Congestion Control and Sharing a Link
In a loss-based congestion-control model, a sender probes for available capacity by raising its rate while packets arrive, then backs off when congestion signals appear. The rule helps senders share a link, while loss remains a signal rather than proof of one cause.
What a learner can do afterwards
- Explain why a sender treats a loss as a congestion signal in this model
- Describe how the sending rate rises and falls when the rule repeats
- Say what happens if one sender ignores backoff while others share the link
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In a loss-based congestion-control model, a sender cannot see unused capacity directly. It probes by raising its sending rate while acknowledgements arrive. A loss is treated as a sign that the path may be congested, so the sender backs off. Loss can have other causes, but this model uses it as a congestion signal.
The classic additive-increase, multiplicative-decrease pattern makes a sawtooth. The rate grows by small steps while traffic gets through. On a congestion signal, it drops by a larger fraction, then grows again.
A shared queue has limited space. If one sender never backs off, it can occupy more of the queue. Other senders lose room, delays rise, and losses can spread. The link has not gained capacity.
The sender probes with small increases, cuts back after a congestion signal, and shares queue space with other senders.
Original instructional content authored for os-taxonomy.
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