UGC NET CSE | June 2019 | Part 2 | Question: 83

Question

You are designing a link layer protocol for a link with bandwidth of $1$ Gbps ($10^9$ bits/second) over a fiber link with length of $800$ km. Assume the speed of light in this medium is $200000$ km/second. What is the propagation delay in this link?

• A. $1$ millisecond
• B. $2$ milliseconds
• C. $3$ milliseconds
• D. $4$ milliseconds

Answer 1

Propagation delay : Time taken by the first bit to travel from sender to receiver end of the link.

Propagation delay = distance/transmission speed = d/s

Propagation delay = 800km/200000km/sec

                                  =4ms

Answer 2

1 sec =1000 mil sec

and propagation delay=distance/velocity

here distance=800 km and velocity=200000 km/sec

so, Tp=800/200000=1/250 sec

1/250 *1000=4 mil sec

Answer 3

Propagation delay : Time taken by the first bit to travel from sender to receiver end of the link.

Propagation delay = distance/speed of the medium = d/s

Propagation delay = 800km/200000km/sec

                                 =(800/200000)sec

                                =(800/200)milliseconds

                                =4 milliseconds