A customer reported page loads were exceeding 60-seconds; but they should have been 3-seconds or less.
Our site monitoring alerts didn't report a problem. Other customers online at the time didn't report a problem. Running our performance test battery didn't show a problem.
It was time to watch her reproduce the problem. We setup an online meeting and temporarily made her host. We observed her actual performance -- measuring it at 21 times slower than expected! Further testing revealed that she didn't have a problem from her home computer...
But why? Why just the corporate computers? Was it a faulty hardware? Was it machine configuration? Was it network configuration?
Next, we asked her to browse to http://www.speedtest.net/ and run the test.
We compared her test results against our baseline. Her latency (ping) was averaging 226ms...but the norm is around 35ms. Bingo! Latency was the culprit.
We soon discovered that this customer routed all corporate traffic through Atlanta. So, she was physically located 250 miles from us on the West Coast, but her traffic was routed 6,000 miles (round trip) across the U.S.
More hops and more switchgear to go through yielded larger latencies. A slow central proxy server in Atlanta also compounded the problem.
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Content Acceleration:
Latency is often just an exacerbating symptom, not the root issue. Excess server requests are more typically the cause of poor performance (poor page design, or large session state management, etc.). If you can’t re-code, then research “content acceleration” or “web acceleration” as a viable work-around for poor latency. Content acceleration reduces the number of hops by caching content around the world and using faster, more direct links (less switchgear = less latency). Content acceleration also compresses the content where possible._______________________________________________
What is Speedtest.net?
Speedtest.net is the best speed test sites out there, performing over 1 million tests per day from hundreds of servers dispersed throughout the world. They perform three key measurements to determine the overall quality and performance of your Internet connection: download speed, upload speed, and latency.
Latency or Ping is the time it takes in milliseconds for a small piece of data to be sent from your computer to the Internet and back – the more switch gear or extra indirect hops to pass thru, the slower the connection (think flow velocity inside the pipe).
• Expect 20-30ms for geographically close servers.
• Expect 80ms for cross-country traffic (5,000km / 3,075mi).
• Greater than 100ms is bad.
Download Speed is the rate at which data is sent down from the Internet to your computer (think diameter of the pipe feeding in).
• Dialup: Expect 0.4-2Mbps
• DSL: Expect 1-2Mbps for standard, and 3-7Mbps for premium
• Cable: Expect 1-6Mbps for standard, and 8-20Mbps for premium
Upload Speed is the speed at which data is sent up from your computer to the Internet (think diameter of the pipe feeding out). Upload speed is typically many times slower than download speed (except dialup where they are equal).
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(B) When you first enter the website, it checks your IP address to determine your approximate location on earth.
(C) Clicking the “Begin Test” button will run the test.
(D) Run results show the download rate, upload rate, and ping (latency).(E) Download speed estimates show how long a typical MP3 file or video clip takes to download on your network.
For a more detailed analysis of latency and related delay metrics, visit http://www.pingtest.net/.The site measures latency, jitter, and packet loss…and even includes a grade for your line. Here is a screenshot:
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Other Notes:
Speedtest.net Requirements:
• Web browser
• Javascript
• Flash 8 installed
Avoid Inaccurate Results:
While you are running your speed test, be sure...
• No other computers are online stealing bandwidth
• Your test computer is not busy doing anything else
• You are direct connected (not over wireless)
Benchmarks:
You can compare your performance against the World Results section to browse top bandwidth speed by country, or narrow down statistics to very specific locations and even specific ISP’s.
Other Great Speed Test Sites:
• Audit My PC:
http://www.auditmypc.com/internet-speed-test.asp
• CNET Speed Test:
http://reviews.cnet.com/internet-speed-test/
• ComCast Speed Test:
http://speedtest.comcast.net/
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