The Gigabit Ethernet (standard IEEE 802.3z ) is the evolution to 1000Mbit / s protocol Fast Ethernet (IEEE 802.3u) operating at 100 Mbit / s.

There are Major amendments to the Protocol for Fast Ethernet processin. Gigabit Ethernet has become necessary to introduce changes to the IEEE 802.3u, in particular:

Remove the 4B/5B encoding (125Mbps), and adopt the 8B/10B encoding variants 1000BaseSX, 1000BaseLX and 1000BaseCX and encoding PAM (pulse-amplitude modulation) 5X5 (in the variant 1000BaseT).

They used the 4 wire pairs UTP simultaneously (in the variant 1000BaseT to 500Mbps), 2 pairs of STP simultaneously (in the variant 1000BaseCX to 500Mbps) and multimode fiber (1000BaseSX variants, 1000BaseLX).

The transmission becomes full-duplex (500Mbps full-duplex).
5 levels per symbol is used instead of 3 (1000Mbps full-duplex).
We use a Forward Error Correction (FEC) to recover 6 dB .
It decreased the Bit Time from 10ns to 1ns.
It decreased the ' Inter-packet gap of 96ns to 0.96μs.
Is decreased the time slot to be 5.12μs 4.096μs.
Introduces the frame bursting , that is, a station can transmit multiple packets in succession without releasing the transmission medium to the burst-limit which is of 65536 bits (8192 octets), the first package still has to be extended by Carrier Extension , if too short .
Carrier Extension is introduced, namely, the extension of 4096bit packet size, or created specifically with real data.