CIR (committed information rate)

Committed Information Rate (CIR) is a service level agreement (SLA) parameter used in telecommunications networks to ensure a certain level of service quality for data traffic. The CIR specifies the minimum guaranteed bandwidth that a network service provider must deliver to a customer at all times, regardless of network congestion or other factors that may affect the quality of service.

In this article, we will explore the concept of CIR in detail, including its importance in network design, how it is calculated, and its applications in different types of networks.

The Importance of CIR in Network Design

In a typical telecommunications network, different types of traffic can compete for the available bandwidth. For example, voice, video, and data traffic all have different bandwidth requirements and quality of service (QoS) requirements. In addition, the network topology, routing protocols, and other factors can affect the performance of the network.

To ensure that the network can provide the required level of service quality for all types of traffic, network designers must consider various performance parameters, such as latency, jitter, and packet loss. CIR is one such parameter that network designers use to ensure that the network can meet the bandwidth requirements of each customer.

Without a CIR guarantee, a customer may experience reduced bandwidth or data loss during periods of high network traffic. For example, if a customer has a 10 Mbps data plan but the network can only deliver 5 Mbps during peak hours, the customer will experience reduced performance, which can be detrimental to their business operations.

Therefore, a CIR guarantee is a critical aspect of any service level agreement between a network service provider and its customers. It ensures that the customer can expect a certain level of service quality, which is critical for applications that require a reliable and consistent network performance, such as real-time applications, video conferencing, and cloud-based services.

How CIR is Calculated

CIR is typically specified as a minimum guaranteed bandwidth in bits per second (bps) or kilobits per second (Kbps). For example, a CIR of 1 Mbps means that the network service provider must deliver at least 1 Mbps of bandwidth to the customer at all times, regardless of network congestion or other factors.

The CIR value is usually determined based on the customer's bandwidth requirements and the network's capacity. For example, if a customer requires a 10 Mbps data plan and the network has a capacity of 100 Mbps, the CIR can be set at 10% of the network capacity, or 10 Mbps.

However, the CIR value may be adjusted based on the network's congestion levels and other factors that affect the network performance. For example, during periods of high network traffic, the network service provider may prioritize traffic based on its QoS requirements, which can affect the CIR for different types of traffic.

Applications of CIR in Different Types of Networks

CIR is used in different types of networks to ensure a certain level of service quality for data traffic. Some of the applications of CIR in different types of networks are discussed below.

Local Area Networks (LANs)

In a LAN, CIR can be used to ensure that each user or device on the network has a certain minimum guaranteed bandwidth. For example, in a business environment, the network administrator may set a CIR of 1 Mbps for each user, which ensures that each user can access the network resources at a certain minimum speed.

Wide Area Networks (WANs)

In a WAN, CIR can be used to ensure that each customer or site has a certain minimum guaranteed bandwidth. For example, in a multi-site organization, the network service provider may set a CIR of 10 Mbps for each site, which ensures that each site can access the network resources at a certain minimum speed, regardless of the network traffic levels.

Internet Service Providers (ISPs)

In an ISP network, CIR can be used to ensure that each customer has a certain minimum guaranteed bandwidth. For example, in a residential internet service, the ISP may set a CIR of 25 Mbps for each customer, which ensures that each customer can access the internet at a certain minimum speed, even during peak hours.

Cloud Service Providers

In a cloud service provider network, CIR can be used to ensure that each customer has a certain minimum guaranteed bandwidth for accessing the cloud resources. For example, a cloud storage provider may set a CIR of 100 Mbps for each customer, which ensures that each customer can upload and download data from the cloud at a certain minimum speed.

Limitations of CIR

While CIR is an important performance parameter in telecommunications networks, it has some limitations that network designers and service providers should be aware of. Some of the limitations of CIR are discussed below.

Network Congestion

CIR guarantees a minimum level of bandwidth, but it does not guarantee that the network will not be congested. During periods of high network traffic, the network performance may still be affected, even if the CIR is met. Therefore, network designers and service providers should consider other performance parameters, such as latency and packet loss, when designing the network and setting SLAs.

Network Capacity

CIR is determined based on the network capacity and the customer's bandwidth requirements. However, if the network capacity is not sufficient to meet the customer's requirements, the CIR guarantee may not be met. Therefore, network designers and service providers should ensure that the network capacity is sufficient to meet the customer's requirements, especially during periods of high network traffic.

Service Level Agreements (SLAs)

CIR is typically specified in service level agreements (SLAs) between the network service provider and the customer. However, the SLA may not be enforceable if the customer does not have a way to monitor the network performance and report any issues to the service provider. Therefore, service providers should provide customers with tools and resources to monitor their network performance and report any issues in a timely manner.

Conclusion

Committed Information Rate (CIR) is a critical service level agreement (SLA) parameter used in telecommunications networks to ensure a certain level of service quality for data traffic. CIR guarantees a minimum level of bandwidth that a network service provider must deliver to a customer at all times, regardless of network congestion or other factors that may affect the network performance. CIR is used in different types of networks, such as LANs, WANs, ISPs, and cloud service providers, to ensure a certain minimum level of service quality. However, CIR has some limitations, such as network congestion, network capacity, and enforceability of SLAs, that network designers and service providers should be aware of.