The full-duplex version of Gigabit Ethernet is totally compatible with the 10Mbps and 100Mbps versions.
For full-duplex operation, CSMA/CD is not used, and a system can send a frame whenever it wants, except for the fact that frames must be separated by an interframe gap and PAUSE requests must be honored.
Stations connect to a device called a full-duplex repeater or buffered distributor via full-duplex links. The stations share the gigabit bandwidth.
Nonstandard 9018-byte Jumbo frames improve performance by reducing the number of frames that need to be sent, which reduces a station's processing load.
The half-duplex version of Gigabit Ethernet requires modifications to the protocol. At the time of writing, there are no half-duplex ...