NDLAN - The Langton Green BT exchange broadband performance

[RobL]

Wow

Must be the effect of the London Marathon. I'm getting 910 KB/s download from Oracle today over my Zen Internet ADSL Max connection. That's close to the maximum theoretical performance, with NO contention. Everyone else must be out in the garden, in the sun. Just me at home downloading Oracle ISOs.

--RobL.

[RobL]

Ah ha ... too good to be true. Dropped to 600 KB/s now ... someone must be sharing the bandwidth with me now. Ah well. It was nice while it lasted.

[stonewall100]

Mine showed a pretty stable 6.7-6.9 yesterday, apart from a drop to 5.2 at 15.00 - so it sounds as if Zen needs to get its act together.

Lawrence

[Paul W]

stonewall100

Mine also stable between 6.7/6.9Mbps download via BT. Have experienced some "contention" around 14 to 16th April but seems to have flat-lined now around the higher figures. Surely Rob's 910 to 600 Kbps via Zen can't be right???

Paul W

[RobL]

Ah ha ... too good to be true. Dropped to 600 KB/s now ... someone must be sharing the bandwidth with me now. Ah well. It was nice while it lasted.

Lawrence ...

What factual basis do you have for your statement about Zen? Please be careful not to play the game the big ISPs do.

There are many factors that could explain why my ADSL Max line did what it did, while both you and Paul experience good performance. We can start with different line cards, then localised load on the DSLAM and ATM router all of which happens before the ATM virtual circuit is used to tunnel the traffic back to Zen through the RAS service and Collossus cloud.

http://www.kitz.co.uk/adsl/equip2.htm

That link is a bit dated (contention ratios aren't used anymore), but it gives you an idea of what's involved. Of course, the ISPs don't provide us with any backhaul infrastructure detail, as it is commercially to their advantage not to do this - FUD.

The one strong factor we have is the aggregated performance of our population of whiteboxes. This is evidence that can't be ignored by any ISP using BT OpenReach's ADSL infrastructure across the parish. Every single one of them is a valid data point, with the sheer number ruling out "anomalies" often used to dispel a persistent customer from pursuing their ISP further.

--RobL.

[Milo O'Shea]

I'm wondering something similar: SamKnows trumpets our respectable average figures, but we still have occasional extreme lows eg 0.59Mbps at 1900h on Friday 4 May. However, I have noticed that in recent weeks we have been able to download programmes from BBC iPlayer remarkably quickly, whereas a few months ago we abandoned streaming programmes, performance was so poor and switched entirely to downloads, which are useless for ITV & C4. Not sure whether this improvement is merely due to lower usage by contending neighbours or whether the system has actually improved.

Milo

[RobL]

I'm wondering something similar: SamKnows trumpets our respectable average figures, but we still have occasional extreme lows eg 0.59Mbps at 1900h on Friday 4 May. However, I have noticed that in recent weeks we have been able to download programmes from BBC iPlayer remarkably quickly, whereas a few months ago we abandoned streaming programmes, performance was so poor and switched entirely to downloads, which are useless for ITV & C4. Not sure whether this improvement is merely due to lower usage by contending neighbours or whether the system has actually improved.

Milo

Hi Milo - my guess, and it has to be a guess, is the backhaul bandwidth from our NDLAN exchange is in the process of being upgraded by BT in preparation for the likely ADSL2+ upgrade. This would benefit current subscribers using the ADSL Max (8 Mbps) services as contention would be reduced. There is ALWAYS an upper limit, which you may have experienced on Friday 4th at 19:00.

07-06-2012 09-53-51.jpg

I've attached above the Sam Knows graph for May 4th in Speldhurst, that you can see the problem was most likely localised to you in some way. Although trending downwards in the early evening, the average download speed across the 60 whiteboxes we have at the moment says 3.7 Mbps was the average on May 4th at 19:00. It could be the "line card" that you and your neighbours are on is particularly busy, and we don't have the statistical data to report accurately the localised effects of that congestion.

It's your call to decide whether this is worth reporting to your ISP. It is below the acceptable threshold for BT OpenReach's ADSL Max product if you get reasonable speeds other times of the day, however it is only during "peak" times which may be allowable according to your agreement with your ISP.

--RobL.