Gigabit Ethernet(redirected from 802.3ab)
Gigabit EthernetAn 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.
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 CABLEEncoding Cable RangeStandard Method Type (meters)1000Base-T802.3ab 4D-PAM5 Cat5-UTP 100 1000Base-TXTIA/EIA-854 4D-PAM5 Cat6-UTP 100 1000Base-CX802.3z 8B/10B Cat1-STP 25 OPTICAL CABLE (8B/10B Encoding)Fiber ModalDiameter 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-LX802.3z 62.5 multimode 500 550 50 multimode 400 500 50 multimode 500 550 9 singlemode --- 5000