This article concerns communication between pairs of electronic devices. For the specific topic of computing protocols, see Protocol (computing). For protocols on two-way voice communications, see Voice procedure. For other meanings of the word protocol, see Protocol. In the field of telecommunications, a communications protocol is the set of standard rules for data representation, signalling, authentication and error detection required to send information over a communications channel. An example of a simple communications protocol adapted to voice communication is the case of a radio dispatcher talking to mobile stations. The communication protocols for digital computer network communication have many features intended to ensure reliable interchange of data over an imperfect communication channel. Communication protocol is basically following certain rules so that the system works properly. For other senses of this word, see protocol. ...
Voice procedure includes various techniques used to clarify, simplify and standardize spoken communications over two-way radios, in use by the military, in civil aviation, police and fire dispatching systems, citizens band radio (CB), etc. ...
Look up Protocol in Wiktionary, the free dictionary. ...
Telecommunication involves the transmission of signals over a distance for the purpose of communication. ...
A Communications channel (or channel for short), models the medium through which information is transmitted from a sender (or transmitter) to a receiver. ...
Network protocol design principles
Systems engineering principles have been applied to create a set of common network protocol design principles[citation needed]. These principles include effectiveness, reliability, and resiliency. Systems engineering techniques are used in complex projects: from spacecrafts to chip design, from robotics to creating large software products to building bridges, Systems engineering uses a host of tools that include modeling & simulation, requirements analysis, and scheduling to manage complexity Systems Engineering (SE) is an interdisciplinary approach and means...
Effectiveness A communications protocol needs to be specified in such a way that engineers, designers, and in some cases software developers can implement and/or use it. In human-machine systems, its design needs to facilitate routine usage by humans. Protocol layering accomplishes these objectives by dividing the protocol design into a number of smaller parts, each of which performs closely related sub-tasks, and interacts with other layers of the protocol only in a small number of well-defined ways. Look up engineer in Wiktionary, the free dictionary. ...
Systems design is the process or art of defining the hardware and software architecture, components, modules, interfaces, and data for a computer system to satisfy specified requirements. ...
A programmer or software developer is someone who programs computers, that is, one who writes computer software. ...
Human-machine system is a system in which the functions of a human operator (or a group of operators) and a machine are integrated. ...
Protocol layering allows the parts of a protocol to be designed and tested without a combinatorial explosion of cases, keeping each design relatively simple. The implementation of a sub-task on one layer can make assumptions about the behavior and services offered by the layers beneath it. Thus, layering enables a "mix-and-match" of protocols that permit familiar protocols to be adapted to unusual circumstances. In cryptanalysis, a brute force attack on a cipher is a brute-force search of the key space; that is, testing all possible keys, in an attempt to recover the plaintext used to produce a particular ciphertext. ...
For an example that involves computing, consider an email protocol like the Simple Mail Transfer Protocol (SMTP). An SMTP client can send messages to any server that conforms to SMTP's specification. Actual applications can be (for example) an aircraft with an SMTP server receiving messages from a ground controller over a radio-based internet link. Any SMTP client can correctly interact with any SMTP server, because they both conform to the same protocol specification, RFC2821, RT49764368. For other senses of this word, see protocol. ...
Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. ...
This paragraph informally provides some examples of layers, some required functionalities, and some protocols that implement them, all from the realm of computing protocols. For other senses of this word, see protocol. ...
- At the lowest level, bits are encoded in electrical, light or radio signals by the Physical layer. Some examples include RS-232, SONET, and WiFi.
- A somewhat higher Data link layer such as the point-to-point protocol (PPP) may detect errors and configure the transmission system.
- An even higher protocol may perform network functions. One very common protocol is the Internet protocol (IP), which implements addressing for large set of protocols. A common associated protocol is the Transmission control protocol (TCP) which implements error detection and correction (by retransmission). TCP and IP are often paired, giving rise to the familiar acronym TCP/IP.
- A layer in charge of presentation might describe how to encode text (ie: ASCII, or Unicode).
- An application protocol like SMTP, may (among other things) describe how to inquire about electronic mail messages.
These different tasks show why there's a need for a software architecture or reference model that systematically places each task into context. This article does not cite any references or sources. ...
RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ...
Synchronous Optical Networking, commonly known as SONET, is a standard for communicating digital information over optical fiber. ...
Wi-Fi (or Wi-fi, WiFi, Wifi, wifi), short for Wireless Fidelity, is a set of standards for wireless local area networks (WLAN) currently based on the IEEE 802. ...
This article does not cite any references or sources. ...
In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ...
The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ...
The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ...
The presentation layer is the sixth level of the seven layer OSI model. ...
Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ...
The Unicode Standard, Version 5. ...
Electronic mail, abbreviated e-mail or email, is a method of composing, sending, and receiving messages over electronic communication systems. ...
The software architecture of a program or computing system is the structure or structures of the system, which comprise software elements, the externally visible properties of those elements, and the relationships between them. ...
The reference model usually used for protocol layering is the OSI seven layer model, which can be applied to any protocol, not just the OSI protocols of the International Organization for Standardization (ISO). In particular, the Internet Protocol can be analysed using the OSI model. “ISO†redirects here. ...
Reliability Assuring reliability of data transmission involves error detection and correction, or some means of requesting retransmission. It is a truism that communication media are always faulty. The conventional measure of quality is the number of failed bits per bits transmitted. This has the useful feature of being a dimensionless figure of merit that can be compared across any speed or type of communication media. In computer science and information theory, error correction consists of using methods to detect and/or correct errors in the transmission or storage of data by the use of some amount of redundant data and (in the case of transmission) the selective retransmission of incorrect segments of the data. ...
In computer science and information theory, error correction consists of using methods to detect and/or correct errors in the transmission or storage of data by the use of some amount of redundant data and (in the case of transmission) the selective retransmission of incorrect segments of the data. ...
A truism is a claim that is so obvious or self-evident as to be hardly worth mentioning, except as a reminder or as a rhetorical or literary device. ...
In dimensional analysis, a dimensionless number (or more precisely, a number with the dimensions of 1) is a pure number without any physical units. ...
In telephony, links with bit error rates (BER) of 10-4 or more are regarded as faulty (they interfere with telephone conversations), while links with a BER of 10-5 or more should be dealt with by routine maintenance (they can be heard). In telecommunication, Telephony encompasses the general use of equipment to provide voice communication over distances. ...
In telecommunication, an error ratio is the ratio of the number of bits, elements, characters, or blocks incorrectly received to the total number of bits, elements, characters, or blocks sent during a specified time interval. ...
For other uses, see Telephone (disambiguation). ...
Data transmission often requires bit error rates below 10-12. Computer data transmissions are so frequent that larger error rates would affect operations of customers like banks and stock exchanges. Since most transmissions use networks with telephonic error rates, the errors caused by these networks must be detected and then corrected.
Communications systems detect errors by transmitting a summary of the data with the data. In TCP (the internet's Transmission Control Protocol), the sum of the data bytes of packet is sent in each packet's header. Simple arithmetic sums do not detect out-of-order data, or cancelling errors. A bit-wise binary polynomial, a cyclic redundancy check, can detect these errors and more, but is slightly more expensive to calculate. A cyclic redundancy check (CRC) is a type of function that takes as input a data stream of any length and produces as output a value of a certain fixed size. ...
Communication systems correct errors by selectively resending bad parts of a message. For example, in TCP when a checksum is bad, the packet is discarded. When a packet is lost, the receiver acknowledges all of the packets up to, but not including the failed packet. Eventually, the sender sees that too much time has elapsed without an acknowledgement, so it resends all of the packets that have not been acknowledged. At the same time, the sender backs off its rate of sending, in case the packet loss was caused by saturation of the path between sender and receiver. (Note: this is an over-simplification: see TCP and congestion collapse for more detail) Message in its most general meaning is an object of communication. ...
A checksum is a form of redundancy check, a simple way to protect the integrity of data by detecting errors in data that are sent through space (telecommunications) or time (storage). ...
The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ...
In data networking and queueing theory, network congestion occurs when incremental increases in offered load lead either only to small increases in network throughput, or to an actual reduction in network throughput. ...
In general, the performance of TCP is severely degraded in conditions of high packet loss (more than 0.1%), due to the need to resend packets repeatedly. For this reason, TCP/IP connections are typically either run on highly reliable fiber networks, or over a lower-level protocol with added error-detection and correction features (such as modem links with ARQ). These connections typically have uncorrected bit error rates of 10-9 to 10-12, ensuring high TCP/IP performance. The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet runs. ...
Automatic Repeat-reQuest (ARQ) is an error control method for data transmission which makes use of acknowledgments and timeouts to achieve reliable data transmission. ...
Resiliency Re addresses a form of network failure known as topological failure in which a communications link is cut, or degrades below usable quality. Most modern communication protocols periodically send messages to test a link. In phones, a framing bit is sent every 24 bits on T1 lines. In phone systems, when "sync is lost", fail-safe mechanisms reroute the signals around the failing equipment. In telecommunications, T-carrier is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America and Japan. ...
In packet switched networks, the equivalent functions are performed using router update messages to detect loss of connectivity. In computer networking and telecommunications, packet switching is a communications paradigm in which packets (messages or fragments of messages) are individually routed between nodes, with no previously established communication path. ...
This article is about a computer networking device. ...
Standards organizations Most recent protocols are assigned by the IETF for Internet communications, and the IEEE, or the ISO for other types. The ITU-T handles telecommunications protocols and formats for the public switched telephone network (PSTN). The ITU-R handles protocols and formats for radio communications. As the PSTN. radio systems, and Internet converge, the different sets of standards are also being driven towards technological convergence. The Internet Engineering Task Force (IETF) is charged with developing and promoting Internet standards. ...
The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ...
“ISO†redirects here. ...
The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU) and is based in Geneva, Switzerland. ...
The public switched telephone network (PSTN) is the concatenation of the worlds public circuit-switched telephone networks, in much the same way that the Internet is the concatenation of the worlds public IP-based packet-switched networks. ...
The ITU Radiocommunication Sector (ITU-R) is a standards body subcommittee of the International Telecommunication Union (ITU) relating to radio communication. ...
Technological convergence is the modern presence of a vast array of different types of technology to perform very similar tasks. ...
Protocol families A number of major protocol stacks or families exist, including the following: A protocol stack (sometimes communications stack) is a particular software implementation of a computer networking protocol suite. ...
Open standards:
Proprietary standards: The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. ...
This article or section does not adequately cite its references or sources. ...
The abbreviation FTP can refer to: The File Transfer Protocol used on the Internet. ...
Universal Plug and Play (UPnP) is a set of computer network protocols promulgated by the UPnP Forum. ...
iSCSI is a protocol that allows clients (called initiators) to send SCSI commands (CDBs) to SCSI storage devices (targets) on remote servers. ...
Network File System (NFS) is a network file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network as easily as if the network devices were attached to its local disks. ...
AppleTalk is a proprietary suite of protocols developed by Apple Inc for computer networking. ...
DECnet is a proprietary suite of network protocols created by Digital Equipment Corporation, originally released in 1975 in order to connect two PDP-11 minicomputers. ...
IPX/SPX stands for Internetwork Packet Exchange/Sequenced Packet Exchange. ...
In computer networking, Server Message Block (SMB) operates as an application-level network protocol mainly applied to shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. ...
Server message block (SMB) is a network protocol mainly applied to share files, printers, serial ports, and miscellaneous communications between nodes on a network. ...
Systems Network Architecture (SNA) is IBMs proprietary networking architecture created in 1974. ...
The Apple Filing Protocol (AFP) is a layer 6 (presentation layer) network protocol that offers file services for Mac OS X and Classic Mac OS. In Mac OS X, AFP is one of several file services supported including Server Message Block (SMB), Network File System (NFS), File Transfer Protocol (FTP...
In computing, rsync is a computer program for Unix systems which synchronizes files and directories from one location to another while minimizing data transfer using delta encoding when appropriate. ...
For other uses, see Unison (disambiguation). ...
See also For other senses of this word, see protocol. ...
A connection-oriented networking protocol is one which identifies traffic flows by some connection identifier rather than by explicitly listing source and destination addresses. ...
In telecommunications, connectionless describes communication between two network end points in which a message can be sent from one end point to another without prior arrangement. ...
This is an incomplete list of individual network protocols, categorized by their nearest OSI model layers. ...
In computing, network architecture is the design of a computer network. ...
In data networking and queueing theory, network congestion occurs when incremental increases in offered load lead either only to small increases in network throughput, or to an actual reduction in network throughput. ...
A tunneling protocol is a network protocol which encapsulates one protocol or session inside another. ...
HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. ...
The abbreviation FTP can refer to: The File Transfer Protocol used on the Internet. ...
References - Radia Perlman: Interconnections: Bridges, Routers, Switches, and Internetworking Protocols. 2nd Edition. Addison-Wesley 1999, ISBN 0-201-63448-1. In particular Ch. 18 on "network design folklore", which is also available online at http://www.awprofessional.com/articles/article.asp?p=20482
- Gerard J. Holzmann: Design and Validation of Computer Protocols. Prentice Hall, 1991, ISBN 0-13-539925-4. Also available online at http://spinroot.com/spin/Doc/Book91.html
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