Editing Gigabit Ethernet (section)

== Varieties ==
[[File:Intelpromtserverpcixadapter1000mta342.jpg|thumb|1000BASE-T–capable [[network interface card]] made by [[Intel]], which connects to a computer via [[PCI-X]]]]

There are five [[physical layer]] standards for Gigabit Ethernet using [[optical fiber]] (1000BASE-X), [[twisted pair cable]] (1000BASE-T), or shielded 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 shielded balanced copper cabling. These standards use [[8b/10b encoding]], which inflates the line rate by 25%, from {{nowrap|1000 Mbit/s}} to {{nowrap|1250 Mbit/s}}, to ensure a DC balanced signal, and allow for clock recovery. The symbols are then sent using [[Non-return-to-zero|NRZ]].

Optical fiber transceivers are most often implemented as user-swappable modules in [[Small form-factor pluggable transceiver|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.

IEEE 802.3ap defines Ethernet Operation over Electrical Backplanes at different speeds.

[[Ethernet in the First Mile]] later added 1000BASE-LX10 and -BX10.