virtualbox.org

Hi all,

I am using Ubuntu 9.04 host, VirtualBox 2.1.4, and Windows XP SP3 as guest. I have set up an iperf server somewhere on my network. Using the Ubuntu host, I can get a bandwidth of about 94 MB/s, but when I use the Windows XP guest, I only get maximum 30 MB/s.

I use the Intel PRO/1000 T server NIC, and host interface under virtualbox. I am running out of options here. Is there any way to improve the bandwidth of the guest OS?

For additional information, I also have a Xubuntu 9.04 guest under the same Ubuntu host. When I do iperf from the Xubuntu guest, I get the bandwidth very close to that of the host, around 93 MB/s.

Any comments are appreciated...

You may want to edit the Windows network adapter and set the MTU at 1500.
Also Windows tries to set things up slower than others and adjusting the CTS/RTS helps a lot.
All of these are registry changes in XP but there are programs out there that will tune this for you.
Type improve windows xp network performance in google and see what you can find

Perryg wrote:You may want to edit the Windows network adapter and set the MTU at 1500.

Sorry, but Windows won't set an MTU smaller than 1500 by itself, will it?

skoehler wrote:

Perryg wrote:You may want to edit the Windows network adapter and set the MTU at 1500.

Sorry, but Windows won't set an MTU smaller than 1500 by itself, will it?

Maybe, but what if it's semi-forced in the driver? Then Windows will adhere to it and set the MTU lower, to say 1480 instead of 1500.

Thank you for your replies, guys.

First of all, I need to clarify a few things. I'm using VirtualBox to run custom applications developed under Delphi to run under Windows. The applications run under Ubuntu host with Windows XP guest VirtualBox 2.1.4. But the applications got disconnected a lot. At first, I thought the problem was due to low bandwidth. Then I tried to find ways to increase the bandwidth, hence the first post of this thread.

Then after doing lots of research, one of them like suggested by Perryg, I did get an increase in bandwidth. But the increase didn't solve my problem. I then tried to run Windows Server 2003 under VirtualBox which after TCP optimization, got me close to 60 Mbps, which is actually very close to native Windows XP bandwidth (70 Mbps). But the problem persists.

Then I tried something else, I connected the Ubuntu host, hosting a Windows XP guest to a 10 Mbps hub. The bandwidth dropped to 8 Mbps. Surprisingly the connection of the applications under Windows XP was very stable. So the problem was not of the bandwidth afterall.

I then upgraded VB from 2.1.4 to 3.0.2... The problem persists. Lots of disconnects on 100 Mbps network. After googling around... I found out that 3.0.2 has a few bugs on the networking departmen. I then downgraded to 2.2.4... the problems are gone. I get around 68 Mbps under Windows XP guest, Ubuntu host, VirtualBox 2.2.4. And the connection is very stable. No disconnection at all...

Problem solved!

You should post a ticket with bugtracker. Post a link to this page to keep you from having to fill it all out again and let the Devs see what is going on.
You will need to setup an account there because it is on a different system. The link is below my post.