Strange bandwidth limiting

stephenw10

Hi All,
I hope someone can point me in the right direction here because at the moment I can't think what the cause of this could be.
I just spent a number of days talking with my ISP trying to trouble shoot a downstream bandwidth throttling I am experiencing. After trying everything we could think of, and increasing my connection speed in the process, I eventually went back to basics and connected a single pc directly, no throttling. Should have tried that first! ::)

Anyway the symptoms are that I can max out my downstream bandwidth only by simultaneously downloading several files. Each file seems to be restricted to ~8Mb/s. With three files I can achieve around 20Mb/s which is the most my dsl will support. Connected directly to my dsl modem (Draytek Vigor 120) using the windows PPPoE client I can download any one of the three files at 19Mb/s. It's almost as if I have somehow turned on traffic shaping without realising.

I am running 1.2.3 NanoBSD install on my old Watchguard Firebox. I previously experimented with load balancing but have now removed the pools. I have the vhosts package installed but do not use it.

Any suggestions much appreciated.

Steve

![plusnet download test 3.jpg](/public/imported_attachments/1/plusnet download test 3.jpg)
![plusnet download test 3.jpg_thumb](/public/imported_attachments/1/plusnet download test 3.jpg_thumb)

stephenw10

Forget that!

Testing with a different PC shows no restriction.

Also running:

fetch -o /dev/null http://download.thinkbroadband.com/512MB.zip

Showed no restriction at the pfSense box.

Steve

stephenw10

Booting the same machine from an Ubuntu USB stick also showed no restriction so I investigated further.
It turned out to be the tcp receive window incorrectly set in Windows XP. It's supposed to have auto scaling but it didn't seem to be working, setting a few registry keys solved it. See:
http://www.psc.edu/networking/projects/tcptune/OStune/winxp/winxp_stepbystep.html

Steve