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editfmah
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File download speed on 200Mbps connection

I have had my 200 Mbps connection for a few months now, and largely i'm very happy with it (compared to my 1.76 Mbps connection from BT beforehand), however I never seem to be able to actually achieve this figure in real world tests.

My network is entirely up to scratch so I know it is not that, but to be clear.  I am wired, and I have real world through put to any of my machines, to the router at no less than 330 Mbps, getting file transfer speeds across the distance of 27 MB/s from one computer to another.

Speed tests always come back fine, see below:

Screen Shot 2016-04-22 at 01.17.49.png

And it is the same for all the major ones.  But my real world throughput is very poor.  I seem to get around 680 KB/s to about 1.8 MB/s, far short of the 20 MB/s I should be able to achieve if conditions are perfect.

Services, such as Netflix, that rely on CDN's seem to fair better and I see spikes of 70 Mbps.  But when ever i've actually needed to ship large files and data around, it slows right down.

Now, i've picked a few tests, from sites with huge capacities:  FreeBSD ISO images from mirror.ox.ac.uk which has multiple redundant 10GbE uplinks and also berkley, which is on one of the fastest connections on the planet. This is pretty much the common result:

Screen Shot 2016-04-22 at 01.12.40.pngScreen Shot 2016-04-22 at 01.16.43.png

As you can see, it's the same old speed over and over.  Yet I get 207.1 MB/s, 30 seconds later from exactly the same URL (but obviously I don't know if it's the same server, but it is entirely repeatable) when l remotely log into our office network and retrieve the same file on the office 1Gbps connection at the weekend.

So I decided to try and download a large file from the Amazon cloudfront CDN, this faired very poorly, despite being in the EU availability region.

Screen Shot 2016-04-21 at 19.44.40.png

Which, on a server in the office was able to download 5x the speed.

My neighbour helped out with his BT infinity connection, and wirelessly through a wall, My laptop was able to download 5 minutes earlier from the mirror.ox.ac.uk site at 3.5 MB/s.

Screen Shot 2016-05-17 at 11.05.41.png

 

But the exception that proves the rule is that I can transfer a file, using SCP/SSH from a server at work at full speed, 19.4 MB/s.  Proving that the connection is capable, but the actual throughput I can achieve form the internet is very lacking.  OS updates is another sticking point as there are very slow, on what should be an amazing connection. 

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watercooled
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Re: File download speed on 200Mbps connection

Out of interest, you could do a couple of traceroutes and see if there's any link between affected/unaffected connetcions.

For example, I've found a couple of CDNs which seem far less severely affected, Cachefly (e.g. twit.tv podcast videos) and whoever Virtualbox use for their downloads.

Judging by hostnames, neither of those routes seem to go via certain interconnetcion points in London (things like tele-ic, teln-ic, tcma-ic, tcl5-ic, linx, telw-ic (you get the picture) as part of the hostname) so it does seem route-dependent. I'm guessing your fast work-based SSH server doesn't take that route either?

I'm stuck with the same 1,000-odd KB/s download speed from the vast majority of servers with a single thread.

Try the Thinkbroadband speed test as the speedtest.net one just bruteforces its way through congestion by using tons of DL threads - I've seen it use upwards of 25 threads. The TBB one shows you single and 6 thread results and will flag it as a problem if there's a large difference between the two. http://www.thinkbroadband.com/speedtest.html


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cje85
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Re: File download speed on 200Mbps connection

Poor single thread download speeds seem to be an increasing problem. There is a long post about this issue at http://community.virginmedia.com/t5/Speed/Very-poor-HTTP-download-speed/td-p/3026879 but unfortunately there is no solution, even after 5 months.

One customer logged an official complaint and received a call back from Virgin Media, who claimed that it isn't a fault and is just how the network will operate from now on (see this message) however one of the forum admins believes it is a fault which is still being investigated....so it may or may not get fixed depending on who's correct.

 

 

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editfmah
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Re: File download speed on 200Mbps connection

Thanks for the info, I will additionally add a couple more points.

1). It seems to happen at all times of the day
2). It does not improve if I use a VPN, therefore tunneling the data over another protocol. So I assume this is also rate limited in the same way.
3). Although I have not made accurate measurements, it does look like the speeds half when two downloads are simultaneous (given long enough to even out).

If this is how the network will operate from now on, then I will happily spend some money breaking my contract or getting my package reduced to 50mb which is all I seem to be able to max out at in the real world anyway.
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editfmah
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Re: File download speed on 200Mbps connection

Ah, I have now read that thread.  And yeah, VM isn't going to work for me.  I was already a bit unsure because of the upload speed vs BT, but I figured that the download speed would more than make up for any slight inconvenience that having to wait for a few GB to upload might impose.

I guess now I have to try and cancel, and when they won't let me i'll try and abuse my bank provided solicitors.

I was hoping this was going to be a happy relationship for all involved, but i'd best give them a chance to at least respond, but it seems futile and i'm not big on wasting my own time.

Thanks @cje85 for the links.

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watercooled
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Re: File download speed on 200Mbps connection

Out of interest, you could do a couple of traceroutes and see if there's any link between affected/unaffected connetcions.

For example, I've found a couple of CDNs which seem far less severely affected, Cachefly (e.g. twit.tv podcast videos) and whoever Virtualbox use for their downloads.

Judging by hostnames, neither of those routes seem to go via certain interconnetcion points in London (things like tele-ic, teln-ic, tcma-ic, tcl5-ic, linx, telw-ic (you get the picture) as part of the hostname) so it does seem route-dependent. I'm guessing your fast work-based SSH server doesn't take that route either?

I'm stuck with the same 1,000-odd KB/s download speed from the vast majority of servers with a single thread.

Try the Thinkbroadband speed test as the speedtest.net one just bruteforces its way through congestion by using tons of DL threads - I've seen it use upwards of 25 threads. The TBB one shows you single and 6 thread results and will flag it as a problem if there's a large difference between the two. http://www.thinkbroadband.com/speedtest.html

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editfmah
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Re: File download speed on 200Mbps connection

Hi, here is my result from that test.

Screen Shot 2016-05-17 at 20.01.39.png

Do you have any specific trace's you'd like me to run that would be specifically useful?

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editfmah
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Re: File download speed on 200Mbps connection

And here are some traceroute results: First to my office network, which is a 1Gbps connection on a 10Gbps bearer, and was able to transfer at full speed, but i've just tested it again, so I can get some evidence together, and once again i'm averaging only 1.3 MB/s. I've checked our router throughput and it is negligible at this moment.

Screen Shot 2016-05-17 at 20.25.58.png

I've searched around, and managed to find a SQL Express download from microsoft that I could get ~3.5 MB/s rate at.

Screen Shot 2016-05-17 at 20.58.57.png

And here is the traceroute:

Screen Shot 2016-05-17 at 21.02.31.png

Interesting where it ended up..... But then I imagine that the akamai CDN will peer with VM.

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watercooled
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Re: File download speed on 200Mbps connection

Just a couple to compare your affected/unaffected examples would be ideal, but I understand if you can't post results for the trace to your workplace. Also, make sure you get the IP/hostname for the actual CDN, not just the website as they're not always the same, though they are often the same for download mirrors.

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editfmah
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Re: File download speed on 200Mbps connection

I'm just comparing and diff'ing the routes to see if there is a pattern. 

 

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watercooled
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Re: File download speed on 200Mbps connection

Yeah sorry I started typing that before I saw your reply. One which is often fast for me is cachefly e.g. this video http://www.podtrac.com/pts/redirect.mp4/cdn.twit.tv/video/floss/floss0387/floss0387_h264m_1280x720_1...

Currently getting about 10MB/s but I'll get near the full 20-odd during off-peak hours. Either way it's a heck of a lot faster than the vast majority of download servers I've tried e.g. university of kent, goscomb, cdimage.ubuntu.com, etc - they're all perilously slow.

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