Question

Suppose there is exactly one packet switch between a sending user and a receiving user. The transmission rates between the sending user and the switch and between the switch and the receiving user are R1 and R2, respectively. Assuming that the switch uses store-and-forward packet switching, what is the total end-to-end delay to send a packet of length L?

Answer 1

Answer:

$L(\frac{1}{R_1}+\frac{1}{R_2} )$

Explanation:

$R_1$ is the transmission rates between the sending user and the switch while $R_2$ is the transmission rates between the switch and the receiving user and the length of the packet is L

Considering no propagation delay the time taken to transmit the packet from the sending user to the switch is given as:

$t_1=\frac{L}{R_1}$

the time taken to transmit the packet from the switch to the receiving user is given as:

$t_2=\frac{L}{R_2}$

therefore the total end-to-end delay to send a packet is:

$t=t_1+t_2=\frac{L}{R_1}+\frac{L}{R_2} =L(\frac{1}{R_1}+\frac{1}{R_2} )$