System designHardsd-g695

Subject Video conferencing sfu networkingLevel Senior–Staff~50 minCommon in Networking & APIs interviewsIndustries Technology, Telecom

Question

Design the media-routing backend for a group video-conferencing product (think 50-person calls, 5,000 concurrent meetings). Clients use WebRTC. You need <200 ms glass-to-glass latency, graceful degradation on bad networks, and the ability to scale a single large meeting beyond one server. Decide the topology (mesh vs. MCU vs. SFU), how you handle heterogeneous client bandwidth, and where the hard limits are.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.