EIR (excess information rate)

The Excess Information Rate (EIR) is a term used in the context of digital telecommunications, particularly in the realm of packet-switched networks. EIR is a measure of the amount of data that is transmitted over a network in excess of the committed information rate (CIR). In simpler terms, EIR is the amount of "extra" data that can be transmitted over a network beyond what the user has contracted for.

To understand EIR, it is necessary to first understand the concept of CIR. CIR is the guaranteed amount of bandwidth that a network provider promises to provide to its customers. This is the minimum bandwidth that the customer is entitled to receive, and it is typically specified in the service level agreement (SLA) between the customer and the provider. CIR is expressed in bits per second (bps) or in units of data transfer per unit time, such as kilobits per second (kbps) or megabits per second (Mbps).

The purpose of CIR is to ensure that the customer receives a minimum level of service, even when the network is congested. When there is more demand for bandwidth than the network can handle, the network will prioritize traffic based on the agreed-upon CIR, and users who have contracted for a higher CIR will receive priority treatment. This means that if a user has contracted for a CIR of 10 Mbps, they will receive at least 10 Mbps of bandwidth, even if the network is congested and other users are experiencing slower speeds.

EIR, on the other hand, is the amount of bandwidth that is available to a user beyond their contracted CIR. EIR is typically expressed as a percentage of the CIR, and it represents the amount of "extra" bandwidth that is available to the user in times of network congestion. For example, if a user has contracted for a CIR of 10 Mbps and an EIR of 50%, they will receive at least 10 Mbps of bandwidth under normal conditions, but they may receive up to an additional 5 Mbps (50% of their CIR) during periods of network congestion.

The purpose of EIR is to provide users with additional bandwidth when it is available, without requiring them to pay for a higher CIR. This allows users to take advantage of unused bandwidth on the network, while still receiving the guaranteed minimum level of service that they have contracted for. EIR is often used in situations where there is a variable amount of demand for bandwidth, such as in internet service provider (ISP) networks, where users may have differing levels of demand for bandwidth at different times of day.

EIR can be implemented in different ways depending on the network technology being used. In some cases, EIR may be implemented using a token bucket algorithm, which allows users to transmit data at a rate up to their contracted CIR, but also allows them to "burst" data at a higher rate if there is unused bandwidth available on the network. In other cases, EIR may be implemented using a leaky bucket algorithm, which allows users to transmit data at a fixed rate up to their contracted CIR, but also allows them to send bursts of data if there is unused bandwidth available.

One of the challenges with implementing EIR is that it can lead to network congestion if too many users attempt to transmit data at the same time. This can cause delays and dropped packets, which can degrade the quality of service for all users on the network. To mitigate this risk, network providers may implement various techniques to manage congestion, such as traffic shaping, packet prioritization, and admission control.

In conclusion, EIR is a measure of the amount of data that can be transmitted over a network in excess of the contracted CIR. It allows users to take advantage of unused bandwidth on the network without requiring them to pay for a higher CIR, while still receiving the guaranteed minimum level of service that they have contracted for. EIR is often used in situations where there is a variable amount of demand for bandwidth, such as in ISP networks, and can be implemented using various algorithms and techniques to manage network congestion.

EIR is a useful tool for network providers and users alike, as it allows for more efficient use of available bandwidth and provides users with additional flexibility in their network usage. However, it is important for network providers to carefully manage the implementation of EIR to ensure that it does not lead to network congestion or a degradation of service quality for all users on the network.

In addition, it is important for users to understand their contracted CIR and EIR, as well as any associated SLAs, to ensure that they are receiving the level of service that they require for their network usage needs. Users should also be aware of any limitations or restrictions on their usage, such as data caps or fair usage policies, to avoid any unexpected charges or service disruptions.