Design and Analysis of TCP Connection States Using Finite Automata

Transmission Control Protocol (TCP) is a fundamental protocol in the Internet Protocol Suite, responsible for establishing reliable data transmission between devices in network communication. This study models TCP connection states using Non-Deterministic Finite Automata (NFA) and Pushdown Automata (PDA), specifically implementing the three-way hand- shake and data transfer processes through these formal methods. Each TCP state, from connection initiation to termination, is represented by corresponding automata states, demonstrating the applicability of Formal Language Automata (FLA) in illustrating TCP's state-driven structure. A side-by-side comparison of NFA and PDA, showing important distinctions in how each handles the complex flow of TCP—NFA provides the simplest solution because it is stateless. Still, the stack-based memory of PDA is better suited for the layered nature of TCP, where there are states for connection setup, data transfer, and connection teardown that can nest and recurse is provided. PDA, therefore, better meets these requirements for accurately capturing layered and memory- dependent processes of TCP communication.