As most of us are aware, one of NetFlow’s primary intended uses was for network traffic billing. Although it is largely used for network traffic analysis and baselines, I thought I would take this opportunity to point out how it can be used by service providers interested in our NetFlow billing module.
First of all, it is important to understand how 95th percentile for burstable billing is calculated. When I first heard the term “95th percentile” I immediately started thinking of the statistics and probability classes I took in graduate school. However, confidence intervals and normal curves have different applications and may not be ideal for bandwidth billing.
History on Service Providers and Bandwidth
Why do service providers resell more bandwidth than they lease? To answer this question, we need to understand that service providers buy WAN bandwidth from other service providers. They then resell portions of the bandwidth to other consumers. If the service provider leases 3 gigabits worth of bandwidth for example and each customer gets a 1 megabit connection to the internet, you might think that they could only have 3000 customers. As most of you are aware, this is not the case. Service providers may have tens of thousands of customers using the same pipe. How?
Service providers know that most consumers don’t use the entire amount of bandwidth they purchase. For example: for most of us, our connection at home goes largely unused during business hours because we are at work. Because of this, the service provider will resell the same bandwidth to businesses who will use it during the day but, less at night. Even at night when we do get on-line, many of us aren’t downloading lots of data (unless you have teenagers). With bandwidth to spare, service providers try to keep adding more customers to share the pipe.
As additional customers are brought on, service providers carefully monitor how much of the total bandwidth is used by their customer base.
By using trends like the one above from Denika Performance Trender, service providers can see if they can bring on more customers before buying more bandwidth.
In part two of this blog I will cover why Service Providers need 95th Percentile.