Carrier extension for gigabit/second ethernet networks operable up to at least 200 m distances

摘要

Transmission rates of 1 Gb/sec. at up to at least 200 m diameter distances are achieved in an Ethernet environment by functionally decoupling frame size to network roundtrip time. This decoupling is achieved by extending the duration of the minimum size event to exceed the network roundtrip time. This extension of the carrier event is made without extending the data field and without altering the frame check sequence. Code implementing the media access control layer and reconciliation layer at the transmitting and receiving end of the network is modified such that at 1 Gb/sec. half-duplex, non-data symbols are appended to the end of short packet frames. The collision window is extended to include these symbols, which extension symbols are also included in fragment discard calculations. The extension is removed, however, before checking the frame check sequence, and before passing the frame to logical link and control. In a switched environment, the extension is not propagated to network links operating at less than 1000 Mb/sec. flowrates, which feature makes the invention backward compatible with existing slower transmission rate Ethernet networks. In full-duplex Ethernet environments, the media access control does not form the carrier extension.