At Cedexis, we often talk about our Radar community and the vast number of Real User Measurements (RUM) we take daily. Billions every day. Is that enough? Too many? How many measurements are sufficient? These are valid questions. As with many questions, the answer is “it depends”. It depends on what you are doing with the RUM measurements. Many companies that deploy RUM use it to analyze a website’s performance using Navigation Timing and Resource Timing. Cedexis does this, too, with its Impact Product. To do this type of analysis may not require billions of measurements a day.
However, making the RUM data actionable by utilizing the data for Global Traffic Management is another matter. To do this, it is incredibly important to have data from as many of the networks that make up the Internet as is possible. If the objective is to have a strong representative sample of the “last mile” then it turns out you need a pretty large number. Let’s take a closer look at perhaps how many.
The Internet is a network of networks. There are around 51k networks established that make up what we call the Internet today. These networks are named, or at least numbered, by a designator called an ASN, or Autonomous System Number. Each ASN is really a set of unified routing policies. As our friend Wikipedia states:
“Within the Internet, an autonomous system (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators on behalf of a single administrative entity or domain that presents a common, clearly defined routing policy to the Internet.”
Every ISP has one or more ASNs – usually more. There are 51,468 ASNs in the world as of August 2015. How does that look when you distribute it over whatever number of RUM measurements you can obtain? A perfect monitoring solution should tell you, for each network, whether your users are experiencing something bad – for instance, high latency from the network they are using.
If you are able to spread the measurements out to cover each network evenly (which you cannot) then you get something like the graph below.

On the left hand column, you see the number of RUM measurements you get a day and the labels on the bars show the number of measurements PER networks you can expect.
So, if you distributed your RUM measurements over all the networks in the world, and you only had a 100,000 page visits a day, you would get two measurements per network per day. This is abysmal from a monitoring perspective.
With so many ASNs, it’s easy to see why using synthetic measurements is hopeless. Even if you were to have 200 locations for your synthetic measurements and three networks per location that would only give you 600 ASN/Geo map pairings. Cedexis dynamically monitors over seven million ASN/Geo maps every day.
One issue, however, is that RUM measurements are not distributed equally. We have been assuming that given your 51k networks you can spread those measurements over them equally, but that’s not the way RUM works. Rather, RUM works by taking the measurements from where they actually come from. It turns out that any given site has a more limited view of the ASNs we have been discussing. To understand this better, let’s look at a real example.
Assume you have a site that generates over 130 million page views a day. The data is from a Cedexis client and was culled over a 24-hour period in October 2015.
134 million is a pretty good number, and you’re a smart technologist who implemented your own RUM tag – you are tracking information about your users, so you can improve the site. You also use your RUM to monitor your site for availability. Your site has significant users in Europe and North and South America, so you’re only really tracking the RUM data from those locations for now. So, what is the spread of where your measurements come from?
Of the roughly 51k ASNs in the world, your site can expect measurements from approximately 1,800 different networks on any given day (specifically 1,810 on this day for this site).

In the diagram above, you see a breakdown of the ISPs and ASNs that participated in the monitoring on this day – the size of the circle shows the number of measurements per minute. At the high-end are Comcast and Orange S.A. with over 4,457 and 6,377 measurements per minute, respectively. The last 108 networks (with the least measurements) all garnered less than one measurement every two minutes. Again, that’s with 134 million page views a day.
The disparity between the top measurement-producing networks and the bottom is very high. As you can see in the table below, almost 30% of your measurements come from only 10 networks while the bottom 1,000 networks produce 2% of the measurements.

What is the moral here? Basically, RUM obtains measurements from the networks where the people are and not so much from networks where there are fewer folks. And, every site has a different demographic, meaning that the networks that users come from for Site A is not necessarily the same mix of networks for Site B. Any one site that deploys a RUM tag will not be able to get enough measurements from enough networks to make an intelligent decision about how to route traffic. It just will not have enough data.
This is value of the Cedexis Radar community. By taking measurements from many sites (over 800 and rising) the Cedexis Radar community is able to combine these measurements and get a complete map of how ALL the ASN/GEO pairings are performing – over seven million ASN/GEO pairings a day – and our clients can utilize this shared data for their route optimization using Cedexis Openmix. This is what we mean when we say “Making the Internet Better for Everyone, By Everyone”. The community measurements allow every individual site (that may only see 1,800 of the 51k networks) to actually see them all!
The Radar community is free and open to anyone. If you are not already a member, we urge you to sign up for a free account and see the most complete view of the Internet available today. While you are at it, you can go check out Radar Live, our live view of Internet traffic outages in real time.