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 Tfr must be at least
two times the maximum propagation time Tp .
Tfr = 2 x Tp.

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 90 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