A node X on a 10 Mbps network is regulated by a token bucket. The token bucket…
2017
A node X on a 10 Mbps network is regulated by a token bucket. The token bucket is filled at a rate of 2 Mbps. Token bucket is initially filled with 16 megabits. The maximum duration taken by X to transmit at full rate of 10 Mbps is _________ secs.
- A.
1
- B.
2
- C.
3
- D.
4
Attempted by 149 students.
Show answer & explanation
Correct answer: B
Final answer: 2 seconds
Reasoning:
Transmission rate = 10 Mbps.
Token fill rate = 2 Mbps.
Initial tokens = 16 megabits.
Let t be the maximum time to transmit at full rate. After t seconds, available tokens = 16 + 2t (megabits), and the bits sent = 10t (megabits). To sustain full-rate sending these must be equal, so:
Set up the equation: 16 + 2t = 10t.
Rearrange: 16 = (10 - 2) t = 8 t.
Solve: t = 16 / 8 = 2 seconds.
Alternative interpretation: net token consumption while sending at full rate is 10 - 2 = 8 Mbps, so the initial 16 megabits last for 16/8 = 2 seconds.