Traditional TCP Congestion Control (CUBIC) interprets 'Packet Loss' as 'Congestion'. Why is this a problem on modern high-speed networks?
- A CUBIC tends to interpret random noise or signal interference on high-speed wireless networks as congestion, and its loss-based logic can lead to massive 'Bufferbloat' delays.
- B Statistical analysis of modern high-speed infrastructure shows that physical packet loss has become mathematically impossible, rendering CUBIC's primary feedback mechanism obsolete.
- C CUBIC is fundamentally too aggressive for modern fiber-optic links, often causing widespread network-level collapse by flooding intermediate switches with unproccessed data.
- D The implementation of the CUBIC algorithm is strictly limited to legacy IPv4 routing architectures and cannot be utilized on modern, 128-bit IPv6-only network segments.
Classic congestion control (like CUBIC) waits for a packet to be dropped before it slows down. On a 'long-fat network' (high bandwidth + high latency), the application can dump massive amounts of data into the routers' buffers before a drop actually happens. These full buffers cause 'Bufferbloat'—where your ping spikes to 500ms simply because the router's queue is full. Google's BBR (Bottleneck Bandwidth and RTT) is smarter: it probes the network to see how much it can *actually* handle without filling buffers, maintaining high throughput with much lower latency. This transition from 'reactive loss-based' to 'proactive model-based' control is a major leap in network efficiency.
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