How do you compare and contrast TCP/IP state transition diagram with other transport layer protocols?

This is very helpful in understanding TCP/IP. Since IP is mentioned as a Layer 3 protocol, would it be good to add that TCP (and for that matter UDP) sit at the Layer 4 Transport layer? Also, what specific action changes the state transition diagram from CLOSED to LISTEN? Is it a client request to a server? Thanks! Pat

IP protocol is a Layer 3 (OSI Model) protocol that routes a data packet across internet from source to a destination computer, but does not guarantee delivery of packets. The session management functionality is provided by TCP protocol, which is de facto protocol used by applications for reliable data transfer. TCP runs on top of IP protocol. TCP state machine provides orderly connection initiation, establishment, keep alive, termination , preserves the data sequence and no data loss (reliable delivery) for applications. Another feature of TCP is, it very well adopts to fluctuating network conditions - poor reliability, varying bandwidth, etc. All these makes TCP state machine more complex.

TCP state transition is pretty sophisticated. As some large service provider found out and adapted a technique to close the connection instead of going through all the states ( FIN1, FIN2 etc. ), just simply generate the reset (RST) message. This was there all the time, to enable TCP from recovering from dead peers, but nothing prevents it from being used from closing connections and save lot of bandwidth especially when done at huge volumes.

The User Datagram Protocol (UDP) differs from TCP in that it does not provide reliability, ordering, or error-checking. Unlike TCP, which uses a state transition diagram to manage connections, UDP is connectionless, meaning it does not establish, maintain, or terminate connections. UDP simply sends and receives datagrams with a source and destination address. As such, UDP has no state transitions. It is ideal for applications needing fast, efficient data transmission that can tolerate some data loss or disorder, such as video streaming, VoIP, or online gaming. From my experience, UDP's simplicity and speed make it a go-to for these scenarios.

Comparing and contrasting TCP/IP's state transition diagram with UDP and SCTP: - Reliability and Ordering: TCP ensures reliability through mechanisms like acknowledgment, and flow control, which are reflected in its state transitions. UDP lacks these mechanisms, making it unreliable and unordered. - Connection Establishment and Termination: TCP and SCTP are connection-oriented protocols and UDP, being connectionless. - Complexity and Flexibility: TCP's state transition diagram is well-defined and widely understood due to TCP's ubiquity. SCTP's state transition diagram is more complex due to its support for multiple streams within a single connection. UDP's simplicity, by contrast, leads to its lack of a state transition diagram.

An actual state diagram, or at the very least, a verbal description of state transitions, would be helpful for this article - admittedly, these exist all over the net.