Building Express Backbone: Facebook’s new long-haul network

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Introduced the Express Backbone (EBB), a new long-haul network designed to separate cross-data center traffic from internet-facing traffic. EBB employs a hybrid traffic engineering model combining distributed control agents (Open/R) with a central controller. Key components include a BGP-based route injector, sFlow collector for traffic matrix estimation, a traffic engineering controller for path computation, Open/R agents for IGP and messaging, and LSP agents for programming forwarding tables. The design draws inspiration from data center network fabrics, using four parallel topologies ('planes') for incremental deployment and A/B testing. The controller's path allocation algorithm can optimize for latency, congestion, or scheduling priorities. Segment routing is used for simplified programming and improved robustness.