Chapter 1, Problem P33P

Explanation of Solution

Given,

Number of bits present in the file is F

Number of segments present in the file is S

Therefore, the length of the packets is S + 80 bits

The transmission rate of each link is R bps

Number of packets present in the packet can be calculated by using the following formula is given below:

$\text{Number}\text{of}\text{packets}\text{=}\frac{\text{Number}\text{of}\text{bits}}{\text{Number}\text{of}\text{segments}}$

Therefore, the number of packets present in the file is $\frac{F}{S}$.

The time required to receive the last packet at first router is $\frac{\text{S}\text{+}\text{80}}{\text{R}}\text{×}\frac{\text{F}}{\text{S}}\sec$.

At $\frac{\text{S}\text{+}\text{80}}{\text{R}}\text{×}\frac{\text{F}}{\text{S}}$ time, the packet $\frac{\text{F}}{\text{S}\text{-}\text{2}}$ will be at destination whereas the packet $\frac{\text{F}}{\text{S}\text{-}\text{1}}$ will be at second router.

The last packet will be transmitted by first and second routers with $\frac{\text{S}\text{+}\text{80}}{\text{R}}\sec$ time delay