A network protocol is a set of established rules that dictates how to format, transmit and receive data so computer network devices -- from servers and routers to endpoints -- can communicate regardless of the differences in their underlying infrastructures, designs or standards.
To successfully send and receive information, devices on both sides of a communication exchange must accept and follow protocol conventions. Support for network protocols can be built into software, hardware or both.
Standardized network protocols provide a common language for network devices. Without them, computers wouldn't know how to engage with each other. As a result, except for specialty networks built around a specific architecture, few networks would be able to function, and the internet as we know it wouldn't exist. Virtually all network end users rely on network protocols for connectivity.
How protocols work
Network protocols break larger processes into discrete, narrowly defined functions and tasks across every level of the network. In the standard model known as Open Systems Interconnection (OSI), one or more network protocols govern activities at each layer in the telecommunication exchange.
A set of cooperating network protocols is called a protocol suite. The TCP/IP suite includes numerous protocols across the data, network, transport and application layers, for example, working together to enable internet connectivity. These include:
- Transmission Control Protocol (TCP), which uses a set of rules to exchange messages with other internet points at the information packet level;
- Internet Protocol (IP), which uses a set of rules to send and receive messages at the internet address level; and
- additional network protocols that include the Hypertext Transfer Protocol (HTTP) and File Transfer Protocol (FTP), each of which has defined sets of rules to exchange and display information.
Network protocols are often set forth in an industry standard -- developed, defined and published by groups such as the International Telecommunication Union, the Institute of Electrical and Electronics Engineers, the Internet Engineering Task Force, the International Organization for Standardization and the World Wide Web Consortium.
Types of protocols
Falling into these three broad categories are thousands of network protocols that uniformly handle an extensive variety of defined tasks, including authentication, automation, correction, compression, error detection, file retrieval, file transfer, link aggregation, routing, semantics, synchronization and syntax.
Some network protocol examples include:
- Address Resolution Protocol
- Blocks Extensible Exchange Protocol
- Border Gateway Protocol
- Binary Synchronous Communications
- Canonical Text Services
- Domain name system
- Dynamic Host Configuration Protocol
- Enhanced Interior Gateway Routing Protocol
- HTTP over SSL
- Human interface device
- Internet Control Message Protocol
- Internet Message Access Protocol
- Media access control
- Network News Transfer Protocol
- Open Shortest Path First
- Post Office Protocol
- Secure Sockets Layer
- Simple Mail Transfer Protocol
- Terminal Network
- Transmission Control Protocol
- Transport Layer Security
- Universal Description, Discovery and Integration
- User Datagram Protocol
- Voice over IP