Question

A computer on a 6-Mbps network is regulated by a token bucket. The token bucket is filled at a rate of 1 Mbps. It is initially filled to capacity with 8 megabits. How long can the computer transmit at the full \(6 \mathrm{Mbps}\) ?

Short answer

1.6 seconds

Step-by-step solution

Understanding the Problem

The token bucket is a traffic-shaping algorithm that controls how data is transmitted. In this scenario, it allows the computer to transmit at 6 megabits per second (Mbps) but the bucket fills only at 1 Mbps and starts with an initial 8 megabits (Mb). Our goal is to find out how long the computer can transmit at this rate before the bucket is depleted.

Calculate Consumption Rate

The computer transmits data at a rate of 6 Mbps. This means each second, 6 megabits of data are consumed from the token bucket.

Calculate Bucket Refill Rate

The token bucket is refilled at a rate of 1 Mbps. This means each second, 1 megabit is added to the bucket.

Calculate Net Consumption Rate

Since the bucket refills by 1 Mbps but the computer transmits at 6 Mbps, the net consumption rate is the difference between these two rates.Net consumption rate: \[ (6 ext{ Mbps} - 1 ext{ Mbps}) = 5 ext{ Mbps} \]This means that each second, the token bucket effectively will lose 5 megabits.

Compute the Time Until Depletion

The token bucket starts with 8 megabits and loses 5 megabits each second due to the net consumption rate. To find the time it will take to deplete these 8 megabits, we can use the formula:Time until depletion:\[ \frac{\text{Initial tokens}}{\text{Net consumption rate}} = \frac{8 ext{ Mb}}{5 ext{ Mbps}} \]Solving this gives:\[ \frac{8}{5} = 1.6 ext{ seconds} \]

Key concepts

Network Traffic Shaping

Network traffic shaping is a crucial process in managing how data packets are transmitted over a network. Imagine a freeway with traffic lights that regulate the flow of cars. In the digital world, these lights are algorithms like the "Token Bucket Algorithm". They help ensure all data gets transmitted smoothly and without overwhelming the network.

The goal of traffic shaping is to optimize or guarantee performance, improve latency, or increase usable bandwidth for certain packets. This means certain data, especially critical or time-sensitive information, can be prioritized to travel across the network faster.

• Reduces congestion by controlling data flow.
• Ensures fair bandwidth distribution among users.
• Prioritizes certain types of network traffic.

Traffic shaping helps maintain efficiency and reliability. It is foundational in networks, ensuring that data transmission aligns with expected quality standards.

Data Transmission Rate

The data transmission rate refers to how fast data is sent over the network, typically measured in bits per second (bps). In our example, the transmission rate is initially at 6 megabits per second (Mbps).

This rate determines how quickly information can be sent and received, affecting everything from downloading files to streaming videos. The higher the rate, the faster the transfer occurs, improving the responsiveness of applications and overall user experience.

• Provides critical insight into network performance.
• Affects applications' real-time data needs like video calls or gaming.
• Directly linked to the speed users perceive on their devices.

Understanding and managing data transmission rates is vital to ensuring networks can handle current and future demands efficiently.

Token Refill Rate

The token refill rate is a key concept in the token bucket algorithm, dictating how many tokens are added to the "bucket" each second. In our setup, this rate is 1 Mbps, meaning 1 megabit is added to the bucket every second, which allows sending more data once tokens are available.

Consider it similar to drizzling rain refilling a water tank. The refill rate ensures there is a steady availability of tokens that can be used for data transmission. Without a sufficient refill rate, the system cannot sustain high data transmission for an extended period.

• Helps regulate the flow of outgoing data packets.
• Ensures a balance between data being sent out and data prepared for future transmission.
• Acts as a buffer to absorb traffic spikes without overwhelming the network.

The token refill rate is a pivotal part of ensuring stable and controlled data flow across networks.