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Speedtest 17Mbit/s - what iPlayer speed can I expect?

PNRichardC
Dabbler
Posts: 14
Registered: 20-10-2014

Speedtest 17Mbit/s - what iPlayer speed can I expect?

The BT Wholesale speedtest is showing 17Mbit/s (it was19Mbit/s a few weeks ago).  My router is showing a downstream speed of 21222kbit/s with a noise margin of 4dB and 13dB attenuation and an upstream speed of 851kbit/s.
The maximum HD data rate of the BBC iPlayer is 2.8Mbit/s.  My line speed ought to be sufficient for 6 computers to stream the iPlayer simultaneously at the maximum HD data rate.  What actually happens if I try to watch live television is that it starts at 1470kbit/s.  After about 30 seconds it shows a rotating arrow for a minute or two.  It then starts again at 923kbit/s.  The speed then falls again to 501kbit/s and sometimes even 350kbit/s.  This happens at any time of the day, not just peak times.
I also have problems with web browsing, particularly on sites like dailymail.co.uk and independent.co.uk with large numbers of adverts.  It can sometimes take 5 minutes to load a page.  I have tried different DNS servers.  Changing DNS servers sometimes helps but I have not found any which provide a solution.
It may be that the Ealing exchange is hopelessly overloaded, but if it is why does Plusnet or BT not add more capacity?
I have seen criticism of PlusNet on other forums for restricting speeds to avoid installing more upstream capacity.
I have tried reading the articles on the PlusNet website about traffic management, but I can't see any indication of what I can expect when streaming the iPlayer.  It does refer to restriction of Content Delivery Networks including those used by the BBC.  If PlusNet is not prepared to support the capabilities of the iPlayer, why does it not make this clear in its advertising?  After all Plusnet is not that much cheaper than its parent company BT which says it does not restrict speed.
7 REPLIES
Twills
Grafter
Posts: 46
Registered: 14-05-2014

Re: Speedtest 17Mbit/s - what iPlayer speed can I expect?

Hi PNRichardC,
Thanks for your time on the phone I'm glad I managed to catch you. As discussed I have reset your line and restored your downstream attenuation to a more stable value. This should prevent what appears to be packet loss causing the buffering you describe. Please give it a couple of hours to complete and keep using the service. I have merged all the open tickets into one (the longest one) incase you need to reply or just update the forum post here.
Hope that sorts things for you
Twills.
PNRichardC
Dabbler
Posts: 14
Registered: 20-10-2014

Re: Speedtest 17Mbit/s - what iPlayer speed can I expect?

Hi Twills
Thanks for your call yesterday, and for the changes to my line.  As far as I can see you increased the Noise Margin from 4dB to 7dB.  As you said it would, the sync speed decreased slightly from 21222kbit/s to about 19000kbit/s, although the speed test went up slightly to 17.2Mbit/s.  This morning I switched off my router and on again to make sure it had reset itself with the changes.  The downstream Noise Margin is now 12dB and the sync speed 16611kbit/s.
Browsing seems slightly faster, although that may be my imagination or luck.
For live television on the iPlayer it still starts at 1470kbit/s then fairly rapidly adjusts to 923kbit/s, then 501kbit/s and sometimes 345kbit/s.
At the weekend a PlusNet customer told me on another forum that he was getting similar data rates on live television, but for catchup items he was able to watch them at 2.8Mbit/s.  When I checked I found I could too.  That is considerable progress, because for a long time the only way I could watch the iPlayer without frustrating interruptions was to download the items.  Curiously the BBC withdrew its streaming speed tester earlier this year.  It is a long time since I used it but if I have remembered correctly it was showing a streaming speed of about 2Mbit/s when a download speed tester was showing 6-8Mbit/s.
I can watch 1080p video on YouTube, but YouTube's buffering is different.
The data rate I am seeing on live television may just be a function of the way the BBC has implemented the iPlayer.  I was curious what other users' experience was, and I am surprise noone else has commented.
Although I have been a PlusNet customer almost since broadband began, I have not previously joined the forum.  PlusNet has always had a good reputation for customer service, but I am very impressed with the speed of response and the quality of the advice and support being given in the forum.
Best wishes
PNRichardC
Twills
Grafter
Posts: 46
Registered: 14-05-2014

Re: Speedtest 17Mbit/s - what iPlayer speed can I expect?

Morning,
You're welcome. The key point really is you can watch 1080p else where. Implying that its the way either the iPlayer is handling its own traffic or how the device is handling flash. From memory although iPlayer uses flash I believe Youtube uses shockwave/flash which will be sending data differently. It's a little weird that live is ok but catchup is not.... Can I recommend the basic steps such as clearing all cache on your browser, trying a different browser, re-installing flash. There is a guide - although I havn't read it - on the iPlayer page regarding buffering common problems. Probably worth checking that out as well.
I did a search for buffering on help and got these topics, hope this helps.
http://iplayerhelp.external.bbc.co.uk/tv/results?nlpq=buffering
Twills.
PNRichardC
Dabbler
Posts: 14
Registered: 20-10-2014

Re: Speedtest 17Mbit/s - what iPlayer speed can I expect?

Hi Twills
Thanks for your reply.  Sorry if I said it the wrong way round but catchup is fine.  I can watch iPlayer catchup at 2.8Mbit/s with no problem.  That in itself is good news because I used not to be able to and had more or less given up trying and as far as possible relied on downloading.
I had not realised there was still a difference between Shockwave and Flash.  I thought Adobe had bought Macromedia about 10 years ago, but I suppose they can still support distinct products.  As a user the difference I see between YouTube and the iPlayer is buffering.  YouTube downloads as fast as it can until it has it has stored the whole clip or programme.  iPlayer only buffers about 1 minute.
Obviously it is more difficult to buffer live television, although the iPlayer seems to run about 1 minute behind the HD satellite feed.  The iPlayer is cleverer than I thought.  It doesn't just reduce speed, it increases it again when conditions improve..  I have not seen it go above 1470kbit/s and it often goes down to 345kbit/s.
What triggered this was trying out another device I had bought.  I found I had to reduce the data rate to 800kbit/s to get something watchable.  The iPlayer seemed the obvious thing to use for comparison to establish what I could achieve on my main computer.
I was also seeing comments that Sky and BT do not carry out traffic shaping or whatever the euphemism is while PlusNet and others do.  In the US I understand Netflix is complaining about Verizon.  It is very frustrating for an end user that there do not appear to be any tools to establish where bottlenecks are occurring.  There is a huge difference between 17Mbit/s from the speed tester and video at 345kbit/s.
I can understand that a high error rate will slow things down.  The error figures reported by my router were not all that high, so again it is puzzling that the figures at the PlusNet end were so much higher.  Anyway the error rate should have improved with the higher noise margin, but it does not seem to have made any difference to the speed I am seeing.
Best wishes
Richard
Community Veteran
Posts: 4,983
Thanks: 376
Fixes: 16
Registered: 10-06-2010

Re: Speedtest 17Mbit/s - what iPlayer speed can I expect?

I think the flash vs shockwave/flash thing was at best poor wording. Youtube and iPlayer both use the same flash browser plugin, but data is sent differently. Youtube typically sends videos over HTTP, iPlayer often uses the RTMP protocol. Youtube videos will of course come from Youtube / Google servers, iPlayer data tends to use the Limelight or Akamai content distribution networks.
PNRichardC
Dabbler
Posts: 14
Registered: 20-10-2014

Re: Speedtest 17Mbit/s - what iPlayer speed can I expect?

I wouldn't expect there to be a huge difference in speed between HTTP and RTMP.  What did concern me is that it says on PlusNet's website that traffic management is applied to Content Delivery Networks and it expressly mentions Akamai, Limelight Networks and Level 3, which it says are used by the BBC, eBay and Facebook, as well as downloads from Apple and Microsoft.
What I can't find anywhere on the website is what effect this is expected to have.  I have seen comments on the MoneySavingExpert forum about throttling by PlusNet.  I have not seen any similar comments on this forum so maybe I am worrying unnecessarily.  It still puzzles me why BBC live television is so slow.
What I was hoping when I started this thread was that other users would tell me what speeds they achieve in terms of content.  Everyone here and on MSE seems more concerned with what the speed tester says.  I can understand that if someone is getting 1Mbit/s because an increase to 2Mbit/s would show a real improvement.  A few days ago on MSE someone was complaining that his speed had fallen from 48Mbit/s to 41Mbit/s and there are other similar comments.  It made me wonder where people were getting their content from to be able to make use of such speeds, or for changes to be noticeable.
Community Veteran
Posts: 4,983
Thanks: 376
Fixes: 16
Registered: 10-06-2010

Re: Speedtest 17Mbit/s - what iPlayer speed can I expect?

Traffic management is applied to all traffic in the sense that all traffic is classified and assigned a priority. You can check the priority using wireshark. Last time I checked, most traffic gets classified as 0x80 (gold).
Using different DNS servers used to result in you getting different IP addresses for content distribution network servers, but more recently other DNS servers got better at directing you to the same plusnet akamai IP addresses that plusnet's own DNS servers would.
If you could determine the IP addresses of the iplayer servers you're accessing, you could run traceroute or pathping to those IPs from a command prompt (although these aren't great, since parts of the route might not respond to the probes, or treat responding to probes as a lower priority than routing the data traffic).