virtualbox.org

Dear all,

I am trying to run three Debian guests, all with bridged network connections. I have tried this both on a Windows host with Oracle VM VirtualBox 4.1.6 and on a Debian host with Oracle VM VirtualBox 4.0.14. Same error happens on both setups.

Starting the first guest works fine, but as soon as I start the second guest, I loose the network on the host. "Network cable unplugged" is the message I get when running on the Windows host.
If I leave the machines running for some time, the network on the host is recovered. Running

ifconfig

on the guests tells me that they seem to have gained an okay network. But, as soon as I do something on a guest that requires network traffic, the host network adapter reports "network cable unplugged" again, and network is once again lost for a while.

What am I doing wrong? Is there some limit set for the network adapter on the host that prevents me from running more than one bridged connection at a time?

System information:
Host computer: HP Workstation Z400.
Host OS: Windows 7 Professional (64 bit).
Oracle VM VirtualBox 4.1.6.
Guest OS: Debian 6 (squeeze), updated today.
Physical network adapter on the host: Broadcom NetXtreme Gigabit Etherenet.
In the VirtualBox network settings for the guest, I have tried different adapter types and different types of promiscuous mode, without success.

How were the guests created? By doing one install and then cloning? If so, did you remember to change clone's MAC address and machine names etc so that they can coexist on the same network?

Are you on a home LAN or a company LAN?
Many companies limit their LAN ports to only one MAC address. In this case you would need to use NAT networking to share the single MAC address of the host.