Congestion control is about controlling traffic entry into telecommunication networks, so as to avoid congestive collapse by attempting to avoid; or by detecting oversubscription of any of the processing or link capabilities of the intermediate nodes and networks and taking resource reducing steps, such as sending packets more slowly.

ATM

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For discussion of ATM network congestion control see Congestion control in ATM networks.

Internet Protocol

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The Internet protocols are designed to prevent and minimise congestion; in particular the TCP has congestion avoidance built in and should be used for nearly all protocols that can consume a lot of network resources. UDP has no congestion avoidance properties built in at all and protocols built on it can easily congest networks, unless they are extremely carefully designed.

The algorithms used for congestion control on the internet include:

End point algorithms

• Slow-start
• Exponential backoff
• sliding window
• fast retransmit
• fast recovery

Router algorithms

Random early detection