connection establishment flow and congestion control

2. Connection Establishment
⚫A connection is a requirementof a reliabledata
delivery service.
⚫It is set up before theactual dataexchange takes place.
⚫ The connection is used toacknowledge the receiptof
packets and retransmit those thatare lost.

3. Requirement
⚫Required byconnection-oriented transport protocols
like TCP
⚫Need connection establishment procedures toallow:
each end to know theotherexists
negotiation of optional parameters
triggers allocationof transportentity resources

4. Ways of Establish the connection
⚫Two-Way Handshake
⚫Three-Way Handshake

5. Three-Way Handshake
SYN+ACK

6. ⚫SYN:
⚫It is forsynchronization of sequence numbers
⚫It consumes 1 sequence number
⚫Carries no real data
⚫SYN+ACK:
⚫SYN segment forcommunication in otherdirection and
⚫ACK forthe received SYN
⚫It consumes 1 sequence number
⚫ACK
⚫Justan ACK segment
⚫Does not consume any sequence number

7. ⚫threeway handshake
SYN, SYN-ACK, ACK
⚫connection determined by sourceand destination
sockets (host, port)
⚫can only havea single connection between any unique
pairsof ports
⚫butone portcan connect to multipleports

8. Flow Control
⚫Flowcontrol is the mechanism thatensures thesender
how muchdatashould besenttoreceiver that it is not lost.
⚫this mechanism makes thesendertowait foran
acknowlegement before sending the nextdata.
⚫this technique thatallowstwostationsworking atdifferent
speeds tocommunicatewitheachother.
⚫flowcontrol alsoworksondata link layer.

9. Flow Control two
Methods
⚫Stop-and-wait
⚫Sliding-window

10. 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.

11. Sliding-window
⚫With the useof multiple frames fora single message,
the stop-and-wait protocol does not perform well.
⚫it allows to sender to send a specific number of
packets or frames before requiring a
acknowledgment from the receiver.
⚫it commonly used in protocols like TCP for reliable
data transmission over the internet.

12. ⚫Sendersliding Window:
⚫Receiversliding Window:

13. Congestion Control
⚫Congestion isa situation in Communication Networks
in which too many packets are present in a part of the
subnet, performance degrades. Congestion in a
network mayoccurwhen the load on the
network (i.e. the numberof packets sent to the
network) is greater than the capacity of the
network (i.e. the numberof packetsa network can
handle.). Networkcongestionoccurs in caseof traffic
overloading.

14. Causes Of Congestion
⚫if all of a sudden a stream of packets arrive on several
input linesand need to beouton the sameoutput line.
⚫Slowprocessorsalsocause Congestion. If the router
CPU is slowat performing the task.

15. Effects of Congestion
⚫Congestion affects twovital parameters of the network
performance
⚫1. Through put
⚫2. Delay

16. Congestion Control Techniques
⚫Open loop: Protocols topreventoravoid congestion,
ensuring that the system never enters a Congested
State.
⚫Close loop: Protocols thatallowsystem toenter
congested state, detect it, and remove it.

17. Congestion Control Algorithms
⚫Leaky BucketAlgorithm
⚫Token BucketAlgorithm