CSMA(Carrier sense multiple access)
Csma is nothing but before transferring the packets from one host to another host it first senses the channel[i.e whether the channel is in ideal state or busy state]
If it is ideal then it can use the channel
If it is busy we have 3 persistent techniques
- 1)1-Persistent
- 2)Non-Persistent
- 3)P-Persistent
In addition it has no Acknowledgement concept
Vulnerability time=Tp
Possibility of collision occurs as every device sends first bits without knowing other channels
As we discussed earlier if channel is busy then we have 3 techniques listed above
1)1-Persistent
It will continuously sense channel until station comes to know that channel is idle[i.e free]
Possibility of collision is more as two or more stations transfer packets[i.e all hosts think that as channel is free every host will start sending their packets
2)Non-persistent
Station will wait for random amount of time and then it senses the channel
reduces Efficiency as we cant access channel even if it is in idle state
3)P-Persistent
The p-persistent strategy combines the advantage of other two approaches[i.e],
a)It reduces the chance of collision
b)It improves efficiency
The Difference between pure aloha and csma is
a)Only sends first bit in csma
b)No ack concept in csma
c)Before transferring frames it will first sense channel whether it is ideal or busy
