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downstream rate = what speed?

deko747
Dabbler
Posts: 18
Registered: ‎03-08-2007

downstream rate = what speed?

Quick question. if my linksys router (WAG354G V2) says my downstream rate is 6784 Kbps and my upstream rate is 448 Kbps then what speed should i usuallly be getting when i do the +net speed test?
I know the speed isn't a fixed value and it varies with time. but from this it's saying about 6 meg. so should i be expecting about 5 meg out of it?
I've never had more than about 2meg reported from the +net speed tester.
thanks for any help.
16 REPLIES
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: ‎18-07-2007

Re: downstream rate = what speed?

I can see the profile on your account has been set to 4mb since the 28th July, it'll take 3 days of being synced at a higher speed for this to uplift. It's certainly not throttled to 2mb though. If you don't already it'd be worth plugging the router into the master socket and filtering everything else that's plugged in to the line, then run a BT speed test here: http://www.speedtester.bt.com
If you paste the results here, or attach a screenshot, we'll be able to advise further.
deko747
Dabbler
Posts: 18
Registered: ‎03-08-2007

Re: downstream rate = what speed?

OK I'll do this some time later when I've got time and post the results.
But it sounds like provisionally you would agree that i should get more than 2meg or less (as it's reporting today).
in the meantime could it be a setting on my router maybe?Huh
Thanks
deko747
Dabbler
Posts: 18
Registered: ‎03-08-2007

Re: downstream rate = what speed?

OK, I've run the speed tests with the router plugged directly into the main telephone socket.
Here are the results.
plus net speed tester on members page - 2.00 Mbps
plus net My Broadband speed test - 2181 kbps
BT Speed tester resutls -
"IP profile for your line is - 4000 kbps
DSL connection rate: 448 kbps(UP-STREAM)
7680 kbps(DOWN-STREAM)
Actual IP throughput achieved during the test was-3604 kbps"

What does this all this mean ?
(by the way my profile has been set to 4mb since way before 28th july so i'm guessing this is just the last time it was set at that speed?).
Thanks.
deko747
Dabbler
Posts: 18
Registered: ‎03-08-2007

Re: downstream rate = what speed?

Maybe i've just solved my own problem.
While reading a different post on these forums i followed the advice given by the tweak test at http://www.dslreports.com/tweaks. This suggested increasing my RWin setting from 17680 to a value between 76160 and 201280. So I've changed it to 201280 and my reported download speeds by MyBroadbandSpeed and the portal have shot up to 3706kbps.
seems to me that this is more like how it should be.
I've changed the setting back and forth a few times and kept rerunning the tests and it definitely seems to make the difference.
Can I have an expert opinion please cos i've no idea what fiddling with these settings does.
and can someone clarify why this makes a difference - because i've changed this setting on my pc - NOT on my router (which doesn't let me set it). so is this saying i've increased the rcwin for network traffic from router to pc rather than my internet connection?
and why should i have had to change this in the first place?
Community Veteran
Posts: 14,469
Registered: ‎30-07-2007

Re: downstream rate = what speed?

Tweaking the RWIN (and MTU) is necessary because everyone has different equipment / configurations / line conditions (i.e. quality) and MTU/RWIN  is not a one size fits all setting.
RWIN is a PC setting which routers don't have and is the size of the TCP receive window or buffer. The bigger it is the more data that can be received before an acknowledgement to the received data needs to be sent back. However if it is made too big then data one piece of data that is received corrupted will negate the whole buffer which would then have to be sent again in full thus slowing down your throughput. So your line quality and number of errors (and thus retransmits) will be different to someone else so different RWIN values would be needed for both lines.
Also if you tend to access a lot of US bases content then a bigger RWIN may overcome the extra delay in transmissions.
The figure you are using I would say it way too large. You only need a small number of errors in transmission (i.e. the line goes bad for a period of time) to severely slowdown your throughput.
Adjusting MTU can also make a difference but you should always set your router and PC MTU the same to stop packet fragmentation and thus throughput.
Superuser
Superuser
Posts: 9,807
Thanks: 1,183
Fixes: 67
Registered: ‎06-04-2007

Re: downstream rate = what speed?

Increasing RWIN generally does improve speed performance.  The value of 17680 you mentioned is the Windows XP default set by Microsoft.  That value is *not* suitable for ADSL users, it needs to be significantly higher (as you found).  The value affects the efficiency of TCP/IP (network) transmissions between your router and the Internet site your data comes from.
An explanation of RWIN (and MTU) can be found in the portal Help & Support pages under Broadband and Troubleshooting.  In a nutshell increasing RWIN minimises pauses while acknowledgements of receipt are being transmitted.
A value around 120,000 is normally satisfactory but finding one that works best for you is all that is required.  The downside of a larger values is explained in the previous post.
David
deko747
Dabbler
Posts: 18
Registered: ‎03-08-2007

Re: downstream rate = what speed?

brilliant. thanks a lot people.
Community Veteran
Posts: 14,469
Registered: ‎30-07-2007

Re: downstream rate = what speed?

Also remember the RWIN value must be a multiple of MTU - 40 so if your MTU is 1478, the RWIN value must be a multiple of 1438 which is your actual TCP data packet size, the 40 is the IP protocol overhead.
deko747
Dabbler
Posts: 18
Registered: ‎03-08-2007

Re: downstream rate = what speed?

oK. i've reduced my rwin 123,420 and the results from tweak test i think are good. it's given me smiley faces for notes/recommendations and observations. it says i got 99% transfer efficiency, which sounds good to me.
would any one care to comment on these?
http://www.dslreports.com/tweakr/block:39a8722?service=dsl&speed=8000&os=winXP&via=pppoA

and the my broadband speed tester is still reporting 3800kbps.
i think this is a result. Grin
Community Veteran
Posts: 14,469
Registered: ‎30-07-2007

Re: downstream rate = what speed?

Looking at the BT speedtest you posted earlier I think your IP profile is too low @ 4000 for a sync rate of 7680. This should be 7000 which would then improve your throughput speeds.
The IP profile for your line can also be seen on the portal via connection settings -> high speed broadband
It is possible you may have synced lower recently so wait 3 -> 5 days and if it is still 4000 raise a ticket and get it investigated / corrected. That will give you a bigger speed increase than the RWIN tweak.
deko747
Dabbler
Posts: 18
Registered: ‎03-08-2007

Re: downstream rate = what speed?

thanks for the advice. will do.
should i be doing the disconnect - reconnect router thing for the next 5 days to make it resync?
Community Veteran
Posts: 14,469
Registered: ‎30-07-2007

Re: downstream rate = what speed?

Nope.
deko747
Dabbler
Posts: 18
Registered: ‎03-08-2007

Re: downstream rate = what speed?

right, i've got my profile manually set to 6meg, my tweak test report says everything is good and my router is sync'd at
6784.
This is the link to the tweak test results:
http://www.dslreports.com/tweakr/block:12c8b03?service=dsl&speed=6000&os=winXP&via=pppoA
but various speed testers still only give me a max speed of 3.8meg, which is much better than i used to have but it is the speed i achieved from changing my rwin setting. So increasing the speed on my profile appears to have made no difference.
Does anyone else know if there anything else I should be trying?
Superuser
Superuser
Posts: 9,807
Thanks: 1,183
Fixes: 67
Registered: ‎06-04-2007

Re: downstream rate = what speed?

The Tweak-test results are fine.
I suggest rerunning the BT Speedtester to check what IP Profile the BTw DLM system has set for you.  That should be 5500kbps for the sync speed you mentioned.  Please post the result back here.
David