Question

- 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 *10^8 m/s, and transmission rate 2 Mbps? More generally, how long does it take a packet of length L to propagate over a link of distance d, propagation speed s, and transmission rate R bps? Does this delay depend on packet length? Does this delay depend on transmission rate?

Answer 1

It will take 0.01 s or 10 ms

Solution:

As per the question:

Length of the packet, L = 1,000 bytes =
`1000* 8 = 8000 bits`

Distance, d = 2500 km =
`2.5* 10^(6)\ m`

Speed of propagation, s =
`2.5* 10^(8)\ m/s`

Transmission rate, R = 2 Mbps

Now,

Propagation time, t can be calculated as:

`t = (d)/(s) = (2.5* 10^(6))/(2.5* 10^(8)) = 0.01\ s`

t = 10 ms

• In general, propagation time, t is given by:

`t = (link\ distance)/(Propagation\ speed)`

• No, this delay is independent of the length of the packet.
• No, this delay is independent of the rate of transmission.