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Redirected from: GbE

Definition: Gigabit Ethernet


An Ethernet standard that transmits at 1 gigabit per second. Gigabit Ethernet (GbE, GE) connects PCs and servers in local networks and is commonly employed along with a mix of 10/100 Mbps devices. For example, a 10/100/1000 switch supports all three rates and adjusts to the highest speed between sender and receiver. All new computers and most network devices support Gigabit Ethernet.

GbE transmits full duplex from point to point using Ethernet switches and half duplex in a shared Ethernet hub environment (see CSMA/CD).

IEEE 1000Base-T (802.3ab)
The 1997 standard (IEEE 802.3z) required multimode fiber or shielded copper cables, but two years later, 1000Base-T enabled GbE to run on ordinary Cat 5 copper and be readily used in existing networks. Four wire pairs each transmit 250 Mbps in both directions.

TIA 1000Base-TX
A competing standard created by the TIA that never caught on used simpler electronics but required Cat 6 cabling. However, 1000Base-T is often erroneously labeled 1000Base-TX. See Ethernet and 10 Gigabit Ethernet.

   COPPER CABLE

                Encoding   Cable  Range
   Standard     Method     Type  (meters)

   1000Base-T
   802.3ab      4D-PAM5  Cat5-UTP  100

   1000Base-TX
   TIA/EIA-854  4D-PAM5  Cat6-UTP  100

   1000Base-CX
   802.3z       8B/10B   Cat1-STP   25


   OPTICAL CABLE
   (8B/10B Encoding)

   Fiber            Modal
   Diameter       Bandwidth   Range
   (microns)      (MHz-km)   (meters)

   1000Base-SX
   802.3z
   62.5 multimode   160        220
   62.5 multimode   200        275
   50 multimode     400        500
   50 multimode     500        550

   1000Base-LX
   802.3z
   62.5 multimode   500        550
   50 multimode     400        500
   50 multimode     500        550
    9 singlemode    ---       5000