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73-604: The Open Systems Interconnection ( OSI ) model is a reference model from the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems interconnection." In the OSI reference model, the communications between systems are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. The model partitions

146-942: A comprehensive description of networking, the model failed to garner reliance during the design of the Internet , which is reflected in the less prescriptive Internet Protocol Suite , principally sponsored under the auspices of the Internet Engineering Task Force (IETF). In the early- and mid-1970s, networking was largely either government-sponsored ( NPL network in the UK, ARPANET in the US, CYCLADES in France) or vendor-developed with proprietary standards, such as IBM 's Systems Network Architecture and Digital Equipment Corporation 's DECnet . Public data networks were only just beginning to emerge, and these began to use

219-428: A corresponding entity at the same layer in another host. Service definitions, like the OSI model, abstractly describe the functionality provided to a layer N by a layer N−1 , where N is one of the seven layers of protocols operating in the local host. At each level N , two entities at the communicating devices (layer N peers ) exchange protocol data units (PDUs) by means of a layer N protocol . Each PDU contains

292-709: A format specified by the application layer during the encapsulation of outgoing messages while being passed down the protocol stack , and possibly reversed during the deencapsulation of incoming messages when being passed up the protocol stack. For this very reason, outgoing messages during encapsulation are converted into a format specified by the application layer, while the conversion for incoming messages during deencapsulation are reversed. The presentation layer handles protocol conversion, data encryption, data decryption, data compression, data decompression, incompatibility of data representation between operating systems, and graphic commands. The presentation layer transforms data into

365-444: A lack of common protocols. For a period in the late 1980s and early 1990s, engineers, organizations and nations became polarized over the issue of which standard , the OSI model or the Internet protocol suite , would result in the best and most robust computer networks. However, while OSI developed its networking standards in the late 1980s, TCP/IP came into widespread use on multi-vendor networks for internetworking . The OSI model

438-584: A light pulse. For example, a 1 bit might be represented on a copper wire by the transition from a 0-volt to a 5-volt signal, whereas a 0 bit might be represented by the transition from a 5-volt to a 0-volt signal. As a result, common problems occurring at the physical layer are often related to the incorrect media termination, EMI or noise scrambling, and NICs and hubs that are misconfigured or do not work correctly. The data link layer provides node-to-node data transfer —a link between two directly connected nodes. It detects and possibly corrects errors that may occur in

511-463: A major advance in the standardisation of network concepts. It promoted the idea of a consistent model of protocol layers, defining interoperability between network devices and software. The concept of a seven-layer model was provided by the work of Charles Bachman at Honeywell Information Systems . Various aspects of OSI design evolved from experiences with the NPL network, ARPANET, CYCLADES, EIN , and

584-477: A network-layer protocol, if the encapsulation of the payload takes place only at the endpoint, GRE becomes closer to a transport protocol that uses IP headers but contains complete Layer 2 frames or Layer 3 packets to deliver to the endpoint. L2TP carries PPP frames inside transport segments. Although not developed under the OSI Reference Model and not strictly conforming to the OSI definition of

657-425: A non-specialist. A reference model is not directly tied to any standards, technologies or other concrete implementation details, but it does seek to provide a common semantics that can be used unambiguously across and between different implementations." There are a number of concepts rolled up into that of a 'reference model.' Each of these concepts is important: There are many uses for a reference model. One use

730-459: A payload, called the service data unit (SDU), along with protocol-related headers or footers. Data processing by two communicating OSI-compatible devices proceeds as follows: The OSI model was defined in ISO/IEC 7498 which consists of the following parts: ISO/IEC 7498-1 is also published as ITU-T Recommendation X.200. The recommendation X.200 describes seven layers, labelled 1 to 7. Layer 1

803-451: A physical layer can be described in terms of the network topology . Physical layer specifications are included in the specifications for the ubiquitous Bluetooth , Ethernet , and USB standards. An example of a less well-known physical layer specification would be for the CAN standard. The physical layer also specifies how encoding occurs over a physical signal, such as electrical voltage or

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876-553: A problem space into basic concepts, a reference model can be used to examine two different solutions to that problem. In doing so, the component parts of a solution can be discussed in relation to one another. For example, if a reference model describes computer systems that help track contacts between a business and their customers, then a reference model can be used by a business to decide which of five different software products to purchase, based on their needs. A reference model, in this example, could be used to compare how well each of

949-449: A problem that concerns a specific set of entities. For example, if a reference model describes a set of business measurements needed to create a balanced scorecard , then each measurement can be assigned to a specific business leader. That allows a senior manager to hold each of their team members responsible for producing high quality results. A fifth use of a reference model is to allow the comparison of different things. By breaking up

1022-444: A remote database protocol to record reservations. Neither of these protocols have anything to do with reservations. That logic is in the application itself. The application layer has no means to determine the availability of resources in the network. Reference model Reference models are often illustrated as a set of concepts with some indication of the relationships between the concepts. According to OASIS (Organization for

1095-468: Is 1500 bytes, the minimum size of a TCP header is 20 bytes, and the minimum size of an IPv4 header is 20 bytes, so the maximum segment size is 1500−(20+20) bytes, or 1460 bytes. The process of dividing data into segments is called segmentation ; it is an optional function of the transport layer. Some connection-oriented transport protocols, such as TCP and the OSI connection-oriented transport protocol (COTP), perform segmentation and reassembly of segments on

1168-564: Is a data link layer protocol that can operate over several different physical layers, such as synchronous and asynchronous serial lines. The ITU-T G.hn standard, which provides high-speed local area networking over existing wires (power lines, phone lines and coaxial cables), includes a complete data link layer that provides both error correction and flow control by means of a selective-repeat sliding-window protocol . Security, specifically (authenticated) encryption, at this layer can be applied with MACsec . The network layer provides

1241-410: Is closest to TCP, although TCP contains functions, such as the graceful close, which OSI assigns to the session layer. Also, all OSI TP connection-mode protocol classes provide expedited data and preservation of record boundaries. Detailed characteristics of TP0–4 classes are shown in the following table: An easy way to visualize the transport layer is to compare it with a post office, which deals with

1314-483: Is not usually a fatal problem. The OSI connection-oriented transport protocol defines five classes of connection-mode transport protocols, ranging from class 0 (which is also known as TP0 and provides the fewest features) to class 4 (TP4, designed for less reliable networks, similar to the Internet). Class 0 contains no error recovery and was designed for use on network layers that provide error-free connections. Class 4

1387-536: Is often an explicit recognition of concepts that many people already share, but when created in an explicit manner, a reference model is useful by defining how these concepts differ from, and relate to, one another. This improves communication between individuals involved in using these concepts. A fourth use of a reference model is to create clear roles and responsibilities. By creating a model of entities and their relationships, an organization can dedicate specific individuals or teams, making them responsible for solving

1460-482: Is still used as a reference for teaching and documentation; however, the OSI protocols originally conceived for the model did not gain popularity. Some engineers argue the OSI reference model is still relevant to cloud computing . Others say the original OSI model does not fit today's networking protocols and have suggested instead a simplified approach. Communication protocols enable an entity in one host to interact with

1533-555: Is the function of the payload that makes these belong to the network layer, not the protocol that carries them. The transport layer provides the functional and procedural means of transferring variable-length data sequences from a source host to a destination host from one application to another across a network, while maintaining the quality-of-service functions. Transport protocols may be connection-oriented or connectionless. This may require breaking large protocol data units or long data streams into smaller chunks called "segments", since

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1606-423: Is the layer of the OSI model that is closest to the end user, which means both the OSI application layer and the user interact directly with a software application that implements a component of communication between the client and server, such as File Explorer and Microsoft Word . Such application programs fall outside the scope of the OSI model unless they are directly integrated into the application layer through

1679-411: Is the lowest layer in this model. The physical layer is responsible for the transmission and reception of unstructured raw data between a device, such as a network interface controller , Ethernet hub , or network switch , and a physical transmission medium . It converts the digital bits into electrical, radio, or optical signals. Layer specifications define characteristics such as voltage levels,

1752-405: Is to create standards for both the objects that inhabit the model and their relationships to one another. By creating standards, the work of engineers and developers who need to create objects that behave according to the standard is made easier. Software can be written that meets a standard. When done well, a standard can make use of design patterns that support key qualities of software, such as

1825-566: The International Network Working Group ( IFIP WG6.1). In this model, a networking system was divided into layers. Within each layer, one or more entities implement its functionality. Each entity interacted directly only with the layer immediately beneath it and provided facilities for use by the layer above it. The OSI standards documents are available from the ITU-T as the X.200 series of recommendations. Some of

1898-500: The National Computing Centre Limited ( NCC Ltd ) and acquired the assets of the original NCC through a pre-pack administration arrangement . This new for-profit company, formed in 2010, initially offered some of the same services as the original NCC but in 2012 became a shell company as it had to file for protection from its creditors and make most of its staff redundant. The National Computing Centre

1971-440: The X.25 standard in the late 1970s. The Experimental Packet Switched System in the UK c.  1973 –1975 identified the need for defining higher level protocols. The UK National Computing Centre publication, Why Distributed Computing , which came from considerable research into future configurations for computer systems, resulted in the UK presenting the case for an international standards committee to cover this area at

2044-400: The teardown , between two or more computers, which is called a "session". Common functions of the session layer include user logon (establishment) and user logoff (termination) functions. Including this matter, authentication methods are also built into most client software, such as FTP Client and NFS Client for Microsoft Networks. Therefore, the session layer establishes, manages and terminates

2117-546: The "voice of the computer user" and offered no substantial services to its client base and became a shell company. In July 2013 the registered address was changed to an accommodation address in London and between then and July 2017 the operational address was at times listed as Aston Abbotts in Buckinghamshire, Bournemouth and Welwyn Garden City. In July 2017, NCC Ltd changed its name to IT Accreditations Limited and

2190-470: The Advancement of Structured Information Standards) a reference model is "an abstract framework for understanding significant relationships among the entities of some environment, and for the development of consistent standards or specifications supporting that environment. A reference model is based on a small number of unifying concepts and may be used as a basis for education and explaining standards to

2263-687: The ISO meeting in Sydney in March 1977. Beginning in 1977, the ISO initiated a program to develop general standards and methods of networking. A similar process evolved at the International Telegraph and Telephone Consultative Committee (CCITT, from French: Comité Consultatif International Téléphonique et Télégraphique ). Both bodies developed documents that defined similar networking models. The British Department of Trade and Industry acted as

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2336-587: The Naked Leader and joint ventures included: the NCC/Ashridge Business School MBA; NCC/AQA Applied ICT; and ProfIT. Funds were spent attempting to develop new products and services including web hosting which did not prove commercially successful. In 2002 NCC adopted a policy of vigorous support for open-source software . Funds were also received from Microsoft towards a software evaluations centre. Contracts were won to support

2409-456: The OSI model has well-defined functions, and the methods of each layer communicate and interact with those of the layers immediately above and below as appropriate. The Internet protocol suite as defined in RFC   1122 and RFC   1123 is a model of networking developed contemporarily to the OSI model, and was funded primarily by the U.S. Department of Defense. It was the foundation for

2482-505: The OSI model started in the late 1970s to support the emergence of the diverse computer networking methods that were competing for application in the large national networking efforts in the world (see OSI protocols and Protocol Wars ). In the 1980s, the model became a working product of the Open Systems Interconnection group at the International Organization for Standardization (ISO). While attempting to provide

2555-634: The UK Royal Mail to Consignia. These survival strategies failed and the National Computing Centre diminished rapidly in size and turnover. NCC continued to make unsustainable losses but there was no change in strategic direction. To stem the losses NCC was forced to rapidly close or dispose of many of the acquisitions at a loss to the organisation. Michael Gough left the business in February 2008. In March 2008, Steve Markwell

2628-399: The ability to extend the software in an inexpensive way. Another use of a reference model is to educate. Using a reference model, leaders in software development can help break down a large problem space into smaller problems that can be understood, tackled, and refined. Developers who are new to a particular set of problems can quickly learn what the different problems are, and can focus on

2701-499: The application layer, known as HTTP, FTP, SMB/CIFS, TFTP, and SMTP. When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. The most important distinction in the application layer is the distinction between the application-entity and the application. For example, a reservation website might have two application-entities: one using HTTP to communicate with its users, and one for

2774-592: The appointment of Rob Cotton as Finance Director and who also took over control of the Escrow division in May of that year, with Morris leaving at that time. Following a substantial fall off of revenues as Y2K came and passed, and due to the failure of the company before this date to invest in its general consultancy, security, system engineering and escrow business during the Y2K period, the group began to make monthly losses before

2847-515: The benefits of the changes to the escrow business instigated by Rob Cotton were felt and the company returned to profitability. Renamed NCC Group, in May 2000, and with escrow now the cornerstone of the group, Rob Cotton led a secondary management buy-out in 2003 valuing NCC Group at £30 million and supported by Barclays Private Equity. At this point, the National Computing Centre sold its shares in NCC Group as did Pearse, Bird and Sadler who left

2920-437: The business having already left its iconic building in 2010 it finally left Manchester. The company was formally recorded at Companies House as being insolvent and in a voluntary arrangement as of 2 March 2012. The insolvency practitioner dealing with the companies affairs was Wilkins Kennedy of London. It would appear that from this point NCC Ltd was no longer recognised by any trade body, association or any part of government as

2993-605: The business. The NCC Group subsequently floated on the AIM stock market in 2004 for £55 million and was listed on the London Stock Exchange in 2007 with a market capitalisation of nearly £390 million as of June 2014. NCC received substantial proceeds from the sale of NCC Group Limited (circa £11 million between 2000 and 2003 plus dividends) and from the multi-million sale of its Manchester city centre buildings (Armstrong House and Oxford House) to Bruntwood Group. Following

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3066-481: The candidate solutions can be configured to meet the needs of a particular business process. Instances of reference models include, among others: National Computing Centre The National Computing Centre ( NCC ) was an independent not-for-profit membership and research organisation in the United Kingdom. After the original organisation was liquidated in 2010, Redholt Limited changed its name to

3139-557: The connections between the local and remote application. The session layer also provides for full-duplex , half-duplex , or simplex operation, and establishes procedures for checkpointing, suspending, restarting, and terminating a session between two related streams of data, such as an audio and a video stream in a web-conferencing application. Therefore, the session layer is commonly implemented explicitly in application environments that use remote procedure calls . The presentation layer establishes data formatting and data translation into

3212-429: The development of the Internet . It assumed the presence of generic physical links and focused primarily on the software layers of communication, with a similar but much less rigorous structure than the OSI model. In comparison, several networking models have sought to create an intellectual framework for clarifying networking concepts and activities, but none have been as successful as the OSI reference model in becoming

3285-551: The dispatch and classification of mail and parcels sent. A post office inspects only the outer envelope of mail to determine its delivery. Higher layers may have the equivalent of double envelopes, such as cryptographic presentation services that can be read by the addressee only. Roughly speaking, tunnelling protocols operate at the transport layer, such as carrying non-IP protocols such as IBM 's SNA or Novell 's IPX over an IP network, or end-to-end encryption with IPsec . While Generic Routing Encapsulation (GRE) might seem to be

3358-573: The fact; the reverse of the traditional approach to developing standards. Although not a standard itself, it was a framework in which future standards could be defined. In May 1983, the CCITT and ISO documents were merged to form The Basic Reference Model for Open Systems Interconnection , usually referred to as the Open Systems Interconnection Reference Model , OSI Reference Model , or simply OSI model . It

3431-518: The flow of data in a communication system into seven abstraction layers to describe networked communication from the physical implementation of transmitting bits across a communications medium to the highest-level representation of data of a distributed application . Each intermediate layer serves a class of functionality to the layer above it and is served by the layer below it. Classes of functionality are implemented in software development using established communication protocols . Each layer in

3504-668: The form that the application layer accepts, to be sent across a network. Since the presentation layer converts data and graphics into a display format for the application layer, the presentation layer is sometimes called the syntax layer. For this reason, the presentation layer negotiates the transfer of syntax structure through the Basic Encoding Rules of Abstract Syntax Notation One (ASN.1), with capabilities such as converting an EBCDIC -coded text file to an ASCII -coded file, or serialization of objects and other data structures from and to XML . The application layer

3577-407: The functional and procedural means of transferring packets from one node to another connected in "different networks". A network is a medium to which many nodes can be connected, on which every node has an address and which permits nodes connected to it to transfer messages to other nodes connected to it by merely providing the content of a message and the address of the destination node and letting

3650-413: The functions of communication, as is the case with applications such as web browsers and email programs . Other examples of software are Microsoft Network Software for File and Printer Sharing and Unix/Linux Network File System Client for access to shared file resources. Application-layer functions typically include file sharing, message handling, and database access, through the most common protocols at

3723-453: The insolvency of the pension fund later that year. Redholt Ltd was owned by a group of six shareholders, including former managers and two Directors of the insolvent National Computing Centre. Redholt Ltd, was renamed as The National Computing Centre Limited (NCC Ltd) in Feb 2011. In 2011 NCC Ltd extended its portfolio of services to include IT consulting, mainly as a virtual organisation through

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3796-502: The network find the way to deliver the message to the destination node, possibly routing it through intermediate nodes. If the message is too large to be transmitted from one node to another on the data link layer between those nodes, the network may implement message delivery by splitting the message into several fragments at one node, sending the fragments independently, and reassembling the fragments at another node. It may, but does not need to, report delivery errors. Message delivery at

3869-449: The network layer imposes a maximum packet size called the maximum transmission unit (MTU), which depends on the maximum packet size imposed by all data link layers on the network path between the two hosts. The amount of data in a data segment must be small enough to allow for a network-layer header and a transport-layer header. For example, for data being transferred across Ethernet , the MTU

3942-426: The network layer is not necessarily guaranteed to be reliable; a network layer protocol may provide reliable message delivery, but it does not need to do so. A number of layer-management protocols, a function defined in the management annex , ISO 7498/4, belong to the network layer. These include routing protocols, multicast group management, network-layer information and error, and network-layer address assignment. It

4015-644: The others being the computer company International Computers Limited (ICL) and chip maker Inmos (both now defunct). Initially, most income came directly from government grants, but with the growth of NCC's commercial operations this ceased in 1989. During the 1970s and 1980s NCC had a joint venture with Blackwell Publishing (NCC Blackwell) which was a significant publisher of academic computing books. Between 1989 and 1996, NCC operated with five main divisions – education, consulting, escrow, membership services, and system engineering deriving income from membership fees and its commercial activities. A valued component

4088-434: The physical layer. It defines the protocol to establish and terminate a connection between two physically connected devices. It also defines the protocol for flow control between them. IEEE 802 divides the data link layer into two sublayers: The MAC and LLC layers of IEEE 802 networks such as 802.3 Ethernet , 802.11 Wi-Fi , and 802.15.4 Zigbee operate at the data link layer. The Point-to-Point Protocol (PPP)

4161-407: The problems that they are being asked to solve, while trusting that other areas are well understood and rigorously constructed. The level of trust is important to allow software developers to efficiently focus on their work. A third use of a reference model is to improve communication between people. A reference model breaks up a problem into entities, or "things that exist all by themselves." This

4234-480: The protocol specifications were also available as part of the ITU-T X series. The equivalent ISO/IEC standards for the OSI model were available from ISO. Not all are free of charge. OSI was an industry effort, attempting to get industry participants to agree on common network standards to provide multi-vendor interoperability. It was common for large networks to support multiple network protocol suites, with many devices unable to interoperate with other devices because of

4307-436: The receiving side; connectionless transport protocols, such as UDP and the OSI connectionless transport protocol (CLTP), usually do not. The transport layer also controls the reliability of a given link between a source and destination host through flow control, error control, and acknowledgments of sequence and existence. Some protocols are state- and connection-oriented . This means that the transport layer can keep track of

4380-675: The retirement of Perkins, Michael Gough was appointed as CEO in 2000 and NCC pursued a new strategy of rapidly developing and expanding its membership services by acquisition. After 2000, and particularly after the second sale of its shares in NCC Group in 2003, acquisitions accelerated to acquire a number of related companies, membership organisations, publications, publishing rights and to fund joint ventures. The acquisitions included: Management Consultancy News; Conspectus; CIO Connect; The Construction Industry Computing Association; Certus; The Evaluation Centre; Institute of IT Training; The Impact Programme; and PMP. Publishing rights acquired included

4453-614: The secretariat, and universities in the United Kingdom developed prototypes of the standards. The OSI model was first defined in raw form in Washington, D.C. , in February 1978 by French software engineer Hubert Zimmermann , and the refined but still draft standard was published by the ISO in 1980. The drafters of the reference model had to contend with many competing priorities and interests. The rate of technological change made it necessary to define standards that new systems could converge to rather than standardizing procedures after

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4526-585: The segments and retransmit those that fail delivery through the acknowledgment hand-shake system. The transport layer will also provide the acknowledgement of the successful data transmission and sends the next data if no errors occurred. Reliability, however, is not a strict requirement within the transport layer. Protocols like UDP, for example, are used in applications that are willing to accept some packet loss, reordering, errors or duplication. Streaming media , real-time multiplayer games and voice over IP (VoIP) are examples of applications in which loss of packets

4599-588: The standard model for discussing and teaching networking in the field of information technology . The model allows transparent communication through equivalent exchange of protocol data units (PDUs) between two parties, through what is known as peer-to-peer networking (also known as peer-to-peer communication). As a result, the OSI reference model has not only become an important piece among professionals and non-professionals alike, but also in all networking between one or many parties, due in large part to its commonly accepted user-friendly framework. The development of

4672-433: The timing of voltage changes, physical data rates, maximum transmission distances, modulation scheme, channel access method and physical connectors. This includes the layout of pins , voltages , line impedance , cable specifications, signal timing and frequency for wireless devices. Bit rate control is done at the physical layer and may define transmission mode as simplex , half duplex , and full duplex . The components of

4745-649: The transport layer, the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol Suite are commonly categorized as layer 4 protocols within OSI. Transport Layer Security (TLS) does not strictly fit inside the model either. It contains characteristics of the transport and presentation layers. The session layer creates the setup, controls the connections, and ends

4818-532: The uptake of IT particularly amongst SMEs including open source software and the Open Source Academy, and the development of an accreditation standard for IT services which became operational in 2009. There was a re-branding exercise in which NCC re-branded as Principia, a brand that was quickly dropped and the NCC brand resumed, a move that seemed to echo a similarly named and disastrous re-branding of

4891-551: The use of independent associate consultants. The 'new' NCC Ltd was not a mutual not-for-profit organisation, but retained some of the member organisations of the liquidated company and initially it delivered some of the same products and services. By the end of 2011, the 'new' NCC Ltd once again faced financial difficulties and in 2012 it sought voluntary arrangements with its creditors to step away from its debts. The company had run up substantial losses, had not paid suppliers and had not filed accounts. Nearly all staff were laid off and

4964-417: Was appointed as Chief Executive but there was no improvement in the company's fortunes or significant change in strategic direction. One significant asset remaining, Filetab , was transferred in 2009 to a new company called NCC Filetab whose managing director was also managing director of NCC. With losses and the size of the pension fund deficit increasing, the company was unable to meet its obligations and

5037-467: Was founded on 10 June 1966 by the Labour government, as an autonomous not-for-profit organisation, in order to be the "voice of the computer user", encourage the growth of computer usage in the UK and ensure that the necessary education and training was made available. NCC was one of the visible outcomes from Harold Wilson 's " White Heat of Technology " speech and the formation of a Ministry of Technology ,

5110-422: Was named NCC Services Limited and later became NCC Group Limited of which the National Computing Centre held a 20% share. John Perkins became the new managing director of National Computing Centre, which remained a not-for-profit membership organisation. The NCC Services Ltd management team of Managing Director Chris Pearse and directors John Morris, Peter Bird, and Chris Sadler was strengthened in March 2000 by

5183-405: Was placed into administration by its management. In February 2010, NCC went into administration and ultimately liquidation. The few remaining assets and intellectual property rights were transferred in a "pre-pack" administration arrangement to Redholt Ltd a new private company, thus distancing the new company from the NCC creditors, which included a substantial pension fund liability resulting in

5256-668: Was published in 1984 by both the ISO, as standard ISO 7498, and the renamed CCITT (now called the Telecommunications Standardization Sector of the International Telecommunication Union or ITU-T ) as standard X.200. OSI had two major components: an abstract model of networking, called the Basic Reference Model or seven-layer model, and a set of specific protocols . The OSI reference model was

5329-805: Was the Computer Validation Service, which ran Validation testing for Fortran 77 and Pascal . These validation tests were issued in accordance with a reciprocal agreement with General Services Administration in the United States. In 1996, the National Computing Centre sold its overseas education business, NCC Education , to stave off a financial crisis that occurred when the company breached its borrowing limits. In 1999, it sold its commercial divisions (turnover of less than £10 million), which provided escrow, consultancy, system engineering services to its existing management team supported by ECI Ventures for £5 million. This new company

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