Overview

Ethernet and IEEE 802.3 (ISO/IEC8802-3) networks are termed Local Area Networks (LANs) since, by their conventional definition, they can span only relatively local geographic areas. Traditionally, LANs would span no more than say 10kms, and ran at speeds that did not exceed 100Mbps. Wide Area Networks (WANs) on the other hand, would potentially enjoy worldwide coverage but would be limited to speeds of only say 2Mbps. Today, our definitions are changing in line with advances in technology. The differentiation between LANs and WANs is fast becoming a gray area and the term "Metropolitan Area Network" (MAN) of the early 1990s is used far less today. For example, in this volume we see examples of technologies such as the Fiber Distributed Data Interface (FDDI) that broke the bounds of the more traditional view of a LAN, and introduced the MAN to our glossary of terms. Also, since the move is to now join these LANs by faster and faster WAN links, we are now actively burying the LAN/WAN distinction as we move to seamless LAN-to-LAN communications.

Faster, larger, FDDI networks were heralded as being a panacea that would cure the bandwidth ills imposed by the early Ethernet/802.3 and Token Ring technologies. Today, our humble Ethernet network can run at Gigabit speeds (1000Mbps) - ten times faster than FDDI, and at a fraction of the cost. Likewise, the 155Mbps Asynchronous Transfer Mode (ATM) network is complex and expensive, and therefore severely threatened by anything that is relatively simple, cost...