ervices potentially available in the Network next few years, the ever growing power of computing resources and the continual imagination of business and residential applications in MAINFRAME combining computer and communications as a single platform for services. This chapter examines Local Area Networking (LAN) and Wide Digital Analogue Digital Area Networking (WAN), developments from the early 1960s, the Connection phenomenal leaps of technology recorded during its development, the issues concerning implementing such a network today and the future role of such networks for business and residential com- munities. Figure 56.2 Remote mainframe applications over an analogue network 56.2 Network development Modem as the name suggests modulates and demodulates from In 1960 the term wide and local area networks was as foreign as analogue tone into digital data and vice versa. (See Chapter 39.) In MacDonalds. The wide area network was principally the trans- practice it allowed digital data from a remote terminal to be con- mission network implemented by the dominant monopolitic verted into analogue signals for its onward connection into the PTT/Telco, which was analogue based, with copper reaching to the restrictive (300kHz to 3.4kHz) analogue public network. subscriber and the backbone network pulled together by Frequency Earlier modems such as V22 (1200 baud) and V22 bis (2400 baud) Division Multiplexing (FDM). (See Figure 56.1 and Chapter 20.) offered, in comparison to modern modem, slow speeds. Neverthe- less, these served to provide the initial revolution of Wide Area Networking. Major analogue networks soon appeared as the plat- form for companies to distribute their centralised computing re- Manual Cross Transmission sources. Based principally around IBM's SNA environment they Connect Network become the workhorse of many corporate organisations. (See Figure 56.3) Network Switching Network ANALOGUE Figure 56.1 Analogue Wide Area Network of the 1960s Modem The network was designed to carry analogue voice telephony