TCP Sequence Diagrams

TCP 3-way handshake

The sequence diagrams presented here describe the 3-way handshake setup and release of a TCP connection. The byte level sequence numbers and TCP Ack handling is also shown.

TCP sequence diagram

This sequence diagram explores the three-way handshake, data transfer and TCP connection release. The diagram includes socket level details.

TCP connection overview

An overview of the TCP connection, data transfer and release.

TCP connection with focus on client

TCP connection setup and release with focus on the client

TCP connction with focus on server

TCP connection setup and release with focus on the server

TCP connection context diagram

A context diagram of entities involved in a TCP connection

TCP slow start

Analyse "Slow start" congestion control mechanisms built right into TCP. As the name suggests, "Slow Start" starts slowly, increasing its window size as it gains confidence about the network's throughput.

TCP slow start

Congestion control ensures that TCP does not pump data at a rate higher than what the network can handle.

TCP slow start overview

An overview of the TCP slow start.

TCP slow start with focus on client

Client view of the slow start procedure

TCP slow start with focus on server

A server side look at the slow start

TCP congestion avoidance

TCP connection starts up in slow start mode, geometrically increasing the congestion window (cwnd) until it crosses the slow start threshold (ssthresh). Once cwnd is greater that ssthresh, TCP enters the congestion avoidance mode of operation. In this mode, the primary objective is to maintain high throughput without causing congestion. If TCP detects segment loss, TCP reduces its data flow rate by reducing cwnd. After reducing cwnd, TCP goes back to slow start.

TCP congestion avoidance

Primary objective of congestion avoidance is to maintain high throughput without causing congestion.

TCP congestion overview

An overview of the TCP congestion avoidance.

TCP congestion avoidance with focus on client

Client view of the TCP congestion avoidance procedure.

TCP congestion avoidance with focus on server

A server side look at the TCP congestion avoidance.

TCP Fast Retransmit and Fast Recovery Sequence Diagram

Fast Retransmit and Recovery detect a segment loss via duplicate acknowledgements. When a segment is lost, TCP at the receiver will keep sending ack segments indicating the next expected sequence number. This triggers fast recovery at the transmitter.

TCP Sequence Diagrams

TCP 3-way handshake