Information Technology Reference
In-Depth Information
Maximum lengths for multimode fiber are
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62.5-micrometer fiber: 440 m
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50-micrometer fiber: 550 m
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Maximum length for single-mode fiber (9 micrometers) is 5 km.
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Uses 8B10B encoding with simple NRZ.
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1000BASE-SX Short-Wavelength Gigabit Ethernet
IEEE 1000BASE-SX uses short-wavelength optics over a pair of multimode fiber strands.
The specifications are as follows:
Uses short wave (850 nm)
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Use on multimode fiber
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Maximum lengths:
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62.5-micrometer fiber: 260 m
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50-micrometer fiber: 550 m
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Uses 8B10B encoding with simple NRZ
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1000BASE-CX Gigabit Ethernet over Coaxial Cable
IEEE 1000BASE-CX standard is for short copper runs between servers. The specification
is as follows:
Used on short-run copper
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Runs over a pair of 150-ohm balanced coaxial cables (twinax)
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Maximum length 25 m
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Mainly for server connections
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Uses 8B10B encoding with simple NRZ
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1000BASE-T Gigabit Ethernet over UTP
The IEEE standard for 1000-Mbps Ethernet over CAT 5 UTP was IEEE 802.3ab; it was ap-
proved in June 1999. It is now included in IEEE 802.3-2002. This standard uses the four
pairs in the cable. (100BASE-TX and 10BASE-T Ethernet use only two pairs.) The specifi-
cations are as follows:
CAT 5, four-pair UTP.
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Maximum length 100 m.
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Encoding defined is a five-level coding scheme.
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1 byte is sent over the four pairs at 1250 MHz.
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