Deep-dive into Cloudflare’s Speed Test

There are lot of web apps available to test your home internet connection. Your ISP will have their own tool, I use fast.com from Netflix and Netgear Genie to make sure I am connected to Internet or not. Couple weeks ago Cloudflare has released its home grown solution to test the home internet connection called Speed Test. You can access it from https://speed.cloudflare.com/ This blog post will deep-dive into Cloudflare’s Speed Test.

Why another speed test app?

As I mentioned earlier, there are hundreds of web apps and mobile apps available to test the internet connection. But why Cloudflare has to (re)create again. I believe Cloudflare is the new Google. Here is the excerpt from Cloudflare:

Although there are a slew of speed testing tools out there, none of them give you precise insights into how they came to those measurements and how they map to real-world performance. With speed.cloudflare.com, we give you insights into what we’re measuring and how exactly we calculate the scores for your network connection.

Cloudflare’s speed test doesn’t have a fancy domain name like fast.com. It is hosted under sub-domain of cloudflare.com.

How to get started?

Unlike other web or mobile app, there is no start button in Speed Test (let’s call Speed Test). E.g. Speedtest.net has a GO button, if a user want to start the test, they can simply click on that button.

After visiting https://speed.cloudflare.com/, your test will start immediately. After all the tests are completed, you can see the results instantly.

Deep-dive into Cloudflare's Speed Test
Deep-dive into Cloudflare’s Speed Test

Speed Test displays key metrics such as Download speed, Latency, and Jitter in the main dashboard. Detailed measurements will get displayed just beneath the main dashboard. Server Location will get displayed in the right pane as shown above.

Privacy Policy

As mentioned in the Cloudflare Privacy Policy, they do not sell your data. Performance data is collected, anonymized and is governed by the terms of Cloudflare. For more details you can refer this link https://www.cloudflare.com/privacypolicy/

Let’s talk performance

After you launch the Speed Test, it will connect you to the nearest data center. You can see the map in the right pane as shown below. My closest data center is Chicago as shown below.

Server Location
Server Location

If you zoom in to the Cloudflare data center, it will not reveal the exact location of data center, instead it will display the airport location. It uses Anycast network (from Cloudflare) to detect the nearest data center.

Server Location using IATA code
Server Location using IATA code

After connecting to the nearest data center, Latency and Jitter test will kick off.

Latency will be measured using 20 iterations and the median will be considered. Lower the number better the performance. Latency is nothing but time to first byte from browser perspective.

Measurements and Chart representation
Measurements and Chart representation
  1. Each dot represents the individual measurement
  2. Rectangle represents the measurements from 25th percentile to 75th percentile
  3. Solid line inside the rectangle represents the median
  4. Dotted line represents average.

Here is the zoomed in image.

Latency Measurement Chart
Latency Measurement Chart

Here is the definition of Jitter. Lower the number is better.

Jitter
Jitter

After Latency and Jitter measurement, the app will start downloading small files starting from 10kB and it reaches the threshold based on the performance.

Important Note:

As mentioned above, the app will first connect to the data center and runs latency and jitter tests and then it will kick off the download tests. But this will cause Bufferbloat. This issue has been raised in Cloudflare GitHub repository by Toke Høiland-Jørgensen https://github.com/tohojo. Here is the issue id.

The suggestion from Toke is to continue the latency tests during the download tests. This suggestion will improve the metrics and performance.

As you see my network performance, it was able to reach till 25 MB download test. More the file size, lesser the number of iterations. If your network performance is poor, you may not be able to reach for 10MB download test.

Download Measurements
Download Measurements
  • 10kB has 10 iterations
  • 100kB has 10 iterations
  • 1MB has 8 iterations
  • 10MB has 5 iterations
  • 25MB has 3 iterations

Interesting Facts

  • Max file size that you can reach is 100MB :)
  • If you open the file which Speed Test is downloading is nothing but string of zeroes and some random string at the end.

If you click on the chart, you can see the detailed metrics.

Raw Data
Raw Data

For the final download internet speed, it will calculate the overall 90th percentile. You can also download the metrics by clicking on Download button as shown below.

Download Results
Download Results

Here is my raw data:

time Formatted Timestamp direction bytes latency bps Formatted Mbps ttfb duration responseSize
1591643367414 8:09:27 PM download 0 30.13502098 5492134.678 5.492134678 152.135 0.890000025 1611
1591643368111 8:09:28 PM download 100000 31.51511296 174902506.4 174.9025064 49.51499996 4.585000046 101241
1591643368748 8:09:29 PM download 0 27.91007098 5489820.271 5.489820271 51.90999998 0.835000013 1573
1591643370080 8:09:30 PM download 0 33.08994298 1062008.745 1.062008745 98.08999998 1.144999987 1152
1591643370386 8:09:30 PM download 0 29.075071 1460869.656 1.460869656 53.075 0.689999957 1126
1591643370590 8:09:31 PM download 0 32.26987401 1231515.158 1.231515158 50.27000001 0.824999996 1127
1591643370919 8:09:31 PM download 0 30.24003999 1651612.887 1.651612887 47.23999999 0.620000006 1128
1591643371292 8:09:31 PM download 0 31.28508002 1296202.594 1.296202594 65.28500002 0.789999962 1128
1591643371527 8:09:32 PM download 0 29.82011304 5209091.213 5.209091213 47.82000004 0.879999949 1573
1591643371898 8:09:32 PM download 0 29.37009201 1228571.438 1.228571438 50.37000001 0.839999993 1129
1591643372098 8:09:32 PM download 0 48.58994699 1385234.85 1.38523485 67.58999999 0.745000027 1129
1591643372255 8:09:32 PM download 0 26.69980204 1664516.112 1.664516112 43.70000004 0.620000006 1129
1591643372376 8:09:32 PM download 0 28.50486301 905263.1519 0.905263152 59.50500001 1.140000008 1129
1591643372487 8:09:32 PM download 0 31.49487398 5942856.816 5.942856816 49.49499998 0.770000042 1572
1591643372584 8:09:33 PM download 0 28.88513399 1563636.455 1.563636455 43.88499999 0.659999961 1129
1591643372667 8:09:33 PM download 0 32.67480202 1155555.538 1.155555538 49.67500002 0.720000011 1104
1591643372750 8:09:33 PM download 0 29.80004001 1011764.739 1.011764739 46.80000001 1.019999967 1129
1591643372870 8:09:33 PM download 0 29.14511296 1885271.254 1.885271254 47.14499996 0.645000022 1152
1591643373006 8:09:33 PM download 0 56.45492601 443290.0412 0.443290041 78.45500001 2.310000011 1128
1591643373102 8:09:33 PM download 0 28.10509204 6366667.085 6.366667085 49.10500004 0.719999953 1573
1591643373174 8:09:33 PM download 0 27.77011297 1220740.709 1.220740709 45.76999997 0.675000018 1103
1591643373272 8:09:33 PM download 10000 30.41511297 102460756.9 102.4607569 48.41499997 0.79000002 11118
1591643373682 8:09:34 PM download 10000 39.750206 66472129.26 66.47212926 55.75 1.220000035 11137
1591643373853 8:09:34 PM download 10000 41.03020603 105756870.2 105.7568702 57.03000003 0.764999946 11113
1591643373969 8:09:34 PM download 10000 33.92511102 111856553.1 111.8565531 74.92500002 0.724999991 11137
1591643374053 8:09:34 PM download 10000 28.50004001 82552194.72 82.55219472 45.50000001 1.025000005 11577
1591643374144 8:09:34 PM download 10000 28.56506101 116684892.9 116.6848929 42.56500001 0.694999995 11137
1591643374277 8:09:34 PM download 10000 38.88990298 102713921.4 102.7139214 86.88999998 0.79000002 11143
1591643374407 8:09:34 PM download 10000 38.11016402 82759187.61 82.75918761 60.11000002 0.979999953 11138
1591643374531 8:09:35 PM download 10000 32.61020398 111090406.6 111.0904066 71.60999998 0.730000029 11137
1591643374620 8:09:35 PM download 10000 31.30987403 114208451.8 114.2084518 49.31000003 0.709999993 11136
1591643374731 8:09:35 PM download 100000 30.39518498 165389732.9 165.3897329 49.39499998 4.870000004 101681
1591643375035 8:09:35 PM download 100000 51.87004002 138888312.4 138.8883124 68.87000002 5.774999969 101260
1591643375157 8:09:35 PM download 100000 40.05478101 98209430.42 98.20943042 60.05500001 8.165000007 101235
1591643375320 8:09:35 PM download 100000 30.74004001 113958208.7 113.9582087 47.74000001 7.035000017 101212
1591643375436 8:09:35 PM download 100000 29.59521598 101120806.8 101.1208068 55.59499998 7.930000022 101236
1591643375522 8:09:36 PM download 100000 32.359998 194393210.4 194.3932104 55.36 4.125000036 101234
1591643375644 8:09:36 PM download 100000 34.385278 68490476.06 68.49047606 51.385 11.76000002 101681
1591643375757 8:09:36 PM download 100000 60.48020599 149920000.2 149.9200002 76.47999999 5.349999992 101259
1591643375855 8:09:36 PM download 100000 29.11989504 134430847.5 134.4308475 44.12000004 5.96499996 101235
1591643376033 8:09:36 PM download 1000000 51.000061 103707593.7 103.7075937 65 77.23499998 1002232
1591643376253 8:09:36 PM download 1000000 37.56491398 82013085.54 82.01308554 72.56499998 97.66500001 1002226
1591643376434 8:09:36 PM download 1000000 34.27996802 97937372.39 97.93737239 50.28000002 81.78499999 1002226
1591643376640 8:09:37 PM download 1000000 33.57990501 69885387.87 69.88538787 58.58000001 114.665 1002676
1591643376846 8:09:37 PM download 1000000 36.30009199 93192321.14 93.19232114 57.29999999 85.94999998 1002235
1591643377023 8:09:37 PM download 1000000 29.92496798 102189436.1 102.1894361 45.92499998 78.38000002 1002201
1591643377213 8:09:37 PM download 1000000 38.399832 114295890.4 114.2958904 62.4 70.08000003 1002232
1591643377378 8:09:37 PM download 1000000 34.02996798 126017621.1 126.0176211 50.02999998 63.56000004 1002210
1591643378017 8:09:38 PM download 10000000 36.27003796 155131678.5 155.1316785 76.26999996 516.265 10012132
1591643378707 8:09:39 PM download 10000000 39.07500797 138248324 138.248324 72.07499997 579.34 10012598
1591643379435 8:09:39 PM download 10000000 33.78005901 132977885.5 132.9778855 70.78000001 602.275 10012157
1591643380149 8:09:40 PM download 10000000 32.380059 136674065 136.674065 69.38 585.985 10012119
1591643380826 8:09:41 PM download 10000000 54.29975799 153141530.7 153.1415307 100.3 522.975 10012149
1591643382446 8:09:42 PM download 25000000 29.70008799 140018808.9 140.0188089 96.69999999 1429.96 25028662
1591643383906 8:09:44 PM download 25000000 39.27496201 162604349.7 162.6043497 124.275 1231.34 25028655
1591643385432 8:09:45 PM download 25000000 29.27995203 160793569.1 160.7935691 104.28 1245.23 25029122

90th percentile formula is =PERCENTILE.EXC(G2:G57,0.9). Column G should have the speed in Mbps.

CSV Data
CSV Data

After your test is done, you can retest it. During the test you can pause the test.

Upload Speed Test

Upload Speed test has been temporarily turned off by Cloudflare due to some incorrect measurements.

Note: we’ve temporarily disabled upload testing while we investigate reports of incorrect upload speed reports on very fast connections.

From Cloudlfare blog

Network Trace

Here is the captured HTTP requests from developer tools in Edge.

Network Trace
Network Trace
  • 170 HTTP requests
  • ~30 seconds to finish the test
  • ~68 MB resources
  • ~61 MB transferred

Tech Stack

Speed Test is the open source project in GitHub.

Pros

I ran multiple tests in Speed Test. It is one of the best tool to measure the performance.

  • Its light weight
  • Results download in CSV format
  • Intuitive user interface
  • Neat graphs and insights about measurements
  • Responsive web app
  • Open source

Cons

  • You cannot change the server location
  • Still the measurement needs more accuracy
  • No start button

Conclusion

Cloudflare’s Speed Test is very light weight web app to measure the performance of your home network. It is fast and the results are intuitive. As of now, no upload tests and the accuracy can be improved while enabling latency measurement during download tests.

What is your favorite app to measure your internet performance? Please let me know in the comments.

Deep-dive into Cloudflare's Speed Test

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