TABLE OF CONTENTS The 802.3z GigE standard describes multiple optical specifications for GigE. 1000BaseSX describes short wavelength (850 nm) transmission using MMF with a maximum range of 550 m on new fiber or 220 m on older fiber (with lower-quality dispersion characteristics). 1000BaseLX describes long-wavelength (1,310 nm) transmission using either MMF (with a range of 550 m) or SMF (with a range of 5,000 m). Similar to standards development for Fast Ethernet, the standards committee took advantage of existing technology and borrowed the transceivers and encoding formats of the Fibre Channel standard. The 8B/10B encoding format was used, which specifies the framing and clock-recovery mechanism. One significant change was the signaling rate, which was increased to 1.25 Gbps from Fibre Channel s 1.06 Gbps. The frame content and size are the same as previous Ethernet implementations (10BaseT and 100BaseT).
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Like the deployment of Fast Ethernet, the range of commercially available optical GigE interfaces exceeds the limits outlined by the IEEE 802.3z Committee. Devices that operate at 1,550 nm and ones that operate at much greater distances than 5 km are available. In fact, 150 km spans are...
