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+1 vote

Assume the propagation delay in a broadcast network is $5 \: \mu s$ and the frame transmission time is $10 \: \mu s$. How long does it take for the last bit to reach the destination after the first bit has arrived?

  1. $10 \: \mu s$
  2. $5 \: \mu s$
  3. $15 \: \mu s$
  4. $50 \: \mu s$
asked in Computer Networks by Boss (15.3k points)
edited by | 152 views
is A the answer
is answer option c)
the delay between first and last bit will be equal to transmission time. that's why i said 10.
The definition of propagation delay is the time taken for the first bit on the link to reach the other side

The definition of transmission delay is the time taken for the first bit to be placed on the link

So here 10 for transmitting the frame on to the link and 5 to propagate to other end

=> 15 micro seconds

2 Answers

+6 votes
Best answer
question is how long it takes for last bit to reach destination after first bit has already arrived. therefore here we have to take difference of their time.
for first bit their will be no transmission time  hence total 5.
for last bit we have to first transmit all the bits hence total time is 10+5=15;
time difference is 10. hope u get it now.
answered by Junior (973 points)
selected by
0 votes

the last bit take the time 2*PT (2*5=10) because we have transmit up to 2*pt  time until to detect the collision in the channel

plz correct me if i m wrong 

answered by Active (1.9k points)
reshown by
10 is correct but the reason is wrong.
ok sir

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