<P> Carrier - sense multiple access with collision detection (CSMA / CD) is a media access control method used most notably in early Ethernet technology for local area networking . It uses carrier - sensing to defer transmissions until no other stations are transmitting . This is used in combination with collision detection in which a transmitting station detects collisions by sensing transmissions from other stations while it is transmitting a frame . When this collision condition is detected, the station stops transmitting that frame, transmits a jam signal, and then waits for a random time interval before trying to resend the frame . </P> <P> CSMA / CD is a modification of pure carrier - sense multiple access (CSMA). CSMA / CD is used to improve CSMA performance by terminating transmission as soon as a collision is detected, thus shortening the time required before a retry can be attempted . </P> <P> The following procedure is used to initiate a transmission . The procedure is complete when the frame is transmitted successfully or a collision is detected during transmission . </P> <Ol> <Li> Is my frame ready for transmission? If yes, it goes on to the next point . </Li> <Li> Is medium idle? If not, wait until it becomes ready . </Li> <Li> Start transmitting and monitor for collision during transmission . </Li> <Li> Did a collision occur? If so, go to collision detected procedure . </Li> <Li> Reset retransmission counters and end frame transmission . </Li> </Ol>

4. describe the csma/cd and csma/ca processes