I understand that vulnerable time is the time when collision is possible.

In CSMA/CD, the vulnerable time is Tp because it takes Tp time for bit to travel from source to destination and collision might occur during that time.Here Tp is propagation delay.

Even in pure aloha, I understand how is vulnerable time 2*Tt time is derived. Here Tt is transmission time.

My doubt is why don't we add or consider Tp time in pure aloha and Tt time in CSMA/CD when calculating vulnerable time. Why are we ignoring it ?


1 Answer 1


Tp is same as Tt for pure aloha Tfr is also same as Tt

  • 2
    $\begingroup$ Welcome to CS.SE! Thank you for your answer. It would be great if you could edit your answer to provide more explanation to justify your response (e.g., why are they the same?). $\endgroup$
    – D.W.
    Commented May 9, 2022 at 20:07

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