Got 1MB broadband and am uploading files to a webserver at a steady slow 30 kbs (US located server). How come this sklow upload speed has also reduced my downloads to a crawl as well. I am downloading at a stupid 56k modem speed while this upload is running.......what is going on here....if I PAUSe the upload, normal download speed resumes, what could this mean?

Originally posted by goldenfleece
Got 1MB broadband and am uploading files to a webserver at a steady slow 30 kbs (US located server). How come this sklow upload speed has also reduced my downloads to a crawl as well. I am downloading at a stupid 56k modem speed while this upload is running.......what is going on here....if I PAUSe the upload, normal download speed resumes, what could this mean?

Thats why its called "Asynchronus Digital Subscriber Line" - you dont get the same upload speed as download speed. Of course if you are uploading AND downloading at the same time it will slow down!

But my bandwidth normal download speed measures 900 kbs when not uploading, so how come uploading at a mere 30 kbs I get a download speed reduced to less than 100 kbs? What has happened to the other 800 kbs bandwidth? Where does it go?

Originally posted by goldenfleece
But my bandwidth normal download speed measures 900 kbs when not uploading, so how come uploading at a mere 30 kbs I get a download speed reduced to less than 100 kbs? What has happened to the other 800 kbs bandwidth? Where does it go?

Check with your ISP on your contention ratio. It could be that you have to share the bandwidth with other users. This would esily explain the slow speed. Also dont try uploading and downloading at the same time.

Either that or the Pixies stole the bandwidth?

Originally posted by Avalon
Check with your ISP on your contention ratio. It could be that you have to share the bandwidth with other users. This would esily explain the slow speed. Also dont try uploading and downloading at the same time.

Either that or the Pixies stole the bandwidth?

your not really sure what you're talking about are you.

Uploading should not affect your download speed GF, give your ISP a call and get them to check it out.

Originally posted by Cyclone
your not really sure what you're talking about are you.

Uploading should not affect your download speed GF, give your ISP a call and get them to check it out.

actually uploading at full speed WILL affect your download speeds, but not for the reasons avalon is babbling about...

when your downloading you have to send request and ack packets, when your download speed is significantly larger than your upload this can have major impacts on download speed when uploading with limiting...

generally on an ADSL 1024/256 line you need to set your max upload speed in software to about 25kb/s to leave 5 - 10kb/s "headroom" for downloading at full speed...

Are you reading and writing from the same physical drive?

If it's a slow drive, that might have an impact.

Joe

Originally posted by Cyclone
your not really sure what you're talking about are you.

Uploading should not affect your download speed GF, give your ISP a call and get them to check it out.

I do work for an ISP! I should know what im talking about been as ive been doing it for nealry 3 years.

Have a look at this page, and tell me that using ADSL and uploading and downloading at the same time cannot affect your download speed: http://www.webopedia.com/TERM/A/ADSL.html and then look at this page which will expalin the theory of bandwidth to you: http://www.webopedia.com/TERM/B/bandwidth.html

Basically your bandwidth is a pipe. If you are sending traffic up and down the pipe at the same time, then the traffic will hit each other more often, thus resulting in packet loss, thus forcing a re-send of the lost packets, and thus slowing down both your upload and download speed.

So yeah, basically i DO know what im talking about.

Originally posted by xafier
actually uploading at full speed WILL affect your download speeds, but not for the reasons avalon is babbling about...

when your downloading you have to send request and ack packets, when your download speed is significantly larger than your upload this can have major impacts on download speed when uploading with limiting...

generally on an ADSL 1024/256 line you need to set your max upload speed in software to about 25kb/s to leave 5 - 10kb/s "headroom" for downloading at full speed...

good point, hadn't thought of that.
What are the actuall ratios of data sent back in ack's to data coming down? Presumably the acks are a lot smaller than the incoming data packets.

JP - that would have to be a seriously slow drive, most drives these days are measured in 100 MBytes/s whereas broadband is measured in 1's of Mbits/s.

Originally posted by Cyclone
your not really sure what you're talking about are you.

Uploading should not affect your download speed GF, give your ISP a call and get them to check it out.

Oh and contention IS another factor. Its 50:1 with BT, so at any one time you are sharing your bandwidth from the exchange with up to 49 other users.

It would need to be a slow drive, or a seriously fragmented one.

Just worth checking all bases!

:)

Originally posted by Avalon
I do work for an ISP! I should know what im talking about been as ive been doing it for nealry 3 years.

Have a look at this page, and tell me that using ADSL and uploading and downloading at the same time cannot affect your download speed: http://www.webopedia.com/TERM/A/ADSL.html and then look at this page which will expalin the theory of bandwidth to you: http://www.webopedia.com/TERM/B/bandwidth.html

Basically your bandwidth is a pipe. If you are sending traffic up and down the pipe at the same time, then the traffic will hit each other more often, thus resulting in packet loss, thus forcing a re-send of the lost packets, and thus slowing down both your upload and download speed.

So yeah, basically i DO know what im talking about.

Funnily enough I already understand both ADSL and bandwidth.

And yes, the overall bandwidth is shared between the two (it's ADSL because the ISP restricts the upload speed more than download speed).

This is obviously not what is happening in this case though, as 900Kb downstream does not equate to 30Kb up and 30Kb down. unless some bandwidth gremlins are on the loose and eating it.

Maybe you should go back and learn some basic physics, packets of data as sent over copper wire do not 'hit each other'. Packet collisions (what you're talking about) occur when two devices try to send a packet at the same time, and when this happens both back-off and try again later, which has the effect of slowing down your connection. This effect doesn't explain why the downstream bandwidth is being so severly restricted when uploading though.

Originally posted by Avalon
Oh and contention IS another factor. Its 50:1 with BT, so at any one time you are sharing your bandwidth from the exchange with up to 49 other users.

contention ratios would explain a general lack of performance (particularly when all the users were online at the same time).
It doesn't explain the reduction in downstream bandwidth when uploading.

well to be honest 900Kb/s doesnt equate to a 1Mbit connection either... I don't even get those speeds on my 5.5Mbit Bulldog connection...

At the end of the day if he wants to solve his problem he just needs to go into his FTP program and set its max upload speed... if he set it at about 25Kbytes per sec his downloads will be fine :)

[edit]

thats assuming his upload is 256Kbit like most non-LLU lines are

Originally posted by xafier
actually uploading at full speed WILL affect your download speeds, but not for the reasons avalon is babbling about...

when your downloading you have to send request and ack packets, when your download speed is significantly larger than your upload this can have major impacts on download speed when uploading with limiting...

generally on an ADSL 1024/256 line you need to set your max upload speed in software to about 25kb/s to leave 5 - 10kb/s "headroom" for downloading at full speed...

Can't find the figures but this is the correct answer. If you are uploading it can really hit your d/l speed due to there been no bandwidth left to send the Requests and Acknowledgements required for incoming traffic.

.... another possible cause for reduction in speed can be the performance of the server at the other end.

http://homepage.ntlworld.com/robin.d.h.walker/cmtips/downup.html says what some of the others have been saying really.

I suffered this problem a lot using NTL cable service but I haven't noticed it really since using DSL.

If you go to http://www.dslreports.com they have a tool that analyses your connection and settings and makes suggestions for changes you could make.

Originally posted by xafier
actually uploading at full speed WILL affect your download speeds, but not for the reasons avalon is babbling about...

when your downloading you have to send request and ack packets, when your download speed is significantly larger than your upload this can have major impacts on download speed when uploading with limiting...

generally on an ADSL 1024/256 line you need to set your max upload speed in software to about 25kb/s to leave 5 - 10kb/s "headroom" for downloading at full speed...

Yup, if there's no ACK packets then the server will stop sending it - doesn't matter what hard drive you have, what state it's in or what the other server is up to - if you are uploading at full whack then downloads will be reduced to a similar figure as the ACK packets have to queue up instead of being sent immediately. It's a drawback in the way TCP works.

Small note, you can increase performance a little bit by changing your MTU settings to the highest packet size you can without fragmentation...

usually about 1434 I think with most ADSL providers... and there are a few other options in networking to change too that will allow download packets to be larger and decrease the number of requests and acknowledgements :)

if I was at home I'd provide some links, but I dont have them on me at work... try and search for stuff to do with optimizing internet connections :)

Originally posted by fnkysknky
Yup, if there's no ACK packets then the server will stop sending it - doesn't matter what hard drive you have, what state it's in or what the other server is up to - if you are uploading at full whack then downloads will be reduced to a similar figure as the ACK packets have to queue up instead of being sent immediately. It's a drawback in the way TCP works.

unless you can prioritise your traffic so that acks jump to the front of the queue. At a guess windoze cannot do this.

Download netlimiter, top program, might help.

Download netlimiter, top program, might help. :)

Originally posted by Avalon
I do work for an ISP! I should know what im talking about been as ive been doing it for nealry 3 years.

Have a look at this page, and tell me that using ADSL and uploading and downloading at the same time cannot affect your download speed: http://www.webopedia.com/TERM/A/ADSL.html and then look at this page which will expalin the theory of bandwidth to you: http://www.webopedia.com/TERM/B/bandwidth.html

Basically your bandwidth is a pipe. If you are sending traffic up and down the pipe at the same time, then the traffic will hit each other more often, thus resulting in packet loss, thus forcing a re-send of the lost packets, and thus slowing down both your upload and download speed.

So yeah, basically i DO know what im talking about.

Dont mean to be funny, but thats complete arse.

Cyclone and others are right, its because you upload is being swamped with the data you are sending out, so ACK packets, and other GET type information is taking longer to send.

ADSL Does mean Asymmetrical Digital Subscriber Line, but only in the sence that the up is less than the download. It happens on SDSL as well if you max out your upload. Unless you have a burstable line, which is highly unlikely on any form of Copper DSL.

Joel

The real solution to the problem is QoS (Quality of Service) I have it setup on my openBSD box that acts as our firewall. Set to that web, ACK, and email traffic are routed at first prioraty, and downloads routed at a lower level, which is kind of how net limiter works, in a round about way.

Joel

I'll add my recommendation for Net Limiter too. Stops all your applications fighting over bandwidth, great when you are doing multiple things at once. As the name implies it limits each applications bandwidth up and down.