1. Scale & Traffic Characteristics
Netflix accounts for a massive percentage of peak global downstream traffic. Rather than relying solely on commercial CDNs like Akamai or CloudFront, Netflix built its own custom CDN called Open Connect.
Open Connect Appliances (OCAs)—custom FreeBSD storage servers with high-speed 100GbE NICs—are embedded directly inside thousands of Internet Service Provider (ISP) networks around the globe. This brings 95%+ of video bytes within single-hop distance of subscribers.
2. Control Plane (AWS) vs Data Plane (Open Connect)
Netflix bifurcates its architecture into two distinct domains: The Control Plane (running in AWS across multiple regions) and the Data Plane (Open Connect OCAs).
The AWS tier manages user signup, billing, catalog browsing, and recommendation generation. The OCA network handles all heavy video byte delivery. Even if AWS suffers a control plane disruption, users with active playback sessions continue streaming uninterrupted from local OCAs.
3. Per-Title & Per-Shot Dynamic Video Encoding
Traditional video pipelines encoded all titles at static bitrates (e.g. 1080p at 5Mbps). Netflix pioneered shot-based encoding: an animated cartoon scene requires far fewer bits than high-action sports with rapid camera pans.
By analyzing complexity at the individual shot level, video quality is maximized while reducing overall bandwidth consumption by 20-30%.
4. Personalized Recommendation System
The recommendation engine combines collaborative filtering, deep reinforcement learning, and contextual bandits. Candidate generation narrows down millions of titles to a few hundred candidates, which a neural ranking model scores according to viewing history, device type, and time of day.
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Written by HLDForge Architecture Team
Staff Media Systems Architect
The HLDForge Architecture Team publishes practical engineering guides, real-world case studies, and high-concurrency blueprints to help engineers build scalable and fault-tolerant software.