Macmillan Computer Publishing
The past decade has been witness to the radical evolution of data networks from their humble origins to their current forms. The original Local Area Networks (LANs), were nothing more than coaxial cabling, strung from terminal servers to desktop terminals whose users were treated to monochromatic text displayed on low-resolution cathode ray tubes (CRTs).
In the mid-1980s, wide area networks (WANs), too, were slow and crude. Terminal servers multiplexed access for dozens of users to 9.6Kbps circuits. These circuits connected users to mainframe-based applications that lay hidden in a remote data center.
Today, LANs have metamorphosed into high-bandwidth, high-performance, local area networks that support bandwidth- and CPU-intensive client applications such as live, interactive voice and videoconferencing, as well as e-mail and some of the more traditional forms of data processing.
WANs, too, have experienced radical, evolutionary change. Today, 9.6Kbps is deemed inadequate for most of the needs of even a single user. Just try to give a user a 9.6Kbps modem for use as anything but a paperweight!
WANs, too, have experienced radical, evolutionary change. Today, 9.6Kbps is deemed inadequate for most of the needs of even a single user. Just try to give a user a 9.6Kbps modem for use as anything but a paperweight!
It is important to recognize that the impetus for all these changes has been, and remains, the user's business requirements. The competitive environment of most business entities ensures that any technological innovations that offer competitive advantages--that is, better, cheaper, and/or faster--get accepted. For example, the introduction of the mouse facilitated access to computing by obviating the need for typing skills. Suddenly, almost everyone could use a computer! Personal computers, too, offered countless advantages by distributing intelligence down to the desktop.
Software developers also drove changes by constantly upgrading a dizzying array of increasingly complex products that enabled users to actually use the newly distributed processing power at their fingertips. Together, these innovations quickly made hard-wired connections to terminal servers obsolete.
Into this void came the first generation of LANs. These networks offered almost obscene amounts of bandwidth, such as 1 or 4Mb per second (Mbps), depending on whose network you purchased. Initially, these LANs were used as a more flexible means of connecting users with terminal servers. After all, the users' basic requirements hadn't changed all that much, and the increased bandwidth was more than adequate to support terminal emulation.
Towards the end of the 1980s, this first generation of LANs began to show its age. Once the user community understood that the distributed microprocessors on their desktops could do more than just terminal emulation, their quest for even more bandwidth and for higher performance networking began.
The second generation of LANs were little more than faster versions of their predecessors. 1Mbps Ethernets grew into 10Mbps Ethernets. Similarly, 4Mbps Token Rings were accelerated to 16Mbps. This increase in the clock rates would keep users somewhat satisfied up to the middle of the 1990s.......