Predicted and real speeds

I've just had FTTC installed by Zen. Predicted speeds (from Zen) on an 80/20 contract were 59 Mbps download and 18 Mbps upload. My line is syncing at 78104. What I actually get is between 40 and 46 Mbps download and around 7 Mbps upload. Zen support staff have established that everything seems to be in order and say that since what I'm getting is well above threshold levels there is nothing that can be done. My question: What is the value of the prediction on the basis of which you place your order if you then actually get nothing like it in reality? (Especially when you're then tied in to an expensive ISP for a minimum contract period.)
I've had ADSL from Zen for a number of years and have been well pleased with them as an ISP till now -- and the actual speeds I got of 17/1 tied in exactly with the prediction for my line.

I wonder whether my experience is relevant?

When I had fibre installed I checked the speed and got all sorts of results from various speed checkers well below the predicted values, with thinkbroadband's checker being the worst. I eventually realised that the cause was checking using wireless, with the wireless connection being slower than the line speed. Using a cable instead gave me consistent speed results close to the predicted value.

Can you PM me your details please so I can take a look. When you do, can you let me know if you are using wireless or if you are using ethernet.

Kindest Regards,

I don't have much faith in the various download testers and suspect that a lot of sites cannot keep up with 'superfast' broadband. Some ASDL modem/routers, when operating with the BT Openreach modem may not be fast enough for high speed FTTC connections. Are you using your own or the Zen supplied one? I'm using a Billion 7800n which I originally bought because we had quite a long copper line to the exchange.

The fact that your line is syncing at 78Mb means you should be getting about 74Mb if there's no bottleneck.

What measurement gives you the 40-46/7Mb figures that you report?

My Zen FTTC circuit syncs at 93/33Mb so II should have the full '80/20' experience which, due to overheads is more like 76/18.

I have a broadband monitoring box from www.samknows.com and it records my measured speeds as 74/17 which is pretty close to the maximum I could ever expect. The traffic is only measured between the Samknows box I have across the Zen network and into the Sam Knows' ISP and network. I'd expect this link to be quite short and fast.

A Think broad band test (flash based) just now reported 64/13 and the BBC iplayer diagnostics came in at 69Mb. A speedtest.net test reports 70/16Mb so there is some discrepancy across testers.

I'm using the Zen-supplied TG582n router, whichis supposed to be fully capable of dealing with the speeds.

The measurements I reported come from three speed-testers: BT, speedtest.net, and thinkbroadband. Although they vary a little, and of course from time to time, they all come in regularly within the same range. On Zen's advice I checked linking direct to the BT modem, which makes no difference. (I also checked using another machine, to rule out problems with my PC itself.)

The results from testers just before posting this are:
BT 47.06 down, 7.09 up
thinkbroadband (Flash) 38.85 down, 9.09 up
thinkbroadband (Java) 40.8 down, 7 up
speedtest.net 45.41 down, 9.10 up

From from the tests you've got about 45/9 give or take a bit.

Do you know what speed your line in syncing at currently?

If it's still 78Mb then something is not right.

With regard to the predicted speeds I think they're something of an educated guess. BT will probably have data on ADSL lines connected through your cabinet and might have data on how close the cabinet is to your compared to the exchange. Based on that sort of information I suspect they predict the expect speed.

My line was predicted to be 69Mb but currently syncs at 93/33 which is quite a lot more.

It is indeed still 78 Mb, and the actual speeds obtained remain as low as before, so I'm very disappointed indeed with what I'm getting. But Azzaka (see above) from Zen is looking into it for me in much more detail than the support people I spoke to before, for which I'm very grateful - testimony to the value of this forum!

If you're on Windows XP, you may have TCP Window Scaling disabled, which can hold down throughput (we had a case of this recently in another forum here). This is unlikely to be an issue with later versions of Windows.

In reply to a post by rinbad:

It is indeed still 78 Mb, and the actual speeds obtained remain as low as before, so I'm very disappointed indeed with what I'm getting. But Azzaka (see above) from Zen is looking into it for me in much more detail than the support people I spoke to before, for which I'm very grateful - testimony to the value of this forum!

I have a similar problem every two months on IDNet. It's a bit of a stretch to suggest it's the same thing though. In my case it starts on the 19th of every even numbered month and lasts for four days after which rebooting the router cures it. If you ever get a resolution I hope you'll come back and let us know what Zen say I've had no luck getting IDNet to investigate it. They claim it's either congestion or REIN :-/

Still looking into it. It's doesn't appear to be congestion and the PIPE doesn't appear to be stopping it either.

We're still investigating. Bit of an awkard pickle to be honest.

Do you have any issue with lost packets?

Even packet loss of a few percent can slow TCP transfers down a lot.

Try 100 or even 1000 pings to the BBC or a Google server.

Just to confirm that I am having a near identical experience as rinbad... Predicted speeds were 58/18 and reality is 40-45/8 .

However Zen support say that the Openreach modem is syncing at 60/20.

Taking all cabling/routers out of the equation with laptop directly plugged into modem its still 40-45/8.

Did you get a resolution at all?

Thanks

Mark