f time it takes to transmit a bit on the Ethernet channel. Because 100BaseT operates at 10 times the speed of 10-Mbps Ethernet, all timing factors are reduced by the factor of 10. For example, the slot time is 5.12 us rather than 51.2 us. The maximum length of the network is shorter because of the shorter frame transmission time during which possible collisions must be detected. The data rate is increased by a factor of 10 but the frame format and media access control mechanism remain the same as in coaxial Ethernet and 10BaseT. Only a 1-byte start-of-stream delimiter (SSD) and a 1-byte end-of- stream delimiter (ESD) are added in the beginning and end of the frame in Figure 6.27. The topology of the 100BaseT network is equal to the 10BaseT shown in Figures 6.31 and 6.32. Connections between the workstations and a repeater are twisted pairs and their maximum length is 100m. The fast Ether- net standards include both full-duplex and half-duplex connections and operation over two pairs or four unshielded twisted pairs. Table 6.2 shows Ethernet technologies and their main characteristics. Media types show the required twisted-pair quality, where UTP category 3 means ordinary voice- grade twisted pair. The highest quality twisted pair is category 5 and its char- acteristics are specified up to a 100-MHz frequency. Table 6.2 Preferential Order of Ethernet Technologies on Twisted Pair Throughput/ Technology Mode Connection Media 1000BaseTX Full duplex 2 X 1 Gbps 4p UTP 5 1000BaseTX Half duplex 1 Gbps 4p UTP 5 100BaseTX Full duplex 2 X 100 Mbps 2p UTP 5/STP 100BaseT2 Half duplex 100 Mbps 2p UTP 3/4/5 100BaseT4 Half duplex 100 Mbps 4p UTP 3/4/5 100BaseTX Half duplex 100 Mbps 2p UTP 5/STP 10BaseT Full duplex 2 X 10 Mbps 2p UTP 3/4/5 10BaseT Half duplex 10 Mbps 2p UTP 3/4/5 Data Communications The Manchester coding used in 10-Mbps Ethernet is not suitable for higher data rates because it has very wide spectrum as explained in Chapter 4. Figure 4.18 shows that at 100 Mbps it has a strong spectrum at frequencies up to 200 MHz