networkprotocol

A network protocol is a formal set of rules that governs the transmission of data between devices across a network. Protocols define how data is formatted into messages, how those messages are sent and acknowledged, how errors are detected and corrected, how devices identify and address each other, and how sessions are established and terminated.

Network communication is organized into layers, commonly described by the OSI model or the TCP/IP model. Each layer provides services to the layer above and relies on the layer below. Protocols at different layers handle tasks such as physical signaling, data framing, routing, transport, and application-level communication. Data is encapsulated as it moves down the stack and decapsulated as it moves up.

Major transport protocols include TCP, which is connection-oriented and reliable, and UDP, which is connectionless and best-effort. Application-layer protocols handle specific tasks: HTTP and HTTPS for web traffic, FTP for file transfer, SMTP for email, DNS for name resolution, and SSH for secure remote access. Application protocols often run on top of transport protocols and define their own message syntax and commands.

Standards are published and maintained primarily as RFCs by the Internet Engineering Task Force and other bodies. Protocol development emphasizes interoperability, security, and scalability. Security mechanisms such as TLS/SSL provide confidentiality and integrity for many application protocols.

In practice, networks implement hundreds of protocols. Examples include IP for addressing and routing, TCP and UDP for transport, ICMP for error reporting, ARP for link-layer address resolution, and BGP for interdomain routing. Understanding protocols is essential for configuring networks, diagnosing connectivity issues, and designing interoperable systems.