Connection Establishment & Flow and Congestion Control

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1. Connection Establishment & Flow and Congestion Control

2. For More Slides Visit https:// www.slideshare.net/adeel02 https://chauhantricks.blogspot.com/ Adeel Rasheed

3. Connection Establishment A connection is a requirement of a reliable data delivery service. It is set up before the actual data exchange takes place . The connection is used to acknowledge the receipt of packets and retransmit those that are lost.

4. Requirement Required by connection-oriented transport protocols like TCP N eed connection establishment procedures to allow: each end to know the other exists negotiation of optional parameters triggers allocation of transport entity resources

5. Ways of Establish the connection Two-Way Handshake Three-Way Handshake

6. Three-Way Handshake SYN+ACK

7. SYN: It is for synchronization of sequence numbers It consumes 1 sequence number Carries no real data SYN+ACK : SYN segment for communication in other direction and ACK for the received SYN It consumes 1 sequence number ACK Just an ACK segment Does not consume any sequence number

8. three way handshake SYN, SYN-ACK, ACK connection determined by source and destination sockets (host, port) can only have a single connection between any unique pairs of ports but one port can connect to multiple ports

9. Flow Control Flow control is the mechanism that ensures the rate at which a sender is transmitting is in proportion with the receiver’s receiving capabilities.

10. Flow Control Method Stop-and-wait Sliding-window

11. Stop-and-wait This is the simplest form of flow control where a sender transmits a data frame. After receiving the frame, the receiver indicates its willingness to accept another frame by sending back an ACK frame acknowledging the frame just received.

12. Sliding-window With the use of multiple frames for a single message, the stop-and-wait protocol does not perform well. Only one frame at a time can be in transit. In stop-and-wait flow control, if a > 1 , serious inefficiencies result.

13. Sender sliding Window : Receiver sliding Window:

14. Congestion Control Congestion is a situation in Communication Networks in which too many packets are present in a part of the subnet, performance degrades. Congestion in a network may occur when the load on the network  (i.e.  the number of packets sent to the network) is greater than the capacity of the network  (i.e.  the number of packets a network can handle.). Network congestion occurs in case of traffic overloading.

15. Causes Of Congestion if all of a sudden a stream of packets arrive on several input lines and need to be out on the same output line. Slow processors also cause Congestion. If the router CPU is slow at performing the task.

16. Effects of Congestion Congestion affects two vital parameters of the network performance 1. Through put 2. Delay

17. Congestion Control Techniques Open loop: Protocols to prevent or avoid congestion, ensuring that the system never enters a Congested State. Close loop: Protocols that allow system to enter congested state, detect it, and remove it.

18. Congestion Control Algorithms Leaky Bucket Algorithm Token Bucket Algorithm