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Two hosts are connected via a packet switch with 107 bits per second links. Each link has a propagation delay of 20 microseconds. The switch begins forwarding a packet 35 microseconds after it receives the same. If 10000 bits of data are to be transmitted between the two hosts using a packet size of 5000 bits, the time elapsed between the transmission of the first bit of data and the reception of the last bit of the data in microseconds is __________.
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- 175
- 75
- 100
- 125
Correct Option: A
| Transmission time for 5000 bits = Time for 500 bits to travel = | = 50 microseconds | |
| 107 |
So, after 50 microseconds the packet is completely transmitted. But the packet must reach at the other and this happens exactly after propagation delay which is 20 microseconds. So, the switch receives packet after 50 + 20 = 70 microseconds.
According to question, switch forwards after 35 microseconds.
So, after 70 + 35 = 105 microseconds, the switch forwards the packet and at 105 + 70 = 175 microseconds the receiver receives the last bit of data.
