CSMA/CD

its a computer networking topic

1. Welcome to my presentation

2. CSMA/CD CSMA/CD means Carrier Sense Multiple Access with Collision Detection When a station is sending data,it continuously monitors if transmission was successful,the station is finished. If however there is a collision,it resends the data.

3. Fig:Collision of the first bit in CSMA/CD

4. Minimum Frame Size Before sending the last bit of the frame,the sending station must detect a collision. The frame transmission time T fr must be at least two times the maximum propagation time T p . T fr = 2 x T p.

5. ii. Constantly monitor while sending frame. i. Using a persistence method Procedure iii. Send a short jamming signal to notify that a collision has occurred.

6. Fig:flow diagram for the CSMA/CD

7. Energy Level The level of energy in a channel can have three values: i. Zero level : the channel is idle. ii. Normal level : sending a frame. iii. Abnormal level : there is a collision and the level of energy is twice the normal level

8. Fig:Energy level during transmission,idleness or collision

9. Throughput For 1 persistent method the maximum throughput is around 50 percent when G=1 For nonpersistent method the maximum throughput can go up to 9 0 percent when G is between 3 and 8. The throughput of CSMA/CD is greater than that of pure or slotted ALOHA.

10. Any Question

11. Thank You