Question

A node wants to communicate with another node that is 3000 meters away. The transmitted signal propagates at a speed of 3 * 10^8 m/s. The node sends frames of length 1500 bytes at a data rate of 1Gbps. The node employs Stop-and-Wait flow control.

A receiver's clock drifts at a rate of 0.5 seconds every day. The receiver can synchronize itself with the transmitter at the beginning of each frame but not during the frame. It samples the middle of a bit to decode whether it's a 0 or 1. Will the system described above work well with such a receiver? What is the maximum frame size that will work?

Answer 1

Here the clock is drifting at the receiver side, the system will not work well. As the receiver is not able to merge the packets and forward them. The maximum frame size is the one whose transmission time is less than the drift time.

if T_t = 0.5 seconds

bandwidth = 1Gbps = 10⁹ bps

Transmission time(T_t) = length of frame / bandwidth

length of frame = T_t* bandwidth = 0.5 * 10⁹ = 5*10⁸ bits

converting length into bytes =  (5*10⁸) / 8 = 6.25 * 10⁷ bytes

Answer : the maximum frame size that will work fine is 6.25 * 10⁷ bytes