How long does it take a packet of length 1,000 bytes to propagate over a link of distance 2,500 km, propagation speed 2.5 x [tex]10^{8}[/tex] m/s, and transmission rate 2 Mbps?
4.01 ms
The total time(T) taken for the packet to propagate over the link is the sum of the delay in transmission ([tex]T_{d}[/tex]) and the delay in propagation ([tex]T_{p}[/tex]).
i.e T = [tex]T_{d}[/tex] + [tex]T_{p}[/tex] -----------------------(i)
Where
(1) [tex]T_{d}[/tex] is the quotient of the packet length (L) in bits and the transmission rate (R) in bits per second.
=> [tex]T_{d}[/tex] = L / R ---------------------- (ii)
=> L = 1000 bytes = 1000 x 8 bits = 8 000 bits
=> R = 2 Mbps = 2 x 1 000 000 = 2 000 000 bps
Substituting the values of L and R into equation (ii) we have,
=> [tex]T_{d}[/tex] = 8000/2000000
=> [tex]T_{d}[/tex] = 4 ms
(2)[tex]T_{p}[/tex] is the quotient of the distance (d = 2500km) of the link and the propagation speed of the link (s = 2.5 x [tex]10^{8}[/tex] m/s)
=> [tex]T_{p}[/tex] = d / s
=> [tex]T_{p}[/tex] = 2500 / 2.5 x [tex]10^{8}[/tex]
=> [tex]T_{p}[/tex] = 0.01 ms
(3) Recall that the time taken (T) for the packet to propagate is ;
=> T = [tex]T_{d}[/tex] + [tex]T_{p}[/tex]
Substituting the values of [tex]T_{d}[/tex] and [tex]T_{p}[/tex] into the equation gives;
=> T = 4 + 0.01
=> T = 4.01 ms
Therefore the time taken is 4.01 ms
Answer:
10 ms
Explanation:
Length of packet = 1000 bytes
Distance of link = 2500 km
Propagation Speed = 2.5 x 10^8 m/s
Transmission Rate = 2 Mpbs
To find: Time a packet takes to propagate over a link
Propagation Time = ?
Solution:
Propagation Time = Distance of Link/Propagation Speed
tprop = d/s=
Distance is in kilometers. First convert it into meters.
2500*1000 = 2500000 meters
Distance of link = 2500000 m
Propagation Speed = 2.5 x 10^8 = 2.5 x 100000000 = 250000000
Propagation Time = (2500*)/(2.5*10^8)
= 2500000/250000000
=0.01 sec
Convert 0.01 second into millisecond:
0.01 x 1000 = 10 ms
So
Propagation Time = 10 ms
