Congestion control policies

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Congestion control policies are essential for managing data flow in computer networks to prevent congestion, which can lead to delays and data loss. These policies can be broadly classified into two categories: Open Loop and Closed Loop congestion control.

Open Loop Congestion Control

These policies aim to prevent congestion before it happens. Some common techniques include:

  • Retransmission Policy: Ensures packets are retransmitted only when necessary to avoid increasing congestion.
  • Window Policy: Uses selective repeat windows to resend only specific lost packets, reducing unnecessary retransmissions.
  • Discarding Policy: Routers discard less critical packets to maintain overall network quality.
  • Acknowledgment Policy: Reduces the number of acknowledgments sent to minimize network load.
  • Admission Policy: Checks resource requirements before establishing new connections to prevent congestion.

Closed Loop Congestion Control

These techniques address congestion after it has occurred. Some methods include:

  • Backpressure: A congested node stops receiving packets from upstream nodes, causing them to slow down or stop sending data.
  • Choke Packet: A congested node sends a choke packet to the source to reduce the rate of data transmission.
  • Implicit Signaling: The source detects congestion through increased delays or packet loss and adjusts its transmission rate accordingly.
  • Explicit Signaling: Network nodes explicitly notify the source about congestion, prompting it to reduce its transmission rate.

TCP Congestion Control

TCP uses specific algorithms to manage congestion, such as:

  • Slow Start: Gradually increases the transmission rate until congestion is detected.
  • Congestion Avoidance: Adjusts the transmission rate based on network conditions to avoid congestion.
  • Fast Retransmit and Fast Recovery: Quickly retransmits lost packets and recovers from congestion without reducing the transmission rate too drastically.

These policies and techniques help maintain network stability, reduce latency and packet loss, enhance throughput, and ensure fair resource allocation.

If you have any specific questions or need more details on any of these techniques, feel free to ask!

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