1 The Internet, Email, Ebusiness and the Worldwide Web (www) Nowadays every self-respecting person (particularly if a grandparent!) has a per- sonal email address. And many modern companies have encompassed ebusiness. They have prestigious Internet ‘domain names’ (advertised with modern lower case company names) and run Worldwide Web (www) sites for advertising and order- taking. What has stirred this revolution? The Internet. But when, why and how did data networking and interworking start? And how did the Internet evolve? Where will it lead? And what does all that frightful jargon mean? (What are the acronyms and the protocols?). In this chapter we shall find out. We shall talk about the emer- gence of computer networking, the Worldwide Web (www), about ISPs (Internet service providers) and about where the Internet started — in the US Defense Depart- ment during the 1970s. We discuss the significance of the Internet Protocol (IP) today, and where it will lead. And most important of all — we start ‘unravelling’ the jargon. 1.1 In the beginning — ARPANET The beginnings of the Internet are to be found in the ARPANET,theadvanced research project agency network. This was a US government-backed research project, which initially sought to create a network for resource-sharing between American universities. The initial tender for a 4- node network connecting UCLA (University of California, Los Angeles), UCSB (University of California, Santa Barbara), SRI (Stanford Research Institute) and the University of Utah took place in 1968, and was won by BBN (Bolt, Beranek and Newman). The network nodes were called Internet message processors (IMPs), and end-user computing devices were connected to these nodes by a protocol called 1822 (1822 because the Internet engineering note (IEN) number 1822 defined the protocol). Subsequently, the agency was increasingly funded by the US military, and consequently, from 1972, was renamed DARPA (Defense Advanced Research Project Agency). These beginnings have had a huge influence on the subsequent development of computer data networking and the emergence of the Internet as we know it today. BBN became a leading manufacturer of packet switching equipment. A series of protocols developed which are sometimes loosely referred to either as TCP/IP (transmission control protocol/Internet protocol) or as IP (Internet protocol). Correctly they are called the ‘IP-protocol suite’. They are defined in documents called RFCs (request for comment) generated under the auspices Data Networks, IP and the Internet: Protocols, Design and Operation Martin P. Clark 2003 John Wiley & Sons, Ltd ISBN: 0-470-84856-1 2 The Internet, email, ebusiness and the worldwide web (www) of the Internet Engineering Task Force (IETF). The current most-widely used version of the Internet protocol (IP) — version 4 or IPv4 — is defined in RFC 791. The current version of TCP (transmission control protocol) is defined in RFC 793. 1.2 The emergence of layered protocols for data communication In parallel with the development of the ARPANET, a number of standardised layered proto- col ‘stacks’ and protocol suites for simplifying and standardising the communication between computer equipment were being developed independently by various different computer and telecommunications equipment manufacturers. Most of these protocols were ‘proprietary’. In other words, the protocols were based on the manufacturers’ own specifications and docu- mentation, which were kept out of the public domain. Many manufacturers believed at the time that ‘proprietary’ protocols gave both a ‘competitive advantage’ and ‘locked’ customers into using their own particular brand of computer hardware. But the principles of the various schemes were all similar, and the ideas generated by the various groups of developers helped in the development of the standardised protocols which came later. All data communications protocols are based upon packet switching, a form of electronic inter-computer communication advanced by Leonard Kleinrock of MIT (Massachusetts Insti- tute of Technology — and later of UCLA — University of California in Los Angeles) in his paper ‘Information flow in large communication networks’ (July 1961). The term packet switching itself was coined by Donald Davies of the UK’s National Physical Laboratory (NPL) in 1966. Packet switching is analogous to sending letters through the post — the data content, anal- ogous to a page of a letter is the user content (or payload) of a standard packet. The user content is packed in the packet or frame (analogous to an ‘envelope’) and labelled with the destination address. When the size of a single packet is too small for the message as a whole, then the message can be split up and sent as a sequence of numbered packets, sent one after another (see Figure 1.1). The networking nodes (which in different types of data networks have different names: routers, switches, bridges, terminal controllers, cluster controllers, front-end Figure 1.1 Post Office analogy illustrating the principles of packet switching. SNA (systems network architecture) 3 processors, etc.) all essentially work like a postal sorting office. They read the ‘address’ on each packet (without looking at the contents) and then forward the packet to the appropriate next node nearer the destination. The best-known, most successful and widely used of the 1970s generation of packet- switching protocols were: • SNA (systems network architecture) — the networking protocols used for interconnecting IBM (International Business Machines) computers; • DECnet — the networking protocols used for interconnecting computers of the Digital Equipment Corporation (DEC); • X.25 (ITU-T recommendation X.25) and its partner protocol, X.75. This was the first attempt, coordinated by the International Telecommunications Union standardisation sector (ITU-T), to create a ‘standard’ protocol — intended to enable computers made by different manufacturers to communicate with one another — so-called open systems interconnec- tion (OSI). 1.3 SNA (systems network architecture) The systems network architecture (SNA) was announced by IBM in 1974 as a standardised communications architecture for interconnecting all the different types of IBM computer hard- ware. Before 1974, transferring data or computer programs from one computer to another could be a time-consuming job, sometimes requiring significant manual re-formatting, and often requiring the transport of large volumes of punched cards or tapes. Initially, relatively few IBM computers were capable of supporting SNA, but by 1977 the capabilities of the third generation of SNA (SNA-3) included: • communication controllers (otherwise called FEPs or front end processors) — hardware which could be added to mainframe computers for taking over communication with remote devices; • terminal controllers (otherwise called cluster controllers) — by means of which, end-user terminals (teletypes or computer VDUs, video display units) could be connected to a remote host computer; • the possibility to connect remote terminal controllers to the mainframe/communication controller site using either leaselines or dial-in lines; • the possibility of multi-host networks (terminals connected to multiple mainframe computers — e.g., for bookkeeping, order-taking, personnel, etc. — by means of a single communications network). Figure 1.2 illustrates the main elements of a typical SNA network, showing the typical star topology. Point-to-point lines across the wide area network (WAN) connect the front end processor (FEP or communications controller) at the enterprise computer centre to the terminals in headquarters and remote operations offices. The lines used could be either leaselines, point- to-point X.25 (i.e., packet-switched) connections, frame relay connections or dial-up lines. During the 1980s and 1990s, SNA-based networks were widely deployed by companies which used IBM mainframe computers. At the time, IBM mainframes were the workhorse of the computing industry. The mainframes of the IBM S/360, S/370 and S/390 architectures became well known, as did the components of the SNA networks used to support them: 4 The Internet, email, ebusiness and the worldwide web (www) Figure 1.2 A typical SNA network interconnecting IBM computer hardware. • Front end processor (FEP or communication controller) hardware: IBM 3705, IBM 3725, IBM 3720, IBM 3745; • Cluster controller hardware: IBM 3174, IBM 3274, IBM 4702, IBM 8100; • VTAM (virtual telecommunication access method) software used as the mainframe com- munications software; • CICS (communication information control system) mainframe management software; • NCP (network control program) front end processor communications control software; • NPSI (NCP-packet switching interface) mainframe/FEP software for use in conjunction with X.25-based packet-switched WAN data networks; • TSO (time sharing option) software allowing mainframe resources to be shared by many users; • NetView mainframe software for network monitoring and management; • APPN (advanced peer-to-peer networking) used in IBM AS-400 networks; • ESCON (enterprise system connection): a high-speed ‘channel’ connection interface between mainframe and front-end processor; • Token ring local area network (LAN). Due to the huge popularity of IBM mainframe computers, the success of SNA was assured. But the fact that SNA was not a public standard made it difficult to integrate other manufacturers’ network and computer hardware into an IBM computer network. IBM introduced products