mechanism for autonegotiation of the media speed as illustrated in Figure 6.34. Ethernet adapters can autosense Introduction to Telecommunications Network Engineering 10-Mbps, 100-Mbps, and 1,000-Mbps operations, and with the help of this standardized feature it is possible to establish Ethernet networks that support all three speeds. Autonegotiation also detects whether a full-duplex (to switch) or half-duplex (to hub) operating mode can be used. Figure 6.34 illustrates the autonegotiation process between the switch and network interface cards (NICs) of workstations. Table 6.2 shows the order of priority of Ethernet technologies. When a workstation is connected to the network, an autonegotiation process takes place and the highest technology in Table 6.2 supported by both ends is used. 6.5.10 Gigabit Ethernet The Gigabit Ethernet provides a 1-Gbps bandwidth with the simplicity of Ethernet at a lower cost than other technologies of comparable speeds. It will offer a natural upgrade path for current Ethernet installations, leveraging existing workstations, management tools, and training. Gigabit Ethernet employs the same CSMA/CD protocol and the same frame format (with carrier extension) as its predecessors. Because Ethernet is the dominant technology for LANs, the vast majority of users can extend their network to gigabit speeds at a reasonable initial cost. They need not reeducate their staff and users and they need not invest in additional protocol stacks. The Gigabit Ethernet is an efficient technology for backbone networks of Ethernet LANs because of the similarity of the technologies. As an exam- ple, for an ATM backbone network the frames of the Ethernet must be I detect on port 1 I detect on port 18 100 Mbps full duplex 10 Mbps half duplex and set port 1 to Switch and set port 18 to 100 Mbps full duplex 10 Mbps half duplex Signaling Figure 6.34 Autonegotiation between switch and NICs of workstations. Data Communications translated into short ATM cells and vice versa. The Gigabit Ethernet back- bone transmi