3.5. Congestion Control

In addition to dealing with the capacity of the recipient, TCP also must adapt the transfer rate because of congestion on the network. If TCP did not adapt to congestion, an overloaded network would result in dropped packets, which would cause retransmissions that would further increase the congestion, for a snowball effect. To address this problem, TCP reduces its transfer rate if it detects congestion, by increasing its transfer rate until packets are lost and then drastically reducing the transfer rate. Subsequently, TCP increases the transfer rate again in order to probe continually for the network's bottleneck bandwidth between the two end hosts of the connection.

TCP implements this functionality by maintaining a ...

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