Design Discord Voice System Design Interview

1. Problem Statement

2. Architecture Discussion Map

Use this as one discussion aid, not a single correct answer. Your design should follow from the requirements, scale, and trade-offs you establish.

graph TD
    A[Discord Client] -->|WebSocket Keep-Alive| B(WebSocket Gateway Cluster)
    B --> C[Presence Service]
    C --> D[(Redis: User Status)]
    B -->|Publish Event| E[Kafka Message Bus]
    E -->|Route to Consumers| B
    E -->|Persist| F[(Cassandra: Message History)]

3. Key Focus Areas

• 1
  Transport Protocol (UDP vs TCP)
• 2
  Media Server (SFU vs MCU)
• 3
  Jitter Buffers
• 4
  Geographic Routing
• 5
  Voice Activity Detection (VAD)