I had a doubt, CSMA/CD is used by Ethernet. Ethernet is end to end, ie connected between two nodes. I hope, It has different channel for transmission and reception. Then how could a collision occur. Can't understand, correct me if I am wrong. Tell me what I am missing.
CSMA/CD is rarely used these days, and was completely removed with the removal of the half-duplex option in gigabit ethernet spec. Even if there are separate TX and RX lines, the hub could be full-duplex in which case CSMA/CD is in play. To understand CSMA/CD, think of a room full of people: before talking you first listen to see if anyone else (the MA=Multiple Access part) is already talking (the CS=Carrier Sense part), then after you talk you listen for interruptions (the CD=Collision Detection part). ([a single] Ethernet is not always completely end-to-end, BTW)