays to deliver content efficiently across both multicast-enabled and unicast-only networks, enabling Replication-as-a-Service (RaaS) at a fraction of the cost of traditional CDNs.

The Blockcast TreeDN implementation consists of:

• CAST nodes as multicast content sources (ROUTE/FLUTE or MoQ-MMT)

• RELAY nodes as AMT relays and edge caches extending multicast coverage

• BEACON nodes as deep-edge receivers on modems, TVs, phones, and browsers

• DRIAD discovery (RFC 8777) for automatic nearest-relay selection

For a detailed technical walkthrough, see TreeDN: Multicast Content Delivery.

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