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Building fast.com

techblog.netflix.com

71–80 of 180 posts

Re: Building fast.com

#71
Looks like I've hit a case of IPv4 vs. IPv6. I recently noticed that fast.com starting showing me at about half my connection speed, 50Mbps. I only just now realised while looking at the traffic that it was doing it over IPv6. Disabling IPv6 in my network gets me a reported speed of 120Mbps on fast.com, which sounds about right for a 100/100 subscription + some burst.

My ISP hasn't even officially announced any IPv6 support, I discovered more or less by accident that if I enabled 6rd things "just worked" so the fact that it might not go at the full speed of my subscription isn't something I'm super worried about.

I've actually got a similar issue with Google. While using IPv4 I don't even leave my ISP's network as they have those Google Global Cache boxes at the edge and terminate my connection there but over IPv6 I do go all the way out over the internet to Google.

Re: Building fast.com

#72
post #21

I seem to be unable to view the blog post in Firefox, it automatically goes to https which doesn't load. Maybe netflix messed up their HSTS settings at some point in the past?

Are you using HTTPS Everywhere? The Netflix blog post defaults to http for me. If I manually change to https, then it fails to load, as you describe.

No, I don't have it installed. But by testing addons, I figured out that Noscript is causing it.

It's weird because in its settings, there is nothing in the "force https website" list, and the "forbid http" section is set to never.

Re: Building fast.com

#73
post #60

This is beautiful. By using Netflix's actual CDN and requesting actual video files over HTTP, they're preventing ISPs from whitelisting fast.com without also whitelisting Netflix itself. Of course there'll be a game of cat-and-mouse with DPI, but it's a super-neat way of making it much harder for the ISPs to misrepresent actual video download speed...

Yeah right. Just wait until a user visits fast.com and unthrottle their connection for 20 minutes.

I strongly suspect some ISPs already do that with speedtest.net.

Re: Building fast.com

#75
post #65
post #55

Earlier quoted context omitted.

> That presumes they aren't fully emulating streaming traffic to test speed. It's not really a presumption, it's the actual facts on the ground. The actual benchmark file is served over HTTPS from, but there are still multiple simple ways to distinguish the current speedtest testcase from normal streaming.

> The actual benchmark file is served over HTTPS from, but there are still multiple simple ways to distinguish the current speedtest testcase from normal streaming. Do you mind explaining the details you are aware of that lead you to think they are not emulating streaming traffic in at least some portion of their test (since they are testing multiple sessions and types of traffic)? I may have missed a portion of this…

Sure. One example is that someone doing a speedtest will have accessed fast.com before starting a download of video streams. This can be detected despite the the encryption, e.g. via looking at the SNI of the requests. It doesn't matter what the video stream looks like, since those separate TCP flows can be cross-correlated.

Re: Building fast.com

#77
post #5
post #2

1. When will someone build a tool like this and then open up the measurements data? A speed-measuring tool would be infinitely more useful if we could investigate the results beyond just our one device for one test. A question I really want to be able to answer: which ISP offers the fastest service in my area? fast.com and speedtest.net could easily answer this question if they made the data available. 2. I think tes…

Dslreports speedtest publishes the results publicly: http://speedtest.dslreports.com/

They appear to only publish it by ISP. Part of my problem is not knowing comprehensively what ISPs serve my area, so I need to look it up by zip code or city.

Re: Building fast.com

#78
post #2

1. When will someone build a tool like this and then open up the measurements data? A speed-measuring tool would be infinitely more useful if we could investigate the results beyond just our one device for one test. A question I really want to be able to answer: which ISP offers the fastest service in my area? fast.com and speedtest.net could easily answer this question if they made the data available. 2. I think tes…

Google / YouTube has a 'Video Quality Report' which will measure your speeds and will also show local ISPs speeds as well. https://www.google.com/get/videoqualityreport/

"Reports from your location are not available yet." Uh, I didn't tell you my location, Google... what the heck?

Re: Building fast.com

#79
post #70
post #53

I see this as a tool for netflix to immediately raise concerns about ISP neutrality. The link to another speed test (using some minor server) is there not by chance. If speed test is far better than netflix fast.com the ISP is clearly limiting the customer.

I wish that my ISP (Comcast) would throttle Netflix in the evening. My internet bandwidth gets reduced to 200 kbps during prime time (roughly 9 to 11 PM). It makes it challenging to work, especially if I need to stay connected to a VPN.

If you were wishing, why not wish for your ISP to aptly judge its peek traffic and scale its infrastructure?
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