There are four different physical layer standards for gigabit Ethernet using optical fiber (1000BASE-X), twisted pair cable (1000BASE-T), or balanced copper cable (1000BASE-CX). The IEEE 802.3z standard includes 1000BASE-SX for transmission over multi-mode fiber, 1000BASE-LX for transmission over single-mode fiber, and the nearly obsolete 1000BASE-CX for transmission over balanced copper cabling. These standards use 8b/10b encoding, which inflates the line rate by 25%, from 1000 Mbit/s to 1250 Mbit/s to ensure a DC balanced signal. The symbols are then sent using NRZ.
IEEE 802.3ab, which defines the widely used 1000BASE-T interface type, uses a different encoding scheme in order to keep the symbol rate as low as possible, allowing transmission over twisted pair. Ethernet in the First Mile later added 1000BASE-LX10 and 1000BASE-BX10. Eoptolink manufactures Multi-Rate 100Mb/1.25G for up to 200km distances.

Part No.	Data Rate	Wavelength	Source	Distance	DDM (optional)	Application
						FE / GbE	FC	FTTx
EOLS-8512-02	1.25G;MM	850nm	VCSEL	550m
EOLS-1312-2M	1.25G;MM	1310nm	FP	2km
EOLS-1312-10	1.25G;SM	1310nm	FP	10km
EOLS-1312-15	1.25G;SM	1310nm	FP	15km
EOLS-1312-20	1.25G;SM	1310nm	FP	20km
EOLS-1312-30	1.25G;SM	1310nm	FP	30km
EOLS-1312-40	1.25G;SM	1310nm	DFB	40km
EOLS-1512-40	1.25G;SM	1550nm	DFB	40km
EOLS-1512-60	1.25G;SM	1550nm	DFB	60km
EOLS-1512-80	1.25G;SM	1550nm	DFB	80km
EOLS-1512-A	1.25G;SM	1550nm	DFB	100km
EOLS-1512-B	1.25G;SM	1550nm	DFB	120km
EOLS-1512-C	1.25G;SM	1550nm	DFB	160km