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Gigabit Ethernet
Media Access Control (MAC)
Gigabit Media Independent Interface (GMII)
1000Base-X
1000Base-T
8B/10B encoder/decoder
encoder/decoder
1000Base-CX
1000Base-LX
1000Base-SX
1000Base-T
Shielded
LWL
SWL
UTP
Balanced
Fiber Optic
Fiber Optic
Cat 5e
Copper
IEEE 802.3ab
IEEE 802.3z physical layer
physical layer
(C) Herbert Haas
2005/03/11
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Gigabit Ethernet has been defined in March 1996 by the working group IEEE
802.3z. The GMII represents a abstract interface between the common Ethernet
layer 2 and different signaling layers below. Two important signaling techniques
had been defines: The standard 802.3z defines 1000Base-X signaling which uses
8B10B block coding and the 802.3ab standard uses 1000Base-T signaling. The
latter is only used over twisted pair cables (UTP Cat 5 or better), while
1000BaseX is only used over fiber, with one exception, the twinax cable
(1000BaseCX), which is basically a shielded twisted pair cable.
BTW: The "X" stands for block coding.
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