Gigabit Ethernet
Gigabit Ethernet is an escalation of the Fast Ethernet standard using the same IEEE 802.3 Ethernet frame
format. Gigabit Ethernet offers a throughput of 1,000 Mbps (1 Gbps). Like Fast Ethernet, Gigabit Ethernet is
compatible with earlier Ethernet standards. However, the physical layer has been modified to increase data
transmission speeds: The IEEE 802.3 Ethernet standard and the American National Standards Institute
(ANSI) X3T11 FibreChannel. IEEE 802.3 provided the foundation of frame format, CSMA/CD, full duplex,
and other characteristics of Ethernet. FibreChannel provided a base of high-speed ASICs, optical
components, and encoding/decoding and serialization mechanisms. The resulting protocol is termed IEEE
802.3z Gigabit Ethernet.
Gigabit Ethernet supports several cabling types, referred to as 1000BaseX. Table 1.6 lists the cabling
specifications for each type.
| Technology | Wiring Type | Pairs | Cable Length |
| 1000BaseCX | Shielded Twisted Pair (STP) | 1 | 25 m |
| 1000BaseT | EIA/TIA Category 5 UTP | 4 | 100 m |
| 1000BaseSX | Multimode fiber (MMF) with 62.5 micron core; 850 nm laser Multimode fiber (MMF) with 50 micron core; 1300 nm laser |
1 1 |
275 m 550 m |
| 1000BaseLX/LH | Multimode fiber (MMF) with 62.5 micron core; 1300 nm laser Single-mode fiber (SMF) with 50 micron core; 1300 nm laser Single-mode fiber (SMF) with 9 micron core; 1300 nm laser |
1 1 1 |
550 m 550 m 10 km |
| 1000BaseZX | Single-mode fiber (SMF) with 9 micron core; 1550 nm laser Single-mode fiber (SMF) with 8 micron core; 1550 nm laser |
1 1 |
70 km 100 km |
TABLE 1.6: Gigabit Ethernet Cabling and Distance Limitations