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I am using Virtual PC 2007 on Windows Vista Enterprise x86. My confusion is about the network setting for guest OS. In the network setting, I can set the network adaptor of guest OS to one of my physical network adaptors of my host OS (I have tested that it works for guest OS to use the physical network adaptor of host OS to access external network).

But in this way, 1. since both host OS and guest OS will use the same physical network adaptor, will there be any conflicts (e.g. same H/W serves two OS)? 2. will guest OS share a part of network bandwidth of the host OS of the physical network adaptor? 3. What means NAT setting in guest OS network connection adaptor?

thanks in advance, George

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  1. No, there won't be any conflicts. The way Virtual PC networking works, VPC driver will simply inject and listen for packets, a little like Wireshark's WinPcap.

  2. Yes, the bandwidth will be shared.

  3. NAT is used when you don't want to attach to any network interface; it attaches to VirtualPC internal router. (This only allows outgoing connections.)

If you want the virtual machine to look like a real one, both from inside and outside, then attach to a physical interface. The VM will be accessible from all other boxen in that network - just like a real one. You can use file sharing, etc.

If you just want to be able to make outgoing connections from the VM, then NAT is enough.

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From end user point of view, what is the differences between NAT and select to use one of the physical network adaptor? As you said both of them can access external network, I am interested to know in which scenario we should select NAT and in which scenario we should select to use one of the physical network adaptor. – George2 Jun 3 '09 at 15:42
Answer updated. – grawity Jun 3 '09 at 15:45
1. Could I understand in this way, when using NAT, I could only access from guest VM OS to outside network resource, but can not access from external network to guest VM OS? 2. When using NAT, what is the IP address of guest OS? – George2 Jun 3 '09 at 16:06

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