What is a Microburst?
A microburst is a sudden, massive spike in network traffic lasting microseconds to milliseconds. While average bandwidth might look acceptable, these instantaneous peaks can be 10-100x higher—overwhelming buffers and causing packet loss.
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Microburst Traffic Pattern
Green dashed line = Average bandwidth (40 Gbps) • Orange spike = Instantaneous burst (400 Gbps)
Traditional vs AI Traffic Patterns
Traditional web and enterprise traffic spreads smoothly across time. AI training traffic is fundamentally different—thousands of GPUs synchronize simultaneously, creating explosive bursts that shatter network assumptions.
🌐 Traditional Traffic
🤖 AI Training Traffic
GPU Gradient Synchronization
During AI training, GPUs compute independently, then must share results simultaneously. When 10,000+ GPUs all transmit at once, network fabric sees an instant traffic explosion.
🔄 Distributed Training: All-Reduce Synchronization
InfiniBand
Each GPU computes gradients → All GPUs transmit simultaneously → Network sees 16× parallel 400G flows
⏱️ Training Step Timeline
Why Microbursts Matter
When bursts overwhelm network buffers, packets are dropped. In AI training, dropped packets trigger retransmissions that delay ALL GPUs, creating a cascade of wasted compute cycles.
Buffer Overflow
Switch buffers fill in microseconds during bursts
Packet Loss
Even 0.1% loss degrades training by hours
GPU Idle Time
$10,000+ GPUs waiting for network
How One Burst Breaks Everything
A single microburst can trigger a cascade that stalls thousands of GPUs across multiple tenants—demonstrating why isolation at wire speed is non-negotiable.