Find the total sum of transmission and propagation delays in transmitting the file from S to D?

Consider a source computer (S) transmitting a file of size 106 bits to a destination computer (D) over a network of two routers (R1 and R2) and three links (L1, L2 and L3). L1 connects S to R1;L2 connects R1 to R2; and L3 connects R2 to D. Let each link be of length 100km. Assume signals travel over each link at a speed of 10^8 meters per second. Assume that the link bandwidth on each link is 1Mbps. Let the file be broken down into 1000 packets each of size 1000 bits. Find the total sum of transmission and propagation delays in transmitting the file from S to D?

(A) 1005ms
(B) 1010ms
(C) 3000ms
(D) 3003ms

1Comment
Ajith Supramani @ajithsupramani
12 Jan 2017 11:19 pm

Option (A) 1005 ms

Tt=1ms and Tp=1ms for one packet

after 6ms, the 1st packet reaches D and remaining 999 packets are followed the 1st packet.(i.e, the second packet being transmit to L3 while 1st packet propagated to destination)

so, 6ms + 999 ms =1005ms