What is Sky's ADSL2 LLU bufferbloat like?

Hi,

Visited my parents recently (who are with TalkTalk) and discovered their internet is suffering from truly horrendous bufferbloat, ie. excessive latency under load. I ran a (few) tests using dslreports speedtest which reports latency under load, this revealed average download latency under load of 1.3 seconds!

http://www.dslreports.com/speedtest/31367189

Does anyone know what Sky's ADSL LLU bufferbloat, especially on low capacity lines (2Mbit) is like?

Thanks,

Kevin

And this sites speed test also reports buffer bloat too https://www.thinkbroadband.com/speedtest

If you use a OpenWrt/LEDE router, you can use SQM to reduce upload bufferbloat, download bufferbloat can also be managed indirectly to some extent for tcp connections. Assuming the ISP network isn't congested, you would be less affected by ISP bufferbloat if you can manage the traffic on your end.

Is buffer bloat an ISP issue?

Usually a function of the buffer/queuing of packets in the router they supply

It's definitely an ISP issue in the downstream side (from them to you), it may be their issue in the upstream if they supplied the CPE router.

The ISP are solely resposible for sizing the buffer in the 'exchange equipment' i.e. the downstream. Trying to control their bufferbloat if they've sized it incorrectly from the wrong end (ie your) of the link is difficult and will always be less than ideal.

In my parent's case, TalkTalk have size the buffer for about 100mS delay on a 24Mbit downstream link. Sadly my parents only get 2mbit so the downstream is overbufferred and we typically see whole second type latencies as the buffer slowly drains across the link. The latency makes the link feel truly awful in the single user case, and as unusable for more than one user. One person browsing today's web pages overfills the link nicely, 2nd person just trying to do a dns looking waits...and waits.

Having a sensible discussion with talktalk is even more challenging.

It's extremely unlikely Talktalk are having issues supplying your 2Mb ADSL line.

What you describe is nothing to do with the ISP at all, but your upstream being completely saturated hugely impacting latency.

Try setting up QoS if your kit has such settings.

http://netalyzr.icsi.berkeley.edu
https://www.bufferbloat.net/projects/bloat/wiki/Test...

I get the exact same on my 45Mb FTTC. If I'm uploading at full speed the downstream will drop considerably and latency increases from 16ms to +100ms.

Edited by j0hn83 (Sun 12-Aug-18 15:41:57)

In reply to a post by j0hn83:

It's extremely unlikely Talktalk are having issues supplying your 2Mb ADSL line.

What you describe is nothing to do with the ISP at all, but your upstream being completely saturated hugely impacting latency.

Try setting up QoS if your kit has such settings.

http://netalyzr.icsi.berkeley.edu
https://www.bufferbloat.net/projects/bloat/wiki/Test...

I get the exact same on my 45Mb FTTC. If I'm uploading at full speed the downstream will drop considerably and latency increases from 16ms to +100ms.

I have measurements. The upstream bufferbloat is actually well controlled despite the fact it's ISP's kit. The download bufferbloat (to be clear, the data FROM the ISP to me) is excessively high, around 1.2 seconds. I can improve the upstream bufferbloat further by using a smart shaper. The downstream bufferbloat is a challenge to control because my control point is at the wrong end of the link.

Your FTTC sounds bufferbloated in the (traditional) upstream direction. You would almost certainly benefit from the shaping & fairness of the CAKE shaper.

http://www.dslreports.com/speedtest/37724657

ran a test dunno if that helps any.

In reply to a post by epyon:

http://www.dslreports.com/speedtest/37724657

ran a test dunno if that helps any.

Yes, very helpful. And a good result as well. Thank you