Gigabit Ethernet

[1] Ethernet was the result of research conducted at Xerox PARC in the early 1970s, and later evolved into a widely implemented physical and link layer protocol.

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, and allow for clock recovery.

Optical fiber transceivers are most often implemented as user-swappable modules in SFP form or GBIC on older devices.

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.

First, eight bits of data are expanded into four three-bit symbols through a non-trivial scrambling procedure based on a linear-feedback shift register; this is similar to what is done in 100BASE-T2, but uses different parameters.

The Telecommunications Industry Association (TIA) created and promoted a standard similar to 1000BASE-T that was simpler to implement, calling it 1000BASE-TX (TIA/EIA-854).

However, this solution has been a commercial failure,[citation needed] likely due to the required Category 6 cabling and the rapidly falling cost of 1000BASE-T products.

Although it is still used for specific applications where cabling is done by IT professionals, for instance, the IBM BladeCenter uses 1000BASE-CX for the Ethernet connections between the blade servers and the switch modules, 1000BASE-T has succeeded it for general copper wiring use.

[16] This standard is highly popular for intra-building links in large office buildings, co-location facilities and carrier-neutral Internet exchanges.

It is very similar to 1000BASE-SX but achieves longer distances up to 2 km over a pair of multi-mode fibers due to higher quality optics than a SX, running on 1310 nm wavelength lasers.

1000BASE-LX can also run over all common types of multi-mode fiber with a maximum segment length of 550 m. For link distances greater than 300 m, the use of a special launch conditioning patch cord may be required.

1000BASE-LX10 was standardized six years after the initial gigabit fiber versions as part of the Ethernet in the First Mile task group.

It is practically identical to 1000BASE-LX, but achieves longer distances up to 10 km over a pair of single-mode fiber due to higher quality optics.

It is very similar to 1000BASE-LX10 but achieves longer distances up to 40 km over a pair of single-mode fibers due to higher quality optics than a LX10, running on 1310 nm wavelength lasers.

Other, non-standard higher-powered single-strand optics commonly known as "BiDi" (bi-directional) utilize wavelength pairs in the 1490/1550 nm range, and are capable of reaching distances of 20, 40 and 80 km, or greater depending on module cost, fiber path loss, splices, connectors and patch panels.

1000BASE-ZX is a non-standard but multi-vendor[31] term to refer to Gigabit Ethernet transmission using 1,550 nm wavelength to achieve distances of at least 70 km (43 mi) over single-mode fiber.

It is very similar to 1000BASE-LX10 but achieves longer distances up 40–120 km, and up to 18 parallel channels over a pair of single-mode fibers due to higher quality optics than LX10 and use of CWDM, running on 1270-1610 nm wavelength lasers.

It is very similar to 1000BASE-LX10 but achieves longer distances up 40–120 km, and up to 64 to 160 parallel channels over a pair of single-mode fibers due to higher quality optics than LX10 and use of DWDM, running on 1528-1565 nm wavelength lasers.

[citation needed] IEEE 802.3bv-2017 defines standardizes Gigabit Ethernet over step-index plastic optical fiber (POF) using -R 64b/65b large block encoding with red light (600–700 nm).