slow TCP transmisson in one direction?

[zubziro]

Hi

I'm having troubles with Vista'x64 -> Linux -> GB Lan transmission.


When i test connection (with "iperf" on both sides) from Linux to Windows i get 633 Mbits/sec.
But then i run another way around from Windows to Linux i only get 357 Mbits/sec!


I' have tested connection from my third computer Mac to Linux and it is around 650 Mbits/sec.
So the problem must be on Windows side.

Another test from Linux to Mac shows transfer 635 Mbits/sec!
From Windows to Mac = 200 Mbits/sec.

So as you see every output connection from Windows is very slow. :-(



(Input Windows)
Mac->Ws = 950
Lin->WS = 633

(Output windows)
WS->Lin = 357
WS->Mac = 200

(Others)
Mac->Lin = 650
Lin->Mac = 635


There is one setting in "iperf" that makes it different:
when I set TCP Window size to 56KB i get transfer of: WS->Lin = 702 Mbits/sec.


As I understand setting of TCP Window size is gone in Vista, replaced by "Vista TCP Window Scaling Auto Tuning" so



is there something I can do to improve permormance ?


Thanks!

p.s. I know there isn't much info in this post, but if I put everything thecnical about situation it would probably take a lot of place.
Ask me instead of thing that could be intresting.

 

[burtsbees]

So the problem must be on Windows side. "

duh...lol

You can try DRTCP (free download)...

what about fragmentation?

/

 

[zubziro]

Thank for answer!

As I understand DRTCP wont help on Vista isn't it for win200/XP ?

Cay you tell more specific about fragmantation do you think it is a switch/router issue ?

(I dont know much about fragmentation is it related to MTU)

my router is dir-655 I think there is no MTU settings there but it supports 9k MTU.

Linux shows 1500 MTU and windows is 1514

Thanks.

 

[burtsbees]

That 1514 is extra overhead, and default MTU is 1500. That could be some sort of RIP listener or vlan bull$h1P in Vista. That is likely the problem. Increasing MTU may solve it.

DrTCP may work in Shipsta, and you can tweak MTU in drtcp...

/