##### Consider two nodes A and C at a distance 2000m. Suppose station A star...

Consider two nodes A and C at a distance 2000m. Suppose station A starts sending a long frame at time t1=0; station C starts sending a long frame at time t2= 3 microseconds. Find the number of bits station A has sent before detecting the collision? Assume, data rate as 10 Mbps and propagation speed 2*10^8 m/s.

A) 70 bits

B) 65 bits

C) 130 bits

D) 140 bits

A) 70 bits

B) 65 bits

C) 130 bits

D) 140 bits

now if you see at t=3microsec C start and that time A will be covered 3 micro sec distance between A and C .

Now after 3.5 more microsec both collide..that time will be 6.5 micro second for A from t=0.

To detect collision A need to still transmit data ...that means signal need to travel for another 6.5 microsec to reach A.

here total time to detect the collision 13micro sec,till this time 130 bit will be transmitted by A.

I hope this will help you!!!

Sir, I couldn't understand this statement "Now if you see at t=3microsec B start (I guess you meant C here) and that time A will be covered 3 micro sec distance between A and C. Now after 3.5 more microseconds both collide. (How ?)that time will be 6.5 microseconds for A from t=0."

it was typo....now i have correct it.When i am saying they will collide after 3.5 more microseconds...this means they are using same band width so will travel same distance ....as you can see in time and distance ques...speed same for both source then they will travel equal distance...

Same like that they will collide after 3.5 second ..when C starts,That time A have transmitted for 6.5Micro second.

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