Scaling CSMA/CD to 1 Gb/s with frame bursting

Abstract

In Gigabit Ethernet, the round-trip propagation delay can be much greater than the transmission time for a minimum length frame. The authors describe some changes to the Ethernet CSMA/CD medium access control algorithm that allow CSMA/CD to be used in this case. First, carrier extension is used to increase the slot time without requiring a corresponding increase in the minimum frame length. Second, frame bursting is introduced so that a host may transmit more than one frame without releasing control of the channel, in a manner that increases the efficiency for small frames without changing its one-frame-at-a-time service interface. Using simulation, they show that CSMA/CD with carrier extension and frame bursting operating on 1 Gb/s links provides a significant performance increase over 100 Mb/s fast Ethernet. These changes are being adopted by the IEEE 802.32 task force, which is currently defining the standard for Gigabit Ethernet.