Network Protocol is a protocol that operates at the network layer (layer 3) of the Open Systems Interconnection (OSI) reference model for networking.
OSI model is the most popular model used to establish open communication between two systems. To learn more about the OSI Model read the main article about this topic.
How network protocols work
Network protocols break larger processes into discrete, narrowly defined functions and tasks across every level of the network.
Network protocols are typically created according to industry-standard by various networking or information technology organizations.
The following groups are constantly publishing different network protocols:
- The Institute of Electrical and Electronics Engineers (IEEE)
- The Internet Engineering Task Force (IETF)
- The International Organization for Standardization (ISO)
- The International Telecommunications Union (ITU)
- The World Wide Web Consortium (W3C)
Most common network protocols
- TCP (Transmission Control Protocol): The TCP is able to transfer a continuous stream of octets in each direction between its users by packaging some number of octets into segments for transmission through the internet system. In general, the TCPs decide when to block and forward data at their own convenience. (IETF RFC793)
- IP (Internet Protocol): Based on the ARPA Internet Protocol, this protocol is designed for use in interconnected systems of packet-switched computer communication networks. The internet protocol provides for transmitting blocks of data called datagrams from sources to destinations, where sources and destinations are hosts identified by fixed length addresses. The internet protocol also provides for fragmentation and reassembly of long datagrams, if necessary, for transmission through “small packet” networks. (IETF RFC791)
- UDP (User Datagram Protocol): provides a procedure for application programs to send messages to other programs with a minimum of protocol mechanism. This protocol is transaction-oriented, and delivery and duplicate protection are not guaranteed. (IETF RFC768)
- POP (Post Office Protocol): The Post Office Protocol – Version 3 (POP3) is intended to permit a workstation to dynamically access a maildrop on a server host in a useful fashion. Usually, this means that the POP3 protocol is used to allow a workstation to retrieve mail that the server is holding for it. (IETF RFC1939)
- SMTP (Simple mail transport Protocol): The objective of the Simple Mail Transfer Protocol (SMTP) is to transfer mail reliably and efficiently. SMTP is independent of the particular transmission subsystem and requires only a reliable ordered data stream channel. While this document specifically discusses transport over TCP, other transports are possible. (IETF RFC5321)
- FTP (File Transfer Protocol): FTP provides a user-level oriented protocol for file transfer between host computers. (RFC 959)
- HTTP (HyperText Transfer Protocol): HTTP is an application-level protocol for distributed, collaborative, hypermedia information systems. It is a generic, stateless, protocol which can be used for many tasks beyond its use for hypertext, such as name servers and distributed object management systems, through the extension of its request methods, error codes, and headers. (RFC 2616)
- ICMP (Internet Control Message Protocol): ICMP, uses the basic support of IP as if it were a higher-level protocol, however, ICMP is actually an integral part of IP, and must be implemented by every IP module. (RFC 792)
Network protocols do not simply define how devices and processes work; they define how devices and processes work together. Without these predetermined conventions and rules, the internet would lack the necessary infrastructure it needs to be functional. Network protocols are the foundation of modern communications, without which the digital world could not stand.