Perfect line stats - but not perfect throughput

Over the past 9 months my download speeds have been around 4.5 to 5.4 Mb/s except for busy periods when it can drop to about 3.

I've tweaked my MTU and used DrTCP to manage RWIN settings.

These are the speedtest results just obtained from BT

"Test1 comprises of Best Effort Test: -provides background information.
IP profile for your line is - 7150 kbps
DSL connection rate: 448 kbps(UP-STREAM) 8128 kbps(DOWN-STREAM)
Actual IP throughput achieved during the test was - 5662 kbps"

My router reports attenuation figures of 4.0db down and 2.5 up, S/N margin is 12 down and 21 up.It hasn't dropped the line in 480 hours online.

I would have thought with these stats I should see spikes where my downloads come close to the maximum possible? I'm online all hours of the day and night, so you'd think in 9 months I'd have been lucky to hit a quiet time.

Funnily enough, using the speed checker on my ISP website I've had the exact same figure (5.44Mb/s) 4 times within 10 tests over a 2 week period - quite a coincidence. Makes me wonder if something is limiting my download speed.

My ISP state they do not impose any restictions on download speeds.

Any thoughts? It would be nice to get the most out of my connection.

Regards,

steve

Any thoughts?

Yes.
ISP and/or BT congestion/contention.
Possibly MTU & RWIN (but as you've tried that...unlikely).

Of course, you're only around 1000kbps off the actual maximum, but with a line like your's I'd be totally peed off if it couldn't go flat out.

Which ISP?
Is it the same at all times (what about after midnight)?
Can you get LLU (BE or Bulldog) at your exchange?

Allowing for contention and congestion I'd still expect a few blistering downloads in 9 months?

My ISP is Madasafish. They don't have any traffic management / shaping as you pay for a monthly allowance, rather than 'unlimited' bandwidth with strings.

Be are coming to my exchange in a few months - I might consider them, they seem to offer a good service.

steve

In reply to:

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Any thoughts?

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Yeah give me your line!!! Count your blessings......it could be worse!!

My office line (Max Premium) with similar stats will peak at 6600 or higher, in fact my home line with a 6500 profile just speedtested at 5473 despite me forgetting to turn off streaming of Terry Wogan.

You didn't say what RWIN and MTU values you settled on.

The exchange links and the ISP both have contention, do other Madasafish users seee peak speeds ?

yeah definetely go with Be, with your line stats you should have no problem getting the full 24meg and a error free line. I'm so jealous you have been blessed with a great line...and bad luck lol j/k

which part of the exchange do you live in