Network protocol

A network protocol is a set of formal rules and standards that define how data is formatted, sent, and received between devices in a computer network. These protocols are essential because they allow different types of devices and software, even from different manufacturers, to communicate consistently and understandably.

Protocols act like a common language and etiquette for network communication. They govern the entire process of exchanging information, from how a connection is made to how errors are handled and how a communication session ends.

Overview and Purpose

Without network protocols, devices wouldn't know how to interpret the signals they receive or how to structure the data they send. Protocols provide the necessary guidelines for all communication aspects, ensuring interoperability between diverse systems.

The main purpose of network protocols is to enable reliable, efficient, and standardized communication across networks. They hide the complex details of the underlying hardware, letting software developers and users focus on sending and receiving data without needing to understand intricate low-level transmission details.

What Protocols Define

Network protocols specify various aspects of the communication process, including:

Data Format

Protocols define how data should be structured into packets, frames, or messages for transmission. This includes header information (like source/destination addresses, length, sequence numbers) and the actual data (payload).

Timing

Protocols determine when and how data can be sent, including rates (e.g., bits per second), sequencing (the order packets should be sent and processed), and flow control (managing data transfer speed to prevent overwhelming the receiver).

Error Handling

Protocols include ways to detect errors during transmission (e.g., using checksums) and often methods to request retransmission of lost or corrupted data to ensure reliability.

Addressing

Protocols define how devices on the network are identified and located, allowing data packets to be sent to the correct destination (e.g., using IP addresses or MAC addresses).

Connection Management

Protocols specify how communication sessions are established between devices (e.g., the three-way handshake in TCP) and how they are terminated.

Protocol Stacks and Layers

Network protocols are often organized into protocol stacks or layers. Each layer handles a specific part of the communication and provides services to the layer above it while using the services of the layer below it. This modular approach simplifies design and allows different protocols at different layers to be swapped. The most widely used example is the TCP/IP suite (often simplified to 4 or 5 layers), which forms the basis of the Internet.

Examples of Network Protocols

Many network protocols exist, each for specific purposes or operating at different layers of the network stack. Some common examples include:

• IP (Internet Protocol): Handles addressing and routing packets across networks.
• TCP (Transmission Control Protocol): Provides reliable, connection-oriented data transfer between applications, ensuring data arrives correctly and in order.
• UDP (User Datagram Protocol): Provides faster, connectionless data transfer with less overhead than TCP, but without guaranteed delivery; suitable for real-time applications like streaming or online gaming.
• HTTP / HTTPS (Hypertext Transfer Protocol / Secure HTTP): Used for transferring files (like web pages) on the World Wide Web. HTTPS adds encryption for security.
• FTP (File Transfer Protocol) / SFTP (SSH File Transfer Protocol): For transferring files between computers. SFTP adds security over SSH.
• SSH (Secure Shell): For secure remote login and command-line execution.
• DNS (Domain Name System): Translates human-readable domain names (like `google.com`) into IP addresses that computers use.

Importance

Network protocols are fundamental to how computer networks and the Internet work. They ensure that devices and software from different vendors can communicate effectively, enabling the global connectivity and vast range of online services we use today. Following standardized protocols promotes open systems and fosters innovation.

See also

• TCP/IP
• OSI model