Varieties
There are five physical layer standards for gigabit Ethernet using optical fiber (1000BASE-X), twisted pair cable (1000BASE-T), or balanced copper coaxial 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.
IEEE 802.3ap defines Ethernet Operation over Electrical Backplanes at different speeds.
Ethernet in the First Mile later added 1000BASE-LX10 and -BX10.
| Name | Medium | Specified distance |
|---|---|---|
| 1000BASE‑CX | Twinaxial cabling | 25 meters |
| 1000BASE‑KX | Copper backplane | 1 meter |
| 1000BASE‑SX | Multi-mode fiber | 220 to 550 meters dependent on fiber diameter and bandwidth |
| 1000BASE‑LX | Multi-mode fiber | 550 meters |
| 1000BASE‑LX | Single-mode fiber | 5 km |
| 1000BASE‑LX10 | Single-mode fiber using 1,310 nm wavelength | 10 km |
| 1000BASE‑EX | Single-mode fiber at 1,310 nm wavelength | ~ 40 km |
| 1000BASE‑ZX | Single-mode fiber at 1,550 nm wavelength | ~ 70 km |
| 1000BASE‑BX10 | Single-mode fiber, over single-strand fiber: 1,490 nm downstream 1,310 nm upstream | 10 km |
| 1000BASE‑T | Twisted-pair cabling (Cat‑5, Cat‑5e, Cat‑6, or Cat‑7) | 100 meters |
| 1000BASE‑TX | Twisted-pair cabling (Cat‑6, Cat‑7) | 100 meters |
Read more about this topic: Gigabit Ethernet
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