What is Gigabit Ethernet

Gigabit Ethernet, as defined by the IEEE 802.3-2005 standard, is a term referring to the different types of technologies developed with the ability to transmit Ethernet frames at a minimum of 1 Gbps. Gigabit Ethernet is available over four different physical layers, which are the following: coaxial cable, twisted pair cable, balanced copper cable and optical fiber.

In June 1998, the first Gigabit Ethernet standard, IEEE 802.3z (more commonly known as 1000BASE-X), was released by the Institute of Electrical and Electronics Engineers (IEEE).

This standard includes the following subdivisions:

1000BASE-LX, developed for data transmission over single-mode fiber, using a long wavelength (1270 to 1355 nm) laser;

1000BASE-SX, developed for data transmission over multi-mode fiber using an 850 nanometer, near infrared (NIR) light wavelength; and

1000BASE-CX was developed for data transmission with a maximum distances of 25 meters over balanced copper cabling using balanced shielded twisted pair.

These three standards employ an 8B/10B encoding, inflating the line rate from 1000 Mbps to 1250 Mbps in order to ensure a DC balanced signal. A non-return-to-zero (NRZ) line code is then used to transmit the symbols.

In 1999, IEEE 802.3ab (known as 1000BASE-T) was released, defining gigabit Ethernet transmission over Category 5, 5e (which stands for "5 enhanced") or 6 unshielded twisted pair (UTP) cabling. The ratification of this standard established Gigabit Ethernet as a desktop technology, enabling organizations to utilize their existing copper wiring infrastructure for the standard.

It uses all four cable pairs for simultaneous transmission in both uplink and downlink through echo cancellation and a technique known as 5-level pulse amplitude modulation. IEEE ratified a faster 10 GB fiber-based standard in 2000, followed by a twisted pair cabling standard in 2006.

An easier-to-implement version of 1000BASE-T, known as 1000BASE-TX (TIA/EIA-854), was developed by the Telecommunications Industry Association (TIA). It was more tolerant of poorly installed wiring than 1000BASE-T, and was supposed to reduce the cost by requiring only two pairs rather than four; however, the cables required were Category 6, which was considerably expensive. 1000BASE-TX wound up being a commercial failure.

There are also 1000BASE-ZX and 1000BASE-LH, which are accepted by the industry but are non-standard terms referring to Gigabit Ethernet transmission using 1550 nm wavelength over single-mode fiber, achieving distances of 70 km and further.

Gigabit Ethernet was originally deployed in high-capacity backbone network links, although in 2000, mass produced personal computers featuring the 1000BASE-T connection were released, beginning with the Power Mac G4 and PowerBook G4 of Apple, Inc.

Editorial Team at Geekinterview is a team of HR and Career Advice members led by Chandra Vennapoosa.

Editorial Team – who has written posts on Online Learning.

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