gigabit Ethernet interface
For Gigabit Ethernet, there are different interfaces for optical fibers, single- mode fibers and multimode fibers and for STP cables, as well as one, the 1000Base-KX, for backplanes. The GbE interfaces can be traced back to the four basic variants 1000Base-LX, 1000Base- SX, 1000Base-CX and 1000Base-T.
The physical definition for the first three variants comes from Fibre Channel. They work with different wavelengths, which is expressed in the notation for Ethernet interfaces. Thus the letter "L" of 1000 Base-LX or 1000Base- LH stands for "Long". And this Long refers to the wavelength of 1,310 nm. The letter "S", on the other hand, stands for Short and expresses a wavelength of 850 nm, and the letter "C" for Copper, i.e. for twisted pair cable.
The LX variant can be operated with different wavelengths and with single-mode and multimode fibers. When using multimode fibers, the distance is 550 m. The LX variant can also be used with single mode fibers for distances of up to 3 km. The SX variant operates with 850 nm wavelength over multimode fiber for distances up to 220 m (62.5/125 µm) or 550 m (50/125 µm). The CX variant is specified for Gigabit Ethernet over STP cable with 150 ohms for a length of 25 m and the 1000Base-T variant for four-pair STP or FTP cable ofcategory 5 with up to 100 m. It must be taken into account for all length specifications that these are achieved in full duplex operation, i.e. without CSMA/ CD.
New duplex FOC connectors were introduced for Gigabit Ethernet in March 1997: The Galaxy connector, the Mini- MT connector, and several others. The aim of these new developments is to offer an inexpensive and more compact alternative to the duplex SC connector.