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Wifi ftp-http download issue

Last response: in Networking
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December 13, 2012 3:41:26 PM

Hi There,

I own a Toshiba laptop and I have a 15Mbit home connection (DSL) which I use via WIFI (150mbit N wireless TPLink router I have)
Lately my ftp and http download speeds got "capped" at 420kb/sec max which is roughly 3Mbit instead of the 15Mbit I have.
No matter what ftp, website I try the speed is never faster than 420-440kb/sec WHILE if I run a torrent I can max up my 15Mbit at 1850kb/sec

I have tried other wifi networks to rule out the wifi adapter error and it is the same issue.

Seems like my FTP and HTTP downloads are capped no matter what.

What do you guys think? Is this a windows xp problem, or how could I fix this?
Really annoying that I can only get the good, full speeds if I download via TORRENT, when I go FTP or HTTP download the speed is maxed at this ridicolous 420-430kb/sec.

HEEEELP :o 
December 13, 2012 9:56:01 PM

It is a fundamental issue with how TCP works. A single TCP stream can only have so many packets outstanding that are not acknowledged. It must wait until these are acknowledged as having been received before it can send more. The main problem comes because it takes time for these messages to travel. Say I can send 32kbytes of data until I have to wait. On a 15m link it will take 16ms to transmit it. Now if I have to wait another 100ms to get the answer I am actually only transmitting 32k bytes every 116ms which is about 2m/sec not 15m. And this would be under perfect conditions.

This problem is related to TCP window size. There are some minor things that have been done to correct it but it can't really be fixed.

The reason torrent is higher is you have many tcp session each with their buffer and wait. Because you can run them all at the same time you can use more total bandwidth.

December 14, 2012 8:32:03 AM

john-b691 said:
It is a fundamental issue with how TCP works. A single TCP stream can only have so many packets outstanding that are not acknowledged. It must wait until these are acknowledged as having been received before it can send more. The main problem comes because it takes time for these messages to travel. Say I can send 32kbytes of data until I have to wait. On a 15m link it will take 16ms to transmit it. Now if I have to wait another 100ms to get the answer I am actually only transmitting 32k bytes every 116ms which is about 2m/sec not 15m. And this would be under perfect conditions.

This problem is related to TCP window size. There are some minor things that have been done to correct it but it can't really be fixed.

The reason torrent is higher is you have many tcp session each with their buffer and wait. Because you can run them all at the same time you can use more total bandwidth.

I see, but how do I fix this ?
This problem is completely new, it started a few days ago only. and now it is constant.
Can I fix the TCP windows size with some patch or something ? This is truly annoying and I do not want to re-install my whole system. (XP Professional)
Please let me know how I could fix this. The other machine (ACER netbook) can download using up the FULL 15mbit bandwith of our DSL. only this Toshiba laptop is acting up with FTP and HTTP downloads. :( 

HEEEEEEEEEEEEELP :pt1cable: 
!