Congestion control

Congestion control

1. CONGESTION CONTROL GROUP member TABASSUM HAIDARY ABU TAHERA CHOWDHORY M ow NOUSHAD HASAN JABIN

2. WELCOME To Our Presentation

3. Topic Congestion Control

4. What is Congestion? Too much traffic on subnet cause congestion. It occur when subnet is out of buffer. Congestion On route. Queue overflows Packets droped Network congested.

5. Facts that Cause Congestion? Insufficient memory. Slow Processor. Packet arrival rate. Low Bandwidth line also cause congestion. The main cause of congestion is bursty nature of traffic.

6. Congestion Control To prevent the congestion we need some several principles or rules. These are: Load Sheding Choke Packets Traffic Shapping Random Early Discard

7. Load shedding Simple method drop packets Concept from electric power generation. Buffer full router discard packets. throw away packets. depends on application for discarded.

8. Wine Policy Example: File transmission. Milk Policy Example: Live Streaming.

9. Choke Packets Congested router generate choke packets Transmit them Upon receiving sender reduce transmission rate

10. Choke Packets Choke Packet Source Congested Router

11. Choke Packets A D E F A A E E D D F

12. Explicit Congestion Notification Congested router mark packets Forward to destination Destination send Congestion Signal to Source Source slow down

13. Hop By Hop Choke Packets Choke packet effect all hops Reduce congestion instantly More effective than Choke Packets over long distance

14. Hop By Hop Choke Packets A D F E F E A D D A E F A E F D

15. Random Early Detection Doesn’t wait for queue to be completely fill up Maintain an Average length of queue Average length exceeds, discard few packets Lost packets works as choke packets Sender notice them and slow down

16. Traffic Shaping Regulating the average rate and burstiness Of a flow of data that enters the network. Two traffic shaping algorithm are- #1: Leaky Bucket #2: Token Bucket

17. Leaky Bucket Shapes bursty traffic into fixed-rate traffic by averaging the data rate . Drop the packet if the bucket is full. Does nothing when input is idle.

18. Leaky bucket implementation

19. Token bucket The token bucket allows bursty traffic at a regulated maximum rate. -bucket holds tokens. -to transmit a packet, the host must capture and destroy one token. -tokens are generated by a clock at a rate one token every  t sec.

20. Token bucket

21. Thank You Any Question?