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CBS (committed burst size)

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Committed Burst Size (CBS) is a traffic policing algorithm that is used to limit the amount of traffic that is allowed to pass through a network device. CBS is often used in conjunction with other traffic management techniques such as rate limiting, shaping, and queuing to ensure that network traffic is managed in a way that is fair, efficient, and reliable.

In this article, we will provide an in-depth explanation of CBS, including how it works, how it is implemented, and its benefits and limitations.

What is Committed Burst Size (CBS)?

Committed Burst Size (CBS) is a term used in the context of the Asynchronous Transfer Mode (ATM) protocol to refer to the maximum amount of data that can be transmitted over a virtual circuit during a fixed time interval. CBS is used to ensure that the rate of traffic sent over a network does not exceed a predetermined limit.

CBS is a mechanism that is used to control the rate of data transmission by regulating the amount of data that is allowed to be transmitted in a burst. CBS works by allowing the network to transmit a burst of data up to a certain size before the transmission is limited to a lower rate for the remainder of the transmission interval.

The CBS algorithm ensures that the amount of data that is transmitted is within the agreed-upon limits of the network capacity. CBS is used to ensure that the rate of traffic sent over a network does not exceed a predetermined limit.

How Does CBS Work?

CBS works by allowing the transmission of data at a rate that is equal to or less than the capacity of the network. CBS uses a token bucket algorithm to determine the rate at which data can be transmitted. The token bucket algorithm works by adding tokens to a bucket at a fixed rate. Each token in the bucket represents a certain amount of data that can be transmitted.

When data is transmitted over the network, tokens are removed from the bucket to represent the amount of data that has been transmitted. When the number of tokens in the bucket reaches zero, the transmission of data is stopped until new tokens are added to the bucket.

CBS adds an additional layer of control over the rate at which data is transmitted. CBS specifies the maximum amount of data that can be transmitted in a burst, known as the Committed Burst Size (CBS). The CBS is typically set to a value that is less than the maximum bandwidth of the network. When data is transmitted, the CBS allows for a burst of data to be transmitted up to the size of the CBS. Once the CBS has been reached, the transmission rate is reduced to the network's maximum rate.

The CBS algorithm is used to ensure that the transmission rate of data is equal to or less than the capacity of the network. CBS is used in conjunction with other traffic management techniques to ensure that network traffic is managed in a way that is fair, efficient, and reliable.

Implementing CBS

The implementation of CBS varies depending on the network equipment and the specific requirements of the network. CBS can be implemented using hardware, software, or a combination of both. The following is a general overview of how CBS can be implemented:

  1. Define the CBS: The first step in implementing CBS is to define the Committed Burst Size (CBS). The CBS is typically set to a value that is less than the maximum bandwidth of the network. The CBS can be defined as the maximum amount of data that can be transmitted in a burst during a fixed time interval.
  2. Implement the Token Bucket Algorithm: The next step in implementing CBS is to implement the Token Bucket Algorithm. The Token Bucket Algorithm works by adding tokens to a bucket at a fixed rate. Each token in the bucket represents a certain amount of data that can be transmitted.

When data is transmitted over the network, tokens are removed from the bucket to represent the amount of data that has been transmitted. When the number of tokens in the bucket reaches zero, the transmission of data is stopped until new tokens are added to the bucket.

  1. Monitor Traffic: The next step in implementing CBS is to monitor network traffic. This is typically done using network monitoring tools that track the amount of traffic that is being transmitted over the network.
  2. Control Traffic: Once network traffic has been monitored, the CBS algorithm can be used to control the rate at which data is transmitted. If the rate of data transmission exceeds the CBS, the transmission rate is reduced to the maximum rate of the network.
  3. Modify the CBS: The CBS can be modified based on the specific requirements of the network. For example, if the network capacity changes, the CBS can be adjusted to ensure that the rate of data transmission remains within the capacity of the network.

Benefits and Limitations of CBS

CBS provides several benefits when used in conjunction with other traffic management techniques. Some of the benefits of CBS include:

  1. Ensures Fairness: CBS ensures that all users of the network are treated fairly. By limiting the rate of data transmission, CBS ensures that no single user can dominate the network, which can lead to congestion and slower transmission rates.
  2. Efficient Use of Network Resources: CBS ensures that the network resources are used efficiently. By controlling the rate of data transmission, CBS ensures that the network is not overwhelmed with traffic, which can cause delays and dropped packets.
  3. Reliable Transmission: CBS ensures that data is transmitted reliably. By controlling the rate of data transmission, CBS ensures that packets are not dropped due to network congestion.

However, CBS also has some limitations. Some of the limitations of CBS include:

  1. Limited Burst Capacity: CBS has a limited burst capacity, which means that it may not be suitable for networks that require high bursts of traffic.
  2. Complexity: CBS can be complex to implement and configure, which may require specialized knowledge and expertise.
  3. Overhead: CBS can add additional overhead to the network, which can reduce the available bandwidth.

Conclusion

Committed Burst Size (CBS) is a traffic policing algorithm that is used to limit the amount of traffic that is allowed to pass through a network device. CBS ensures that the rate of traffic sent over a network does not exceed a predetermined limit. CBS works by allowing the transmission of data at a rate that is equal to or less than the capacity of the network. CBS is used in conjunction with other traffic management techniques to ensure that network traffic is managed in a way that is fair, efficient, and reliable.

Implementing CBS involves defining the Committed Burst Size, implementing the Token Bucket Algorithm, monitoring traffic, controlling traffic, and modifying the CBS based on the specific requirements of the network. CBS provides several benefits, including fairness, efficient use of network resources, and reliable transmission. However, CBS also has some limitations, including limited burst capacity, complexity, and additional overhead.