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Congestion control algorithms.pptx

  1. Submitted By Ujjwal matoliya Assignment computer network What is congestion? Traffic Shaping Congestion control algorithms Choke Packet
  2. Content What is congestion? Traffic Shaping Congestion control algorithms Choke Packet
  3. What is congestion? A state occurring in network layer when the message traffic is so heavy that it slows down network response time. Effects of Congestion As delay increases, performance decreases. If delay increases, retransmission occurs, making situation worse.
  4. Traffic Shaping A network traffic management technique. Traffic shaping is used to control bandwidth of the network to ensure quality of service to business-critical applications This technique uses parameters to shape the flow of network traffic : I. Average bandwidth II. Peak bandwidth
  5. Average Bandwidth : It is configured to set permitted bits per second across a port group level or a virtual/distributed virtual switch, over time. The rate of data transfer is permitted over time. Peak bandwidth : It decides maximum number of bits per second permitted across a port group level or a virtual/distributed virtual switch without discarding or queuing the frames.
  6. Time Data rate Average Bandwidth Peak bandwidth
  7. Congestion control algorithms 1.Leaky Bucket Algorithm 2.Token bucket Algorithm
  8. Imagine a bucket with a small hole in the bottom.No matter at what rate water enters the bucket, the outflow is at constant rate.When the bucket is full with water additional water entering spills over the sides and is lost. Leaky Bucket Algorithm
  9. The leaky bucket algorithm enforces output pattern at the average rate, no matter how bursty the traffic is. So in order to deal with the bursty traffic we need a flexible algorithm so that the data is not lost. One such algorithm is token bucket algorithm. Token bucket Algorithm
  10. 0 2 10 mbps 0 1 5 mbps
  11. Formula: M * s = C + ρ * s where S – is time taken M – Maximum output rate ρ – Token arrival rate C – Capacity of the token bucket in byte
  12. Choke Packet A choke packet is used in network maintenance and quality management to inform a specific node or transmitter that its transmitted traffic is creating congestion over the network. This forces the node or transmitter to reduce its output rate. Choke packets are used for congestion and flow control over a network. The source node is addressed directly by the router, forcing it to decrease its sending rate .The source node acknowledges this by reducing the sending rate by some percentage.