computer network A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...

ing, cell relay refers to a method of statistically multiplexing small fixed-length packets, called "cells", to transport data between computers or kinds of network equipment. It is a reliable,

connection-oriented Connection-oriented communication is a network communication mode in telecommunications and computer networking, where a communication session or a semi-permanent connection is established before any useful data can be transferred. The establish ...

packet switched In telecommunications, packet switching is a method of grouping data into '' packets'' that are transmitted over a digital network. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the pack ...

data

communications protocol A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics and synchr ...

Transmission Rates

Cell relay transmission rates usually are between 56

kbit/s In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multi ...

and several

gigabits per second In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multi ...

. ATM, a particularly popular form of cell relay, is most commonly used for home

DSL Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric di ...

connections, which often runs between 128 kbit/s and 1.544

Mbit/s In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multi ...

( DS1), and for high-speed backbone connections (

OC-3 Optical Carrier transmission rates are a standardized set of specifications of transmission bandwidth for digital signals that can be carried on Synchronous Optical Networking (SONET) fiber optic networks. Transmission rates are defined by rate of t ...

and faster). Cell relay protocols have neither flow control nor

error correction In information theory and coding theory with applications in computer science and telecommunication, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable communica ...

capability, are information-content independent, and correspond only to layers one and two of the

OSI Reference Model The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communications ...

. Cell relay can be used for delay- and jitter-sensitive traffic such as voice and video.

How Cell Relay Works

Cell relay systems break variable-length user packets into groups of fixed-length cells, that add addressing and verification information.

Frame A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent. Frame and FRAME may also refer to: Physical objects In building construction *Framing (con ...

length is fixed in

networking hardware Networking hardware, also known as network equipment or computer networking devices, are electronic devices which are required for communication and interaction between devices on a computer network. Specifically, they mediate data transmission in ...

, based on time delay and user packet-length considerations. One user data message may be segmented over many cells. Cell relay systems may also carry bitstream-based data such as PDH traffic, by breaking it into streams of cells, with a lightweight synchronization and clock recovery shim. Thus cell relay systems may potentially carry any combination of stream-based and packet-based data. This is a form of

statistical time division multiplexing Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation (DBA). In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bitrate digital channels or ...

. Cell relay is an implementation of fast packet-switching technology that is used in connection-oriented broadband integrated services digital networks (

B-ISDN In the 1980s, the telecommunications industry expected that digital services would follow much the same pattern as voice services did on the public switched telephone network, and conceived an end-to-end circuit switched service, known as Broadband ...

, and its better-known supporting technology ATM) and connectionless

IEEE 802.6 IEEE 802.6 is a standard governed by the American National Standards Institute, ANSI for Metropolitan Area Networks (MAN). It is an improvement of an older standard (also created by ANSI) which used the Fiber distributed data interface (FDDI) netwo ...

switched multi-megabit data service (

SMDS Switched Multi-megabit Data Service (SMDS) was a connectionless service used to connect LANs, MANs and WANs to exchange data, in early 1990s. In Europe, the service was known as Connectionless Broadband Data Service (CBDS). SMDS was specified ...

). At any time there is information to be transmitted; the switch basically sends the data units. Connections don't have to be negotiated like circuit switching. Channels don't have to be allocated because channels do not exist in ATM, and on condition that there is an adequate amount of bandwidth to maintain it, there can be indefinite transmissions over the same facility. Cell relay utilizes data cells of a persistent size. Frames are comparable to data packets; however they contrast from cells in that they may fluctuate in size based on circumstances. This type of technology is not secure for the reason that its procedures do not support error handling or data recovery. Per se, all delicate and significant transmissions may perhaps be transported faster via fixed-sized cells, which are simpler to transmit compared to variable-sized frames or packets.

Reliability

Cell relay is extremely reliable for transporting vital data. Switching devices give the precise method to cells as each endpoint address embedded in a cell. An example of cell relay is ATM, a prevalent form utilized to transfer a cell with a fixed size of 53 bytes.

References

* *Minoli, Daniel, and Michael Vitella. ATM and Cell Relay Service for Corporate Environments. New York: McGraw-Hill, 1994. Print. *Minoli, Daniel, and George Dobrowski. Principles of Signaling for Cell Relay and Frame Relay. Boston: Artech House, 1995. Print. *Minoli, Daniel, and George Dobrowski. Principles of Signaling for Cell Relay and Frame Relay. Boston: Artech House, 1995. Print. *Any Transport over MPLS - Cisco Systems." Cisco Systems, Inc. Web. 29 Nov. 2011. . *Davidson, Robert P. Broadband Networking ABCs for Managers: ATM, BISDN, Cell/frame Relay to SONET. New York: John Wiley & Sons, 1994. Print. *Conti, Marco, Enrico Gregori, and Luciano Lenzini. Metropolitan Area Networks. London: Springer, 1997. Print. {{Reflist Multiplexing Network protocols Packets (information technology) fr:Commutation de paquets