stations back off and try again. That's the "collision detection" part. Ethernet is the most common example of a CSMA/CD LAN. Originally released as a 10 Mbps product based on IEEE standard 802.3, Ethernet rapidly became the most widely deployed LAN technology in the world. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Premises Technologies Chapter 5 As bandwidth-hungry applications such as E-Commerce, Enterprise Resource Planning (ERP), and Web access evolved, transport technolo- gies advanced, and bandwidth availability (and capability) grew, 10 Mbps Ethernet began to show its age. Today, new versions of Ethernet have emerged that offer 100 Mbps (Fast Ethernet) and 1,000 Mbps (Gigabit Ethernet) transport, with plans afoot for even faster versions. Furthermore, in keeping with the demands being placed on LANs by convergence, standards are evolving for LAN-based voice transport mechanisms that guarantee quality of service for mixed traffic types. Gigabit Ethernet has become a fundamentally important technology as its popularity and level of deployment have climbed. Emerging appli- cations certainly make the case for Gigabit Ethernet's bandwidth capa- bility: LAN telephony, server interconnection, and video to the desktop all demand low-latency solutions, and Gigabit Ethernet may be posi- tioned to provide it. Many vendors have entered the marketplace includ- ing Alcatel, Lucent Technologies, Nortel Networks, and Cisco Systems. The other aspect of the LAN environment that began to show weak- nesses was the overall topology of the network itself. LANs are broadcast environments, which means that when a station transmits, every station on the LAN segment hears the message (Figure 5-20). While this is a simple implementation scheme, it is also wasteful of bandwidth, since stations hear broadcasts that they have no reason to hear. In response t