After reading some books and sources I understand that the CSMA p-persistent protocol works like this:
- if the channel is idle, it transmits with probability
p, and with probability
1 - pit defers to the next slot; if that slot is also idle, it repeats this step;
- if the channel is busy, it waits until the channel is idle, and then applies the above step.
Just to mention one of the many sources: Computers Network (A. Tanenbaum, 5th edition) provides the above algorithm at page 267.
But this doesn't sound right to me. If the chosen value of
p is 0, it means that the algorithm is going to defer the transmission with a probability of 1, always. So it will always defer and never transmit anything.
Also, if the channel is initially found idle, why should the algorithm wait? Isn't that an useless waste of resources?
So is this considered the correct algorithm? Shouldn't it be changed to wait only once with a probability of
1 - p and then send? Otherwise the transmission could be deferred a possibly infinite number of times.