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Committed Information Rate (CIR) Explained

Every company has unique bandwidth needs when it comes to the Internet so a one-price-fits-all solution certainly would not work.

Every company has unique bandwidth needs when it comes to the Internet so a one-price-fits-all solution certainly would not work. Fortunately, Internet service providers (ISPs) such as PS Lightwave can offer service plans based on a committed information rate (CIR).

A CIR guarantees a customer a certain bandwidth or network data usage that will be available 100 percent of the time.

In frame relay networks, where multiple customers can share the same physical network, ISPs will guarantee that each customers’ connection will always support their CIR rate. This bandwidth rate is typically expressed in bits per second.

“When we provide a service, a customer always signs up for a CIR – that is a committed information rate – it’s the bandwidth that we allocate for the customer and for the service. It’s bandwidth we guarantee to be available for the customer service,” explained PS Lightwave’s Director of Network Operations Swen Wulf.

Different ISPs define and package CIRs differently, but the bottom line is that CIRs allow for customers to simultaneously share networks with varying bandwidth plans.

History of Committed Information Rates (CIRs)

CIRs were born of necessity when frame relay networks in the 1990s needed to devise customer usage and pricing plans. One of the earlier mentions of CIR, according to, is from June 14, 1994 in a column of The Age from Melbourne, Australia by systems engineer Scott Petty of Com Tech Communications.

Petty was covering the alliance announcement of AT&T and Novell creating the public data network called NetWare Connect Services, an early public data backbone network that supported TCP/IP.

While we can credit Petty with forward-thinking, we must also point out that he had a swing-and-a-miss when he wrote that, “While valuable, the Internet hasn’t yet (and may never) fully evolve to support commercial applications.”

A lot has changed in the 21 years since, but frame relay service is still not sold according to list prices, but usually the price is negotiated per customer based on CIR.

When You Need More Bandwidth: “Burst Ability”

While most ISPs utilize CIRs in their service plans not all of them give customers the availability to exceed their contracted data rate. “We also allow our customers to burst above that CIR. We are unique in that space that we allow “burst ability” of our services,” said PS Lightgwave’s Wulf.

This allows PS Lightwave customers, if they have a large event or need to download a large patch, to go beyond or burst above their CIR. Wulf says that in most cases, PS Lightwave customers can burst up to port speeds, which are the maximum speed rate supported by a physical port.

“We look at all of our links and look at the usage to ensure that we have ample bandwidth reserves available to provide (burst) service,” said Wulf.

95th Percentile Rule Prevents Billing Surprises

While some ISP customers do not want the option to burst above their CIR, thus eliminating any chances of overage charges, that does not allow for flexibility. “Certainly, we can limit and take away the “burst ability” but we find that most customers really enjoy being able to burst their CIR up to port speed to accommodate for large events, big downloads that happen infrequently,” said PS Lightwave’s Wulf.

The good news for those customers that do need to burst their CIR is that PS Lightwave bills according to the 95th Percentile Rule which can help prevent billing surprises.

“The burst ability comes with a price. We employ something which is called the 95th Percentile Rule,” Wulf sad. “It’s a way of billing for overages when customers go over their CIR.”

Wulf explained the 95th Percentile Rule process: “What we do is look at a port and we extract the counters of the usage. We do this every five minutes and we do this the whole month long. So, we have a bucket with the usage in five-minute intervals for the whole month. We sort this bucket from high to low and kick away (the highest) five percent – that’s the 95 percentile rule.”

Customers are provided a portal where they can monitor their bandwidth usage, including their current 95th Percentile level and its level according to their CIR. Overages are only charged when their 95th Percentile usage exceeds CIR for the month.

Contact PSLightwave today to find out how our Internet offerings can support every Houston-area organization’s needs, from bandwidth ranging from 10 megs to over 40G.

PS LIGHTWAVE provides high-speed, fiber Internet for public and private commercial entities in the Greater Houston and surrounding areas.

Through our high-quality infrastructure, innovative technology and expert, locally based support, we deliver not only the best in connectivity and reliability but in scalability and redundancy. We invite you to learn more about our services, our history and our dedicated team.

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PS LIGHTWAVE, a leading telecommunications service provider headquartered in Houston, Texas, provides managed Ethernet Data Circuits, Internet, private network solutions and Voice over IP (VoIP) over one of the nation’s largest facilities-based private Metropolitan Area Networks (MANs). The switched Layer 2 network, backed by 24/7/365 Network Operations Center (NOC) support, encompasses approximately 5,500 route miles and 1,400 on-net locations and connects 100+ fault-tolerant multi-gigabit Ethernet rings for built-in redundancy, security, low latency, and high-availability. At PS LIGHTWAVE Great Connections Happen Here™.

For more information, please visit or call 832-615-8000.