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Im running Virtualbox on a Ubuntu 12.04 server (host) and I'm running a Windows 7 as guest os. Im using the (virtual) Intel PRO/1000 MT network card.

I get good network performance for download using both nat and bridged network settings but upload speed is really slow using nat.

I have tied this on tow different servers, one brand new, and one a several years old, both gave the same result.

If you can explain this behavior or have ideas of further test I can perform please let me know.

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2 Answers 2

up vote 5 down vote accepted

I used the following setting:

modifyvm <vm> --natsettings1 1500,1024,1024,1024,1024

This is what I came up with based on http://www.virtualbox.org/manual/ch09.html#nat-adv-settings

--natnatsettings<1-N> [<mtu>],[<socksnd>],[<sockrcv>],[<tcpsnd>], [<tcprcv>]

It looks like a dev made a units conversion issue with the send speed vs download speed. By default the "tcprcv" is way way way higher than the "tcpsnd".


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Thanks! This really made my day. I got a great result by using low buffering and maximum send and receive windows. –  user1622094 Nov 21 '12 at 12:56
I'm struggling with the same problem, and I've tried a variety of values in in the --netsettings options with no change. I'd be interested to know which precise values worked for you. Can you please share? –  Avian00 Mar 7 '13 at 16:07

On Ubuntu 14.04, I had to use the virtio NIC type to get decent speeds from VirtualBox:

modifyvm --nictype1 virtio
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